Herpes Simplex Ebooks Catalog

Stop Herpes Now

You'll discover: What foods are bad for you, encouraging outbreaks. What foods are good for discouraging outbreaks. The connection between genital herpes and stress. What herbs actually suppress the herpes virus. How to heal your body naturally and safely. How to manage stress in your life.

Stop Herpes Now Summary

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Author: Dr. David Hogg
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I usually find books written on this category hard to understand and full of jargon. But the writer was capable of presenting advanced techniques in an extremely easy to understand language.

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Lucke Tumor Herpesvirus

In size and structure, LTHV is similar to herpesviruses found in both higher vertebrates (humans) and lower vertebrates (fish). Virions in infected cell nuclei measure approximately 100 nm in diameter, with the size increasing after cellular membranes are acquired extracellular virus increases to about 170 nm (Fig. 1). AMPHIBIAN HERPESVIRUSES (HEHPCSWRfDAE) 51 The DNA of LTHV is a linear, double-stranded molecule with a base composition of 45 47 guanosine plus cytosine (G + C) and a molecular weight of 66 X 106, as determined by contour length measurement. If this value is confirmed by other methods of measurement, it is much lower than that of other herpesvirus DNAs. Figure 1 (A) Thin section of an inclusion-bearing Lucke tumor cell with typical herpesvirus particles in various stages of development in the nucleus. X19400. (B) Enveloped virions found extracellularly. x24 000. (C) Negatively stained nonenveloped particle showing typical herpesvirus morphology. x 110 000. (Reproduced...

Epigenetic Modifications of Latent yHerpesvirus Genomes

Y-Herpesviruses replicate in epithelial cells (lytic infection) and establish latency in lymphoid cells in vivo. In y-herpesvirus-infected lymphocytes and lymphoblastoid cell lines cultured in vitro, both virus production and tight latency can be observed. Latent y-herpesvirus transcripts frequently encode oncoproteins and protein non-coding small RNAs that may contribute to immortalization and malignant transformation of host cells. Although y-herpesviruses are favorite subjects of epigenetic studies, there are no data yetonthe associationoflatent, episomal y-herpesvirus genomes with different nuclear subcompartments (euchromatin or heterochromatin). Association of EBV genomes with the nuclear matrix (Jankelevich et al. 1992) and a colinear arrangement of the functional units of a 30-kb region the EBV genome with the rearranged human immunoglobulin gene loci (Niller et al. 2004a) suggest, however, that a viral LCR may control latent EBV gene expression in a host cell-dependent manner...

Activator Repressor Complexes and Histone Modifications in Regulatory Regions of yHerpesvirus Genomes

A series of cell type-specific or general transcription factors bind to regulatory regions of y-herpesviruses. Most of them were identified in in vitro experiments. In vivo footprinting studies partly supported and partly extended these results. A consequent finding at the EBNA 2-activated Cp and LMP2Ap of EBV was the presence of a CBF1 footprint(s) in cells actively using these promoters and the absence of a typical CBF1 footprint in cells with silent Cp and LMP2Ap (Salamon et al. 2001,2003). This implies that although CBF1 is present in cells with silent Cp and LMP2Ap, in the absence of EBNA 2 it does not bind to its recognition sites.

Herpes Simplex Resistance History

Acyclovir (ACV) is the gold standard for the treatment of HSV infections. This drug is a nucleoside analogue of guanosine that has to be phosphorylated three times. The first phosphorylation is achieved by the thymidine kinase (TK) encoded by the virus this step is important as it allows ACV to become active only in infected cells. The second and third phosphorylations are carried out by cellular thymidylate kinases. Acyclovir triphosphate is a competitive inhibitor of viral DNA polymerase and is a DNA chain terminator. 1 Herpes simplex virus strains resistant to ACV have been reported since 1982. 2 They were most often recovered from immunocompromised patients previously treated with ACV. 3 Herpes simplex virus resistance to ACV may be associated with a mutation in one of the two viral enzymes involved in ACV mechanism of action TK and or DNA polymerase. Mutations occurring in the viral gene encoding TK are the most frequent and 95 of ACV-resistant isolates present a TK-deficient...

Quantitative Taq Man Assay for the Detection and Monitoring of Cytomegalovirus Infection in Organ Transplant Patients

Quantitative polymerase chain reaction assays have become the most common methods in the determination of viral load during cytomegalovirus (CMV) infection of transplant patients. In recent years, the development of automated nucleic acid extraction devices together with the introduction of real-time technology have been important elements for improvements of these assays. Key Words Automated nucleic acid extraction cytomegalovirus (CMV) MagNA Pure LC organ transplant patient plasma quantitation real-time PCR TaqMan viral load. Over the past recent years, the knowledge of the clinical significance, diagnosis, and management of cytomegalovirus (CMV) infection and disease in transplant patients has increased considerably. Major advances have been achieved through the development of new diagnostic techniques for the detection of the virus and through the use of antiviral agents. Most centers have protocols for the frequent monitoring of transplant recipients for CMV and 1. Human...

Herpesvirus Saimiri and Herpesvirus Ateles

This section focuses on the basic biology, gene content, and viral mechanisms of oncogenic transformation of HVS and HVA, and their possible applications as T-cell vectors and in cell-based immunotherapy. These gamma-herpesviruses must not be confused with two alphaher-pesviruses isolated from the same host species, designated as species Saimiriine herpesvirus 1 and Ateline herpesvirus 1, respectively. HVA can be isolated at a high frequency from spider monkeys (Ateles spp.). Strain 810 from A. geoffroyii is a member of species Ateline herpesvirus 2, whereas strain 73 and related strains (87, 93, and 94) from A. paniscus are isolates of ateline herpesvirus 3. HVA replicates in OMK cells, but remains mostly cell-associated with syncytia formation. As a result, supernatants of such cultures have low, unstable virus titers. In all gammaherpesviruses, the genes that are conserved among the herpesvirus subfamilies are arranged in blocks. Flanking or interspersed among the blocks are other...

Other Nonprimate Cytomegaloviruses

Swine cytomegalovirus is endemic in swine herds worldwide, and has also been shown to reactivate from pig-to-baboon xenotransplants. It causes rhinitis in young swine and is able to cross the placenta, resulting in generalized disease, runting, and fetal death. Initial sequence analysis of the DNA polymerase complex genes suggests that this virus is more closely related to HHV-6 than to CMVs. Tree shrew herpesvirus has been sequenced and has been found to resemble MCMV and other betaher-pesviruses. A CMV has been isolated from deer mice (Peromyscus maniculatas) in North America, and has been characterized as a CMV based on physical and biological properties and genetic homology with several genes of other CMVs. CMVs have also been isolated from European and American ground squirrels, and designated as sciurid herpesvirus 1 and sciurid herpesvirus 2, respectively. See also Cytomegaloviruses Simian Cytomegalo-viruses Herpesviruses General Features Human Cyto-megalovirus General Features...

Conditions That May Simulate Herpes Zoster

Herpes Simplex HSV in a linear distribution may be clinically impossible to distinguish from herpes zoster. Linear lesions are more common in children and with HSV on the extremities. Groups of lesions in different stages of evolution and pain or dysesthesia favor zoster. Culture, RIF, and PCR testing will distinguish the two.

Murine Cytomegalovirus

Images Cmv Virus Strand

Murid herpesvirus 1 is the type species of the genus Muromegalovirus. The term murine cytomegalovirus (MCMV) is more commonly used for the virus than murid herpesvirus 1. The natural host for MCMV is the house mouse, Mus musculus domesticus. Because of the strict species specificity of CMVs, MCMV is widely used as an animal model of HCMV infection. Consequently, more is known about MCMV than any other nonprimate CMV. The viral capsid is composed of 162 capsomers comprising hexons and pentons in a T 16 icosohedral lattice structure. The capsids of CMVs are larger and incorporate a larger genome than other herpesviruses. Unlike other CMVs, MCMV preparations may contain a high proportion of multicapsid virions, which contain a number of capsids enclosed within a common membrane. The capsid of MCMV is composed of five proteins the major capsid protein (MCP), the minor capsid protein, the minor capsid binding protein, the smallest capsid protein, and an assembly protease. These are encoded...

Panherpes PCR with Degenerate Primers

The method is based on the fact that herpesvirus genomes contain highly conserved genes, which are present in all because they code for proteins essential for viral growth. One of the most conserved is the herpesvirus DNA polymerase (DPOL) gene. Investigators aligned the DPOL genes of all herpesviruses for which sequence data were available, in order to identify short blocks of greatest amino acid identity that encode domains essential for DPOL function. This procedure allowed the design of five degenerate primers that were used in a nested PCR -three primers in the first round and two primers in the second round (Figure 1). The region amplified in between the primers displayed a lower degree of conservation. This allowed investigators to assess (1) whether the detected herpesvirus was known or novel, and (2) to which herpesvirus subfamily the novel species could be assigned. In some cases, even a tentative assignment to a virus genus was possible. The primers are degenerate in their...

History of Herpesvirus Discovery

Diseases caused by herpesviruses have been known since ancient times, but it was not until the beginning of the twentieth century that the viruses causing these diseases were detected. Human alphaherpesviruses (members of subfamily Alphaherpesvirinae) such as herpes simplex virus (HSV) and varicella-zoster virus (VZV) were the first to be propagated in cell culture and visualized by electron microscopy. Later, betaherpesviruses (members of subfamily Betaherpesvirinae) such as human cytomegalovirus (HCMV) and gammaherpesviruses (members of subfamily Gammaherpesvirinae) such as Epstein-Barr virus (EBV) were discovered and studied in detail. EBV was the first herpesvirus whose genome was cloned in bacteria and completely sequenced. In the middle of the last decade of the twentieth century, the complete genome sequences of roughly 40 herpesvirus species had accumulated in public databases. These human and animal her-pesviruses had previously all been cultured, and their physical,...

Epigenetic Modifications of aHerpesvirus Genomes

A-Herpesviruses have a relatively short reproductive cycle and their productive (lytic) replication results in destruction of the infected cells. In vitro they spread rapidly after infection in sensitive cell types. In vivo they establish latency first in sensory ganglia and in cells of the central nervous system, although equine herpesvirus 1 and equine herpesvirus 4 target the lymphoretic-ular system (Welch et al. 1992) and latent Marek's disease virus genomes are associated with lymphomas in chicken (reviewed by Morimura et al. 1998). T lymphoblastoid cell lines derived from such lymphomas carry methylated viral genomes (Kanamori et al. 1987). The latent genomes of herpes simplex virus are associated with nucleosomes (Deshamne and Fraser 1989) and exist in an extrachromosomal (episomal) state (Mellerick and Fraser 1987). Depending on the host cell, both DNA methylation and modification of histone tails may affect expression of the best-characterized a-herpesvirus genomes.

Herpes and Varicella Zoster

Impetigo Eyelid

INTRODUCTION Herpes zoster (shingles) and varicella zoster (chickenpox) are both systemic infections with manifestations caused by herpes virus varicellae. The virus is an obligate human parasite requiring person-to-person transmission for its survival. Varicella most commonly occurs in children and is almost always a mild, self-limited disease however, when the disease occurs in adults it is often a much more severe process. Zoster, meaning belt or girdle in Greek, is felt to be a reactivation of a previous varicella infection within a single dermatome. Herpes zoster is most prevalent in middle to late adulthood however, it can occur in children and rarely even in infants, in whom it is usually a mild disease. Eyelid symptoms result from involvement of the first or ophthalmic division of the trigeminal (5th cranial) nerve and are seen in up to 10 of cases of zoster infections. Adults with herpes zoster are contagious during the early stages and often transmit the virus to susceptible...

Epigenotypes of Latent Herpesvirus Genomes

2 Epigenetic Modifications of a-Herpesvirus Genomes 64 of a p-Herpesvirus 4 Epigenetic Modifications of Latent y-Herpesvirus Genomes 67 4.1 Methylation Patterns of Herpesvirus Saimiri DNA In Vitro and In Vivo . . 68 4.3 Reactivation of y-Herpesviruses A Dual Role for DNA Methylation 72 in Regulatory Regions of y-Herpesvirus Abstract Epigenotypes are modified cellular or viral genotypes which differ in tran-scriptional activity in spite of having an identical (or nearly identical) DNA sequence. Restricted expression of latent, episomal herpesvirus genomes is also due to epigenetic modifications. There is no virus production (lytic viral replication, associated with the expression of all viral genes) in tight latency. In vitro experiments demonstrated that DNA methylation could influence the activity of latent (and or crucial lytic) promoters of prototype strains belonging to the three herpesvirus subfamilies (a-, p-, and y-herpesviruses). In vivo, however, DNA methylation is not a...

Conditions That May Simulate Herpes Simplex Recidivans

Both diseases are common in the central facial region, and both begin with small clear vesicles on an inflammatory base. Herpetic lesions tend to remain fixed and discrete, and the vesicles are small, 1 to 2 mm across, tightly grouped, and persist for longer periods. Facial HSV occasionally develops secondary impetigo, causing some diagnostic confusion. A smear with a Gram stain will often show bacteria with cases of impetigo. A Tzanck smear of a blister base will show herpes virus cytopathic effect with herpes labialis. RIF test is also positive with herpes. Bacterial and viral cultures are expensive and are seldom justified. Differentiation of herpetic and bacterial lesions in periungual locations requires a high index of suspicion. The thick epidermis in these acral areas disguises the morphology of the herpetic lesion, which usually presents as an acute inflammatory pustule. Viral lymphangitis is common. Clear unilocular or multilocular vesicles should suggest herpes. Recurrent...

Classification of Cytomegaloviruses

Cytomegaloviruses (CMVs) are large, enveloped, double-stranded DNA viruses with an icosahedral capsid that belong to subfamily Betaherpesvirinae of the family Herpesviridae. There are three genera. Genus Cytomegalovirus contains human cytomegalovirus (HCMV species Human herpesvirus 5) and a number of other primate CMVs. Genus Muromegalovirus contains murine cytomegalovirus (MCMV Murid herpesvirus 1) and rat cytomegalovirus (RCMV Murid herpesvirus 2). Genus Roseolovirus contains human herpesviruses 6 and 7 (HHV-6 and HHV-7 Human herpesvirus 6 and Human herpesvirus 7). Other CMVs that have not yet been fully classified within the Betaherpesvirinae are guinea pig cytomegalovirus (GPCMV Caviid herpesvirus 2), tree shrew herpesvirus (THV Tupaiid herpesvirus 1), swine cytomegalovirus (SuHV-2 suid herpesvirus 2), European ground squirrel cytomegalovirus (ScHV-1 sciurid herpes-virus 1), and American ground squirrel cytomegalovirus (ScHV-2 sciurid herpesvirus 2). Herpesviridae Murid...

Herpes ZosterDRG Category 272

I I erpes zoster, also known as shingles, is a common viral skin eruption that is estimated to affect 300,000 to 500,000 persons a year in the United States. Approximately 95 of adults in the United States have antibodies to the varicella zoster virus (VZV), which means they have been exposed to it. The virus causes acute unilateral inflammation of a dorsal root ganglion. Each nerve innervates a particular skin area on the body called a dermatome, which bends around the body in a pattern that has been mapped corresponding to the vertebral source. Generally, herpes zoster eruptions occur in the thoracic region and, less commonly, affect a single cervical, facial (trigeminal nerve), lumbar, or sacral ganglion. 422 Herpes Zoster (Shingles)

The Herpesvirus Model

Additional features characteristic of latent infections can be identified through a more detailed consideration of latent infections engendered by the herpes simplex virus and Epstein-Barr virus (EBV). The herpesviruses, particularly herpes simplex virus, are the classic examples of latent agents, and latent infections are basic to their natural history. Hepadnavirus Hepatocytes, Herpesviruses (a) Herpes simplex 1 and 2 Neurons Episomal No macrophages (e) Human herpesviruses 6,7,8 Probably T lymphocytes Papillomaviruses Keratinizing epithelial cells Integrated and episomal No Parvoviruses Epithelial cells Integrated No Polyomaviruses Probably integrated Probably Retroviruses Herpes simplex virus The relevant pathogenesis of herpes simplex virus involves infection and viral replication at the body surface, followed by the passage of the virus (or, more probably, the viral nucleocapsid) to the regional sensory ganglion by fast axonal transport in the associated sensory nerve. At this...

Herpesvirus Vectors

Two herpesviruses are emerging as alternatives for the development of gene transfer vectors herpes simplex virus (HSV) and Epstein-Barr virus (EBV). HSV has a genome of approximately 155 kb in length, which is maintained as a concatemerized circular or linear episome in infected cells. It efficiently infects cells, including nondividing cells, from a wide variety of organisms, and is able to establish a persistent infection. Its genome can accommodate large amounts of foreign DNA, and a number of vector systems have been developed. The EBV-based systems have not been developed as extensively and currently employ replication-defective EBV strains. Unlike HSV, EBV vectors have a very limited tropism and their possible usefulness remains to be explored. The main difficulty using these two systems is the need for almost complete virus genomes that are very complex and large in size, making manipulations exceedingly difficult. The eventual usefulness of these systems will be dictated by...

HSV Infection during Pregnancy and Neonatal Disease

Localized genital infection is the most common form of HSV infection during pregnancy. In a small number of patients multiple visceral sites are also involved. Mortality among these pregnant women was reported to be > 50 , presumably due to altered cell-mediated immune responses. Fetal deaths occurred in 50 of cases, although mortality did not correlate with the death of the mother. Severe intrauterine fetal growth retardation was reported in women with primary HSV infection during pregnancy. Maternal primary infection before 20 weeks of gestation was associated with spontaneous abortion in as much as 25 of infected women. Fetal infection is generally due to virus shed at the time of delivery. Neonates have the highest frequency of visceral and CNS involvement of all HSV-infected patients. Skin lesions are the most commonly recognized features of the disease. However, at least 70 of untreated neonatal HSV cases will lead to

Herpes SimplexDRG Categr 283

There are two types of herpes simplex virus (HSV), type 1 and type 2. HSV-1 causes infection above the waist, such as cold sores that occur on the mouth. This type may occur in the genital area as a result of oral-genital sexual practices. After the initial infection, the virus is dormant, but the patient is a carrier and likely to have recurrent infections. Events that trigger recurrences are sun exposure, fever, menses, stress, or lack of sleep. Active HSV is associated with spontaneous abortion in the first trimester of pregnancy and an increased risk of preterm labor after 20 weeks' gestation. If a patient has active herpes around the time of the estimated date of delivery, cesarean section is the preferred method of delivery. Infected infants can develop the following signs and symptoms after an incubation period of 2 to 12 days fever, hypothermia, jaundice, seizures, poor feeding, and vesicular skin lesions.

Methylation Patterns of Herpesvirus Saimiri DNA In Vitro and In Vivo

Herpesvirus saimiri causes lymphoma or leukemia in certain New World primates. The virion DNA was found to be unmethylated (Desrosiers 1982), but methylated viral DNA molecules were detected in lymphoid tumor cell lines (Desrosiers et al. 1979) and in DNA samples isolated from peripheral blood of one owl monkey and three white-lipped marmosets with leukemia (Desrosiers 1982). This suggests that de novo methylation of the viral genomes occurred in vivo and was not a result of prolonged in vitro cultivation of the tumor cells. Using CpG methylation-sensitive and resistant isoschizomers, an unmethylated region was also mapped in viral genomes carried by a cell line established from a marmoset tumor (Desrosiers 1982).

Reactivation of yHerpesviruses A Dual Role for DNA Methylation

Productive (lytic) replication of herpesviruses can be induced in cells carrying latent viral genomes by activation of IE genes. IE gene products activate thereafter transcription of lytic viral genes in a cascade-like manner. The promoter for the 0RF50 gene encoding Lyta (KSHV Rta), an IE protein of Kaposi's sarcoma-associated herpesvirus (KSHV human herpesvirus 8), was heavily methylated in primary effusion lymphoma (PEL)-derived cell lines during latency, but induction of the lytic cycle by 12- O-tetradecanoylphorbol-13-acetate (TPA) caused Lyta promoter demethylation (Chen et al. 2001). This suggests that KSHV maintains latency by controlling (repressing) the activity of a key promoter, Lyta, via DNA methylation. In contrast, demethylation impairs activation of Rp, the IE promoter for the BRLF1 gene of EBV, by the IE protein BZLF1 (Z) (Bhende et al. 2004). Bhende et al. suggest that preferential

How Many Herpesviruses Have Been Discovered

Since the publication ofthese methods, the number ofnovel herpesviruses discovered has risen very fast. Prior to writing this article, more than 200 potential herpesvirus species had been detected, belonging to more than 20 mammalian orders (Table 1). These are many more than currently accepted by the International Committee on Taxonomy of Viruses (ICTV), which lists some 120 herpesvirus species (Vlllth Report). Sequences of more than 160 herpesviruses are available under the taxonomy browser of the NCBI, most detected by DPOL consensus primers. In addition, sequences indicating the existence of more than 100 additional herpesvirus species, not yet available in public databases, await publication. By combining all the data currently available, a total of approximately 300 detected

Epigenetic Modifications Regulate the Activity of a pHerpesvirus Promoter

P-Herpesviruses are highly species-specific viruses that grow slowly in cultured cells. The site(s) of residence for p-herpesviruses (monocytes and their bone marrow progenitors, endothelial cells) is still a subject of intensive research. Infection with human cytomegalovirus (HCMV, human herpesvirus 5, the best-characterized p-herpesvirus) and similar viruses isolated from other primates, domestic animals, and rodents causes typical cytopathologic changes involving cell enlargement. Honess et al. analyzed dinucleotide frequencies in herpesvirus DNA and observed a local deficiency of CpG dinucleotides in the major IE genes of hu man, murine, and simian cytomegalovirus genomes (Honess et al. 1989). The complete genome of human and murine cytomegalovirus is not CpG deficient as a matter of fact, the observed CpG frequency is higher than the expected one (Takacs et al. 2001b). Because a relative CpG deficiency and a surplus of TpG+CpA dinucleotides is thought to be a consequence of DNA...

Herpesviruses

Herpes-like virus infections have been identified in various marine mollusk species throughout the world, including the USA, Mexico, France, Spain, the UK, New Zealand, Australia, and Taiwan. The first description of a virus morphologically similar to members of the family Herpes-viridae in a bivalve mollusk was reported in 1972 in the eastern oyster, Crassostrea virginica. Since then, a wide host range has been reported for herpes and herpes-like viruses infecting bivalve species, including the Pacific oyster C. gigas, the European oyster Ostrea edulis, the Antipodean flat oyster Ostrea angasi, the Chilean oyster Tiostrea chilensis, the Manila clam Ruditapes philippinarum, the carpet shell clam Ruditapes decussatus, the Portuguese oyster C. angulata, the Suminoe oyster C. ariakensis, and the French scallop Pecten maximus. It is noteworthy that recently a herpes-like virus has also been observed by transmission electron microscopy in the gastropod mollusk Haliotis diversicolor...

Herpes Simplex

Eosiniphlic Keratynocytes

INTRODUCTION Herpes simplex is caused by a DNA virus that is estimated to infect 60 to 90 of individuals at sometime during their life. Clinically evident infections however are much less common. Involvement of the facial region is predominantly due to type I herpes virus, with the exception of newborns, in whom overwhelming exposure to the type II variety during birth can result in development of typical skin lesions during the first few days of life, often associated with devastating CNS and systemic involvement. Primary herpes occurs in previously uninfected individuals. The chief mode of transmission is by kissing or other forms of intimate contact with an individual who has an active, usually recurrent, herpetic lesion. CLINICAL PRESENTATION Following a 2 to 14 day incubation period there develops a mild fever with moderately painful, usually unilateral, edema and erythema of the eyelid region. This is soon followed by the development of multiple discrete 2 to 3 mm vesicles that...

Herpesviridae

Herpesviruses have been isolated from channel catfish (Ictalurus punctatus), common and koi carp (C. carpio), common goldfish ( Carassius auratus), eel (Anguilla spp.), rainbow trout, masou salmon, lake trout (S. namaycush), sturgeon, walleye, and Japanese flounder. Channel catfish virus is the only fish herpesvirus assigned to the genus, Ictalurivirus, and this genus is not assigned to any of the three subfamilies (Alphaherpesvirinae, Betaherpesvirinae, and Gammaherpesviri-nae) of the family Herpesviridae. The other fish herpesviruses, cyprinid herpesviruses 1 and 2 (CyHV-1 and CyHV-2), koi herpesvirus (CyHV-3), salmonid herpesvirus 1 and 2 (SalHV-1 and -2), eel herpesvirus (Anguilla herpesvirus, AngHV-1), and the acipenserid or white sturgeon herpesviruses remain as unassigned members of the family Herpesviridae. Electron micrographic evidence of herpes-viruses has been found in sharks, eels, pike, flounder, perch, angelfish, grouper, and other fish. The genomes of fish...

IHerpesviridae

Isolated similar viruses from patients with acquired immune deficiency syndrome (AIDS) and children with exanthem subitum, and revealed that the virus is predominantly T lymphotropic. The name of the virus was changed to human herpesvirus 6 because it was a newly discovered one distinguished from other five known human herpesviruses. HHV-6 isolates are classified into two groups as variants A (HHV-6A) and B (HHV-6B). The two variants are closely related but show consistent differences in biological, immunological, epidemiological and molecular properties. HHV-6B is the major causative agent of exanthem subitum, but no disease has yet been associated with HHV-6A. HHV-7 was isolated by Frenkel et al in 1990, as the seventh human herpesvirus, from CD44- lymphocytes of a healthy adult. The virus also causes exanthem subitum.

Virion and Genome Structure and Composition

As indicated by the size and complexity of the virions, the genome of ascoviruses is large, and consists of a single molecule of dsDNA, which, depending on the viral species, is either in the range of 116 kb in size (Diadromus ascovirus), 140 kb (Spodoptera ascovirus) or 180 kb (Trichoplusia ascovirus). The G + C content of the Spodoptera ascovirus is 60 , whereas for the Trichoplusia ascovirus it is 42 . Supercoiled circular DNA has not been detected in cesium chloride gradients, nor have circular forms been observed by electron microscopy. The DNA genome is therefore referred to as linear, though each terminus may consist of a short single-stranded loop connecting the stands, making the molecule circular, as occurs in herpes-

Replication and Morphogenesis

Though there have been no biochemical studies of viral DNA replication or protein synthesis, studies carried out with the Trichoplusia and Spodoptera ascoviruses in vitro in insect cell lines show that progeny virions first appear about 12 h after infection. Virion morphogenesis is initiated after the nucleus ruptures, and occurs before and during the cleavage of the cell into vesicles. The first recognizable structural component of the virion to form is the multilaminar layer of the inner particle. Based on its ultrastructure, this layer consists of a unit membrane and an exterior layer of protein subunits. As the multilaminar layer assembles, a dense nucleoprotein core aggregates on the interior surface. This process continues until the inner particle is complete. After formation, the inner particle is enveloped by membranes within the cell or vesicle. These membranes are apparently synthesized de novo. Thus, the assembly of the virions is reminiscent of that in other viruses with...

Future Perspectives

Some of the initial studies on molecular mimicry and virus-induced autoimmunity indicated that viruses share common sequences with host components. It has been demonstrated that some viruses have acquired host genes and modified these to subvert the immune system. Herpesviruses encode MHC-like molecules, Fc receptors, IL-10-like factor and complement regulatory proteins, and poxviruses have incorporated into their genome, IL-1 receptor, tumor necrosis factor (TNF) receptor, IFN-y receptors and complement control proteins. In addition, viral proteins need to perform specific functions in the cell to replicate its genome and assemble new virions. These functions use the existing cellular machinery and therefore mimic many of the host cells, which also perform similar tasks. The key question is still how are these infections which are associated with autoimmune disease able to initiate the pathway leading to self-reactive immune responses

Prevention and Control

Malignant catarrhal fever, since it is acquired from a second, heterologous host (wildebeest, sheep), is clearly preventable by avoiding contact. The sporadic nature of the disease and the lack of detailed knowledge of the putative sheep-associated virus make avoidance difficult. In zoo collections bovid species known to harbor alcelaphine herpesviruses 1 and 2 should not be cohabited with those species known to be susceptible to malignant catarrhal fever. There is considerable interest in the molecular biology of the bovine herpesviruses the entire nucleotide sequence of BHVl has been determined, and substantial amounts of the genomes of BHV4 and alcelaphine herpesvirus 1 have also been sequenced. Characterization of the transcripts and proteins of the viruses continues. Progress in developing better vaccines and diagnostic reagents for BHVl based on recombinant DNA technologies, including DNA vaccines, is continuing. The unusual epidemiologies of BHV2 and BHV5 are matters for future...

Evolutionary Conservation Of Bcl2 Family Proteins

Notably, this family of proteins is evolutionarily conserved. A number of viruses encode Bcl-2 homologs, including most, if not all, gamma herpes viruses (7). Most of these viral homologs are anti-apoptotic, probably because viruses need to keep the infected cells alive for latent and persistent infection (7,8). The nematode Caenorhabditis elegans has its own sequence and functional homologs for a death antagonist, CED-9 (9), and a BH3-only death agonist, EGL-1 (10). On the other hand, only prodeath homologs (dBorg-1 Drob-1 Debcl and dBorg-2 Buffy) have been described in the Drosophila (11). These homologs are discussed in details in Chapters 9 and 10, respectively.

History and Classification

Level but distinct crossneutralization of CHP and Piry viruses with VSV-IND was previously reported. However, subsequent studies using hyperimmune guinea pig as well as rabbit serum failed to detect any crossreactivity between these viruses, even when the infective ribonucleoprotein (RNP) particles were used, indicating that these viruses possess distinct antigenic determinants. The Piry virus constituent proteins were also found to be antigenically distinct from several other viruses such as lymphocytic choriomeningitis virus, herpes simplex virus, and 62 arboviruses.

The Major Breakthrough

The discovery of the antiherpes drug, acyclovir (ACV) in 1978, was the major milestone in antiviral therapy. For the first time, it was demonstrated that an effective, non-toxic, antiviral drug is an achievable aim. Moreover, chronic suppressive acyclovir therapy for several years, to prevent the misery of recurrent herpes, is possible without adverse effects. More than two decades of worldwide use has proved that acyclovir is one of the safest drugs in clinical therapy. Acyclovir proved that not all nucleoside analogs had to be mutagenic and or carcinogenic. The early doubts, about the potential for discovering safe antiviral agents, were dispelled for ever. The selectivity of acyclovir for the herpes viruses is dependent on it being activated only in herpes virus-infected cells. The critical initial step in that activation is its phosphorylation to ACV-monophosphate by the viral thymidine kinase. Cellular enzymes convert the monophosphate to the triphosphate which inhibits...

Gene Targeting And Knockout Genetics

The next question (of course) was to find in which cells this rare event was happening. In order to answer this question markers which could be detected in cell culture were inserted into the targeting vector. These markers can take several forms. In Figure 5.24 the markers are the 'neomycin resistance' (neor) gene without its promoter so that its expression depended on the targeted gene's promoter and (at the end of the base sequence) the thymidine kinase (tk) gene from the herpes virus. Whilst the neor is inserted into the centre of one of the targeting vector's exons, tk is attached at the end (Figure 5.24). It is known that terminal sequences are usually lost in homologous recombination. When the targeting vector finds its homologue on the culture cell's chromosome the integration events slot the homologous DNA into the host chromosome and eliminate or at least inactivate the tk. In the random case the entire sequence, including tk, is inserted into the host chromosome.

Classification and Evolution

All of the animal CMVs described to date are members of the family Herpesviridae and belong to the Betaherpesvirinae subfamily of herpesviruses. Based on the relatively high (G+C) content of their DNA molecules and their adaptability to grow in fibroblasts in cell culture, most if not all of the traditionally recognized animal CMVs are likely to be evolutionarily more similar to the beta-1 subgroup that includes HCMV and MCMV than to the (A+T)-rich beta-2 subgroup exemplified by HHV-6. The International Committe on Taxonomy of Viruses has now classified betaherpesviruses into three distinct genera, Cytomegalovirus (HCMV-like), Muromega-lovirus (MCMV-like) and Roseolovirus (HHV-6, HHV-7), but it is likely that distinctions between the first two taxons at least will become murky when molecular genetic criteria (i.e. gene content and DNA and protein sequence similarities) are applied to those CMV species that infect other mammalian and primate hosts. The genomes of prototype species of...

Control of Gene Expression

The lytic cycle pathway of gene expression for animal CMVs follows the typical herpesvirus cascade of immediate early mRNA and proteins followed by activation of delayed early then late class genes. Similarly organized MIE transcription units, which encode regulatory proteins that trigger the lytic cycle, have been characterized in HCMV, ChCMV, AgCMV, RhCMV, BaCMV, GpCMV, RCMV, MCMV, and HHV-6 and HHV-7. In each case, these transcription units are oriented leftwards at genome map position 0.7 and produce several multiply-spliced mRNAs whose expression is controlled by powerful upstream cis-acting enhancer control regions. By far the most predominant viral mRNAs synthesized after infection of permissive cells in the presence of cycloheximide are these MIE mRNAs, which are also the only HCMV or AgCMV mRNAs and proteins produced after infection of nonpermissive rodent fibroblasts. At least two types of phosphorylated nuclear regulatory proteins are encoded by the MIE transcription unit....

Properties and Organization of Genome

DNA isolated from purified virions contains a single 3' nucleotide extension that may facilitate circularization to a prereplicative intermediate. Herpesvirus genomes are grouped (A F) according to sequence reiterations greater than 100 base pairs. Based on this scheme, the MCMV genome, consisting primarily of unique sequences, is catalogued with the group F genomes. However, clusters of 31-bp direct repeats delimit each terminus of the genome, and additional, nonhomologous, intra- and intergenic direct repeats punctuate the centralized unique region. Inverted repeats, present in the origin of replication and upstream of several ORFs, do not mediate isomerization.

Taxonomy and Classification

The formal designation given by the International Committee on Taxonomy of Viruses to human CMV is human herpesvirus 5 (HHV-5), a name that is not in common usage. Human CMV is the prototype of the genus Cytomegalovirus. Cytomegaloviruses share many characteristics with other herpesviruses, including typical virion morphology and large, linear DNA genome, as well as common biological properties such as persistence and latency in the host. These viruses have distinguishing characteristics as well, such as their well-established tropism for salivary glands, restriction to the host species of origin and slow growth in culture. These differentiating characteristics define the Betaherpesvirinae subfamily. In addition to the cytomegaloviruses, genome sequence analysis established that the betaherpesviruses include two lymphotropic human herpesviruses, HHV-6 (genus Roseolovirus) and HHV-7. Large-scale nucleotide sequence analysis of human CMV, murine CMV, HHV-6 and HHV-7 demonstrated a...

Properties of the Virion

Typical of the herpesvirus group, the virion of huma cytomegalovirus (HCMV, human herpesvirus 5). is approximately 230 nm in diameter and is composed of a DNA-containing nucleocapsid, surrounded by a less structured tegument layer, and bounded by a trilami-nate membrane envelope. The nucleocapsid is icosa-hedral has an outside diameter of approximately sensitive to a compound, ganciclovir DHPG), that is structurally related to acyclovir but acts via a poorly understood process whereby another viral kinase (UL97) is responsible for its phosphorylation. Ganciclovir is administered parenterally or, at very high doses, orally and can control CMV infections. Because of the chronic immunocompromised settings where CMV emerges as a pathogen, prolonged treatment is often necessary and this leads to the emergence of drug-resistant mutants due to mutations in the UL97 kinase or the DNA polymerase. Another parenterally administered nucleotide analogue, cido-fovir has also been licensed for use...

Properties of the Proteins

HCMV proteins share the general pattern of expression characteristic of the herpesvirus group. Immediate early (a), early ( ) and late (y) proteins are synthesized sequentially from corresponding mRNAs whose transcription is regulated in a temporal cascade (see Characterization of Transcription below). Immediate early proteins are required to regulate transcription from their own promoters and those of subsequently expressed genes. Early proteins include many of the enzymes and regulatory factors needed to carry out the synthesis of progeny DNA and proteins. Late proteins include most of the virion structural proteins. Members of all three classes have been described for HCMV, but only a small number of its more than 200 potential proteins have been identified. Those that have been reported include both nonvirion and virion species and their properties are briefly described below.

Temporal Regulation of Transcription

Viral gene knockouts have shown that either IE1 or IE0 is essential for viral replication and in the absence of this gene no viral infection is initiated. IE1 0 is an acidic domain transcriptional transactivator, similar to the herpesvirus VP16 protein and activates viral gene transcription by both enhancer-dependent and independent mechanisms. IE1 0 forms dimers that bind to the hr sequences which serve as the transcription enhancers. IE1 0 is also essential for the viral replication complex where it is believed to play the role of an origin binding protein. In support of this, it has been shown that a transcriptionally inactive OpMNPV IE1 is able to support transient viral DNA replication.

Pathology and Histopathology

Respiratory disease caused by EHV-1 and EHV-4 results in inflammation, congestion, and sometimes necrosis of the tissues of the upper respiratory tract. Extensive swelling of the nasal mucosa may occur and, in later stages, the lungs may become involved. One can find typical herpesvirus inclusion bodies in the nuclei of the respiratory epithelium. The respiratory infection can

Host Range and Virus Propagation

Although the horse is the natural host of the equine herpesviruses, a variety of animals and tissue culture systems can be used to propagate the viruses. Regarding the major equine pathogen, EHV-1, experimental animals include Syrian hamsters and baby hamsters, chick embryos, baby mice and adult mice, and kittens. Primary tissue culture systems used to propagate EHV-1 include cells from a variety of equine tissues such as fetal lung, dermis, spleen and kidney, as well as cells from domestic cats, dogs, hamsters, rabbits,

Dl Particles and Persistent Infection

Altered outcomes of equine herpesvirus infections have been reported and include oncogenic transformation (EHV-1, EHV-2, EHV-3, and EHV-5) and persistent infection (EHV-1, EHV-2, and EHV-5). EHV-1 persistent infection and oncogenic transformation in vitro were shown to be mediated by virus preparations enriched for EHV-1 DI particles (DIPs). EHV-1 DI particles have been generated in vivo in the Syrian hamster model, and therefore DIPS may be generated in EHV-1 infection of the natural host. The DIPs are replication defective and require the standard virus as a helper. The majority of EHV-1 DNA sequences have been deleted from the genome of EHV-1 DIPs, such that sequences from three regions of the EHV-1 genome are conserved in the DIP genome. These three segments are (1) the L-terminus, including genes UL1, UL2 and the 3' portion of UL3-,

Management Of Ebvassociated Diseases

Most cases of infectious mononucleosis do not require therapeutic intervention. In cases of clinically severe IM and life-threatening forms of SCAEBV, intravenous application of the nucleoside analog acyclovir or gancy-clovir may be necessary to reduce active viral replica-tion. 4 In addition, but not alone, antiphlogistic drugs to reduce the unspecific effects of the cellular immune response may be beneficial. Tonsillectomy is frequently used and was found to reduce symptoms of IM possibly

Geographic Distribution

Increasing numbers of gammaherpesviruses have been identified in normally free-ranging (exotic) ruminant species that have been farmed or held in zoological collections, and several of these viruses have caused MCF-like syndromes when transmitted to other in-contact ruminant species. At least six members of the MCF virus group of ruminant gammaherpesviruses have been identified thus far. Four of these viruses are clearly associated with clinical disease alcelaphine herpesvirus 1 (AlHV-1) carried by wildebeest (Connochaetes spp.) ovine herpesvirus 2 (OvHV-2), ubiquitous in domestic sheep caprine herpesvirus 2 (CapHV-2), endemic in domestic goats and the virus of unknown origin that caused classic MCF in white-tailed deer (Odocoileus virginianus-, MCFV-WTD). Gammaherpesviruses in the MCF virus group have been found in musk ox (Ovibos moschatus), Nubian ibex (Capra nubiana), and gemsbok (South African oryx, Oryx gazella). Gammaherpesviruses have also been found in bighorn sheep, bison,...

Mapping Viral Genomes

Among viruses that undergo intramolecular recombination, the probability of recombination occurring between two markers reflects the distance between them and recombination frequencies in adjacent intervals are approximately additive. Two-factor crosses are used to determine recombination frequencies between pairs of mutants for very close or distant markers three-factor crosses are used to resolve ambiguities. Recombination maps have been made for several large DNA viruses, notably herpes simplex virus, and for poliovirus. With the determination of nucleotide sequences the genetic markers of a number of viruses have been located on the relevant physical maps.

Enumeration of Absolute Cell Counts Using unit 68 Immunophenotypic Techniques

Enumeration of absolute CD4+ T lymphocyte number continues to be the hallmark laboratory test for staging HIV-infected patients. This is a critical surrogate marker for assessing immunodeficiency. The T cell subset value is an independent marker, yet it complements HIV plasma viral load data. As potent anti-HIV therapies are becoming more effective and complex, the CD4+ T cell levels for diagnostic prognostic staging of patients and therapeutic prophylactic intervention will continue to shift (Johnson et al., 1995 Lane, 1994). However, the utility of the CD4+ T cell count remains unchallenged and critical (Nicholson et al., 1994). The absolute and percent CD4+ T cell count is also of clinical relevance in other immunodeficiency conditions. These include solid-organ transplantation, the post-chemotherapy period, the recovery phase following bone marrow (or stem cell) transplants, therapy with purine nucleosides like 2-chlorodeoxyadenosine (cladribine) for hairy-cell leukemia,...

Virus Replication and Host Range

Naturally, HSV causes disease only in humans. However, it infects experimental animals such as hamsters, mice, rats, guinea pigs, rabbits and embryonated chicken eggs. The animal species, virus type, route of inoculation, and state of immune competence affect the outcome of infection. In the mouse, intracerebral, footpad, intranasal and intraperitoneal inoculations are used as models of human fatal neurological or visceral disease. Eye infection is used as a model of encephalitic and latent disease. Certain mouse strains (e.g. C57BL 6) exhibit natural resistance to HSV infection whereas newborn mice are particularly sensitive. HSV-1 infection of the skin was described in mice, rabbits and guinea pigs following skin abrasion or intradermal inoculation. HSV-2 mucosal infections have been studied in the mouse and the guinea pig. The best approximation of human recurrent cutaneous disease was achieved in the guinea pig. A wide variety of cell lines support HSV growth. Primary and...

Immortalization of Macrophagelike Cells In Vitro

As herpesvirus sylvilagus induces a lymphoma-like disease, it infects both B and T cells in vivo, and these cells contain episomal viral genomes typically seen in cells immortalized with herpesviruses. Several laboratories investigated immortalization of lymphoid cells with the virus. All of the in vitro and in vivo attempts (published or unpublished) failed, except for a report on a 'macrophage-like' rabbit cell line established by in vitro infection of splenocytes with herpesvirus sylvilagus. This cell line contained integrated herpesvirus sylvilagus DNA. Lymphoid cell lines immortalized with other herpesviruses such as EBV or herpesvirus saimiri typically carry multiple copies of episomal viral genomes and integration seldom occurs. These basically negative results do not rule out the possibility that herpesvirus sylvilagus can immortalize lymphocytes for example, infected cells may require special growth factors and lymphokines for in vitro culturing. To resolve the issue of the...

Geographic and Seasonal Distribution

Herpesvirus papio, herpesvirus pan, SA8 (and related strains) are all natural to African species and in nature are restricted to that continent. However, baboons and chimpanzees have been transported throughout the world and as herpesviruses have a propensity for latency, they may be found wherever baboons and chimpanzees are located and without any seasonal distribution. In the Sukhumi colony, however, peak infection with herpesvirus papio occurred in the autumn and spring.

Clinical Features of Infection

In the original studies by Lapin and his collaborators, the observed clinical disease associated with herpesvirus papio infection included a wide variety of lymphomas non-Hodgkin's lymphoma of the lymphoid type (predominantly) lymphosarcoma prolymphocytic lymphosarcoma reticulosarcoma lymphoplasmacytic, immunoblastic lymphoma and lymphogranulomatosis. Herpesvirus pan is endemic in its natural host, the chimpanzee, without any evidence of clinical disease. Limited experimental infection with this virus has also shown no capacity to produce disease.

Properties of the Genome

The genomes of HHV-6 and HHV-7 are linear double-stranded DNA molecules of approximately 159 kb and 145 kb, respectively. The gene organization of each is illustrated in Fig. 1. The complete genomic sequences were determined for HHV-6A strain U1102 and HHV-7 strain JI, and partial sequences were reported for other strains, including HHV-6B strain HST.HHV-6A and HHV-6B are very similar genetically because their nucleotide sequences differ by 4-10 between the variants, depending on the gene being compared. This similarity, which is higher than that for any other independently recognized herpesvirus species, led to the decision to adopt the variants A and B nomenclature, rather than name the variants as distinct species. Sequence comparison among herpesvirus species revealed the highest conservation of genetic content and encoded protein products between HHV-6 and HHV-7, ranging from 41 to 75 amino acid sequence identity for the core herpesvirus gene products. HHV-6A strain U1102 DNA...

Growth and Propagation of Virus in the Laboratory

Each of these New World monkey herpesviruses has a morphology consistent among the agents classified as herpesviruses. Nucleocapsids are formed in the nuclei of infected cells and are approximately 100 nm in diameter, with dense centers. The mature, enveloped particles are slightly larger and located in cytoplasmic vacuoles of infected cells. Glycosylation of envelope proteins occurs within the endoplasmic reticulum and Golgi apparatus to form mature virions. HVS-2 grows well in primary cells derived from New World monkeys but less efficiently in those derived from Old World monkeys, while HVA-2 grows well in a variety of epithelial and fibroblast cells from New World monkeys as well as African green monkeys (Old World monkeys). The spider monkey virus generally replicates to a lower titer in cell culture than the squirrel monkey herpesvirus. In vitro, HVA-2 is capable of immortalizing a variety of lymphoid cells from New World primates, whereas there has been more difficulty using...

Summary and Future Perspectives

Each of these Rhadinovirus members of the family Herpesviridae has immense potential for use as a tool to transform immortalize target cells of interest, particularly with respect to studies of human immunodeficiency virus (HIV) and AIDS. Gene-specific transformation or immortalization of cells is also possible, reducing the input of the nonessential viral genes against the background of the transfected cells. Transformation-associated genes represent a novel class of viral oncogenes which warrant further investigation. Furthermore, each of these virus host systems continues to offer investigators a unique and invaluable avenue for epidemiological studies of virus transmission in nature, both within natural and foreign hosts. Last, but not least, due to the capacity of these viruses for carrying large amounts of DNA inserts, the use of HVS-2 and HVA-2 as novel gene See also Herpesviruses - baboon and chimpanzee (Herpesviridae) Herpes simplex viruses (Herpesviridae)-. General features,...

Methylation Patterns of Latent HSV1 Genomes In Vitro and In Vivo

In a pioneering study, Youssoufian et al. investigated a major epigenetic regulatory mechanism, cytosine methylation (a heritable form of DNA modification) using cells either carrying latent herpes simplex virus type 1 (HSV-1) genomes or undergoing productive infection (Youssoufian et al. 1982). Digestion with cytosine methylation-sensitive and cytosine methylation-resistant restriction enzyme pairs followed by Southern blotting revealed that the latent HSV-1 genomes were highly methylated in cells of a persistently infected lymphoblastoid T cell line (CEM) treated with concanavalin A. In contrast, only unmethylated viral genomes could be detected during productive infection in this reversible in vitro model of viral latency. This study suggested that DNA methylation might play a role in the maintenance of HSV-1 latency.

Infections of Neural Cells

Cell-to-cell spread may also involve axoplasmic flow causing infection of functionally linked cells for example, in poliovirus infections the virus is rapidly spread through the motor system. Some viruses infect only neuronal populations such as rabies, polioviruses, and the arthropod-borne viruses (arboviruses), and some infect selective neuron populations. Other viruses such as herpes simplex virus appear to infect neurons and glial populations with little selectivity.

Pharmacologic Highlights

Acyclovir Relief of symptoms, decreases viral shedding (acyclovir is contraindicated during pregnancy) daily dosage for primary episodes is slightly lower than that used for recurrent infections. Some physicians may order chronic suppressive drug therapy, where acyclovir is taken for up to 6 mo. Inform patients that the risk of acquiring human immunodeficiency virus (HIV) is double that for HSV-2-infected persons. Help the patient understand that this is a minor problem with which she or he will be inconvenienced from time to time. Adherence to strict guidelines when active lesions are present allows the patient to have a normal sexual relationship. Healthcare workers with active herpes are prohibited from working with immunosuppressed patients or in a nursery setting because of the complications that result in the neonate if HSV transmission occurs.

HIV Cellmediated Immunity

The lack of CD4+T cells in patients with AIDS results in much greater susceptibility to a variety of opportunistic infections, particularly those caused by fungi and protozoa. Secondary infections with other viruses are not as prominent, presumably because the CD8+T cell response is less compromised, though infection with herpesviruses may eventually become a problem. Herpesviruses, such as Epstein-Barr virus (EBV) and CMV, tend to persist in sites where they cannot be eliminated by CD8+T cells, though such infections are generally controlled in people who are not immunosuppressed. The severely impaired immune function of AIDS patients reflects the necessity of a complete immune system with many functioning branches.

History or How We Got to Where We

See also Autoimmunity Cytomegaloviruses (Herpesviridae) Animal cytomegaloviruses, General features (human), Molecular biology (human), Murine cytomegaloviruses Epstein-Barr virus (Herpesviridae) General features, Molecular biology Human immunodeficiency viruses (Retro-viridae) Molecular biology, Anti-retroviral agents, General features Influenza viruses (Orthomyxo-viridae) General features, Molecular biology, Structure of antigens Lymphocytic choriomeningitis virus (Arenaviridae) General features, Molecular biology Persistent viral infection Vaccines and immune response Vaccinia virus (Poxviridae), Vectors Animal viruses, Plant viruses.

Detailed Consideration of Dominantnegative Mutants

That a detrimental mutation results in the phenotypic absence of that particular function and that phenotypic rescue can be accomplished by supplying that function in trans are commonly held tenets of genetics. Complementation analysis is based on these assumptions. Interference by dominant-negative mutants may explain some of the difficulties encountered in demonstrating significant complementation. Examples are cited in the literature for several families of DNA and RNA viruses, e.g. herpesvirus HSV-1 and VSV, where co-infection of cells with complementation incompetent mutants interferes with the successful growth of wild-type virus. This test can be used to differentiate dominant-negative mutants from mutants that are complementation incompetent due to alteration in cis-acting functions. In addition to an inhibition of complementation, reassortment of viral genes of segmented RNA viruses can also be affected when one of the two parental viruses is able to dominate the other. Such...

Clinical manifestation

Infection with conjunctival injection and a watery discharge dendritic lesions on fluo-rescein staining of the cornea acute gingi-vostomatitis most frequent clinical presentation of first-episode, primary HSV infection, although most patients have asymptomatic first infection fever (102-104 F) listlessness or irritability inability to eat and or drink gingivitis with markedly swollen, erythematous, bleeding gums occasional increased drooling noted in infants vesicular lesions develop on the tongue, buccal mucosa, and palate, with extension to lips and face tender submandibular or cervical adenopathy disease lasting from 3-7 days recurrent orolabial herpetic infection (herpes labialis) heralded by a prodrome of pain, tingling, burning, or itching, usually lasts up to 6 hours vesicular rash in crops of 3-5 vesicles, frequently arising near the vermillion border recurrences often associated with febrile illnesses, local trauma, sun exposure, or menstruation primary genital infections...

Epidemiology and Physical Properties

Features of host range, virus propagation, virus transmission, tissue tropism, pathogenicity, histopathology, and immune responses of primate CMVs, together with the physical properties and assembly pathways of the virions, and a number of biochemical properties of their structural proteins, closely resemble those of HCMV and MCMV. In general, long-term persistent asymptomatic infection is nearly universal among natural primate populations in the wild, with primary infections occurring in infants and juveniles. Even captive colony-borne animals are rarely free of these viruses, which can be shed intermittently in saliva and urine throughout the host's lifespan. Like all other herpesviruses, primate CMVs have enveloped icosahedral capsids and replicate in the

Viruses that Establish Latent Infections

A list of viruses capable of existing in the latent state is presented in Table 1. Several general statements can be made about this group. First, the kinds of cells involved are many, ranging from immature lymphocytes to terminally differentiated neurons. It should also be stressed that with many viruses, the kinds of cells harboring latent infection are likely to extend beyond those presently appreciated or postulated. Second, features of latent infection now shown only in cell culture systems (for example, integrated sequences of the HIV process) are also likely in the future to be demonstrated in cells taken from infected individuals. Third, in some latent infections, perhaps most notably those involving herpes simplex virus and papillomaviruses, viral-encoded proteins have not been detected in cells harboring the viral DNA. However, transcripts containing potential open reading frames have been found in the former, and transcripts encoding proteins that have been detected in...

Case Definition of AIDSDefining Illnesses

Coccidiomycosis, disseminated or extrapulmonary Microscopy (histology or cytology), culture, or detection of antigen in a specimen obtained affected tissues or a fluid from those tissues. Cryptococcosis, extrapulmonary Microscopy (histology or cytology), culture, or detection of antigen in a specimen obtained affected tissues or a fluid from those tissues. Cryptosporidiosis, more than 1 month's duration Microscopy (histology or cytology), culture, or detection of antigen in a specimen obtained affected tissues or a fluid from those tissues. Cytomegalovirus disease, other than liver, spleen, or nodes Microscopy (histology or cytology), culture, or detection of antigen in a specimen obtained affected tissues or a fluid from those tissues. Cytomegalovirus retinitis with loss of vision Definitive diagnosis As for cytomegalovirus disease, other than liver, spleen, or lymph nodes.

Clinical Description And Epidemiology

Among immunocompetent patients, resistance to ACV is rare, with a prevalence below 1 6 and most often detected in the course of recurrent genital herpes. In this situation, the observed prevalence ranged from 3.5 7 to 8.6 , 8 and in most cases, clinical course was unchanged. Prevalence of ACV resistance among immunocompromised patients is about 5 according to several published reports recently reviewed by Bacon et al. 6 But this global incidence has to be specified according to the type of immunosuppression as resistance may be detected in up to 25 of allogeneic bone marrow transplant patients presenting with an HSV infection. 9

Management Of Resistant Infections

The first way to manage ACV-resistant HSV infection is, when possible, to decrease immunosuppressive treat-ments. 15 An increase of antiviral dose should also be Several alternative antiviral drugs are also available. Penciclovir is a nucleoside analogue of guanosine and is very similar to ACV. Indeed, most ACV-resistant HSV isolates are also resistant to penciclovir. Foscarnet, a pyrophosphate analogue, and cidofovir, a nucleotide analogue of cytidine, act directly on viral DNA polymerase without previous activation by viral TK and both these molecules are active on viruses resistant to ACV because of a mutation in the TK gene. 17,18 Acyclovir-resistant management strategies usually recommend the use of Cross-resistance between ACV and foscarnet has been documented in immunocompromised patients. 19-21 Nevertheless, foscarnet-resistant strains sensitive to ACV have also been reported. 21 Acyclovir-resistant strains, cross resistant or not to foscarnet, have always been shown to be...

Genetic Characterization

Herpes simplex virus TK is involved in 95 of HSV resistance to ACV. It is a 376-amino acid protein, encoded by a gene of 1128 bp (UL 23). It exhibits an ATP binding site (amino acid 51 to 63) and a nucleoside binding site (amino acid 168 to 176) and six regions conserved among herpesviridae TK (amino acid 50 to 66, 79 to 91,162 to 178, 212 to 226 and 281 to 292). Figure 1 presents the localization of mutations reported in ACV-sensitive and ACV-resistant HSV clinical isolates, in relation to the localization of active and conserved sites of the enzyme. These data were obtained by genetic characterization of about 70 ACV-resistant HSV isolates and 30 ACV-sensitive HSV isolates. 24,25 These studies revealed a large degree of polymorphism in the HSV TK gene. The mutations unrelated to resistance are located throughout the gene but conserved regions among herpesviridae TK Q GC homopolymer repeats b.s. binding site Ns nucleoside conserved regions among herpesviridae TK Q GC homopolymer...

Classification and Properties of the Virus

MDV and HVT are typical herpesviruses, in the family Herpesviridae, subfamily Alphaherpesvirinae, genus Marek's disease-like viruses. The nucleocapsid measures 85-100 nm and has 162 hollow capsomeres. Enveloped particles measure up to 400 nm. The nucleoid has a spherical to toroidal structure. Although originally placed with the gammaherpes-viruses because of their lymphotropism, molecular studies show that MDV and HVT are more closely related to the alphaherpesviruses, such as herpes simplex virus.

Properties of Virus Proteins

More than 40 virus-specific polypeptides, many glycosylated, have been isolated from MDV- or HVT-infected cells. The A antigen detected by gel immunoprecipitation is a secreted cell-surface antigen of unknown function. Its gene is homologous to the gC gene of herpes simplex virus. The B antigen detected by immunoprecipitation stimulates virus-neutralizing antibodies and consists of three polypeptides. Its gene is homologous to the gB gene of herpes simplex virus. A C antigen has also been identified by immunoprecipation its gene has not yet been identified.

Background Information

Interest centered on the viral proteins synthesized during the infection and the DNA content changes (both cellular and viral) that occurred as infection proceeds. Cells for these studies were derived from monolayer cell cultures of infected, mock-infected, and transformed populations. The protocol has been used for many other viral agents, such as polyoma virus, cytomegalovirus (CMV), and human immunodeficiency virus (HIV), as well as any viral protein to which a monoclonal or polyclonal antibody is available (Elmendorf et al., 1988 McSharry et al., 1990). Both the lytic and the transforming cell models of SV40 infection have been studied with this technique.

Infection and Replication

Many MHV-68 genes have been assigned functions based on their orthology to genes of other herpesviruses whose roles are known. The use of signature-tagged transposon mutagenesis has resulted in the identification of a number of MHV-68 genes that are essential for the replication process, as well as several genes that are not essential but significantly enhance viral replication. So far, 41 genes have been shown to be essential for viral replication, of which 17 are essential for replication in all herpesviruses, including MHV-68 ORF6 (encoding the single-stranded DNA-binding protein, ssDNA bp), ORF8 (glycoprotein B, gB), ORF9 (DNA polymerase, DNA pol), ORF22 (glycoprotein H, gH), and ORF64 (large tegument protein). Some essential genes have homologs only within the gammaherpesviruses, including ORF45, which corresponds to the KSHV IRF7-binding protein. MHV-68 transcription occurs in a temporal fashion and is detected from 3 h post infection (p.i.) in vitro. The replication genes ORF6...

Crossing From Slood To Brain

Cell-to-cell spread may also involve axoplasmic transport causing infection of functionally linked cells for example, in poliovirus infections the virus is rapidly spread through the motor system. Some viruses infect only neuronal populations such as rabies, polioviruses, and the arthropod-borne viruses, and some only infect selective neuron populations. Other viruses, such as herpes simplex virus, appear to infect neurons and glial populations with little selectivity.

Harvesting Bone Marrow

The GFP transgenic mouse used as the donor strain was obtained from Andras Nagy at Mount Sinai in Toronto, Canada, described in ref. 11. The strain carries a GFP transgene driven by a chicken beta-actin promoter and cytomegalovirus (CMV) intermediate early enhancer. All cell types within this animal express GFP (see Note 1).

Physical Properties and Epidemiology

Each of the nonhuman primate alphaherpesviruses has features in common with its human counterparts with respect to host range, replication kinetics, transmission, tissue tropism, pathogenecity, histopathology, and induced immune responses. The exception is B virus, which can infect humans, often resulting in a fatal zoonotic infection when left untreated. Each virus is predominantly found in one type of monkey, and recent experience indicates that antibody cross-reactivity with isolates from other species should be evaluated carefully in order to avoid deducing wrongly that a virus is endemic in multiple monkey types. As mentioned above, this is particularly apparent in the case of SA8 and HVP-2, but also features in case studies of alphaherpesviruses from Asian and African monkeys, as well as greater and lesser apes. Although apes are likely to have co-evolved with their own respective alphaherpesviruses, investigators have not yet found herpesviruses other than HSV-1 and HSV-2 in...

Virus Replication

Nonhuman primate alphaherpesviruses appear to follow the same pattern of biosynthetic activities leading to virus replication and assembly as do their human counterparts, with some exceptions noted. The nonhuman primate sim-plexviruses replicate in a manner similar to HSV, with a replication cycle of approximately 18 h. Cytopathic effects in cultured cells are also similar, with the exceptions of B virus and mangabey herpesvirus, which induce cell fusion between infected cells and also with neighboring uninfected cells. Figure 1 shows representative cytopathic effects of B virus versus other alphaher-pesviruses in nonhuman primate cells. SVVreplicates with kinetics similar to VZV over an interval of 48-72 h in cell culture and, like VZV, remains mostly cell associated. Following adsorption of a nonhuman primate alpha-herpesvirus to a susceptible cell, de-enveloped capsids are released into the cytoplasm and proceed to the nuclear membrane by mechanisms that are poorly understood, but...

Immune Response to Infection

Nonhuman primates infected by their respective alpha-herpesviruses induce humoral antibodies generally within 7-14 days following the onset of acute replication. Antibody titers, however, are not apparent in all animals within this period. Titers can also wax and wane depending on the intervals between reactivated infections. Nonetheless, intermittent virus shedding makes reliance on virus isolation or polymerase chain reaction (PCR) impractical thus, detection of antibodies is used as the current indicator of whether an animal is infected. Antibodies induced in Old and New World monkeys are

Viruses Affecting the Heart

Commonly e.g. enteroviruses, human immunodeficiency virus (HIV) and, if acquired congenitally, rubella whereas others are uncommon e.g. varicel-la-zoster, cytomegalovirus (CMV) and hepatitis B . Many of these viruses involve the heart as part of a clinically obvious generalized infection (e.g. varicella, mumps and rabies) whereas in others, cardiac disease is the primary presenting clinical feature. The more common causes of viral heart disease are discussed below, but some of those occurring less commonly are listed in Table 1.

Growth Transformation of Human T Cells by Rhadinoviruses

Transformation by HVS C488 has, in many cases, been the only way to cultivate and amplify T cells from patients with primary human immune deficiencies, including genetic T-cell defects involving the CD3g chain, IL-2Rg chain, CD95 Fas, IL-12R, major histocompatibility complex class II, Wiskott-Aldrich syndrome, or CD18 LFA-1. HVS-transformed human CD4+ T cells provide a productive system for T-lymphotropic viruses such as human herpesvirus 6 and human immunodeficiency virus (HIV) types 1 and 2, including primary clinical and macrophage-tropic HIV isolates.

Modeling Virus Particles with CryoEM Density Map Constraints

It is not uncommon for components of a virus particle to be crystallized and structurally determined while only a low- or medium-resolution cryoEM map of the entire virus particle is available. In these cases, a pseudo-atomic model of the virus particle can often be built by docking the crystal structures of the solved components into the cryoEM map. The docking can be done visually or quantitatively using a fitting program. Examples of this are provided by adenovirus and herpesvirus. In neither case has the intact capsid been crystallized, but inserting the crystal structures of the adenovirus hexon and penton base proteins, or a domain of HSV-1 major capsid protein

Conservation of Structural Motifs among Viruses

Resolution can provide sufficient information on the pattern of secondary structure elements and thus of the protein folds. Figure 10 shows a structural comparison of the capsid proteins of the eukaryote-infecting herpes-virus (Herpesviridae) and the prokaryote-infecting tailed DNA bacteriophages (Caudovirales). Although these proteins have no detectable sequence homology, it is clear from the similar spatial distributions ofsecondary structural elements that they share a characteristic fold. CryoEM-derived structural data have also revealed conserved features in the unique portal vertices of the two virus types, including a characteristic subunit arrangement and a similar location within the capsid shell (Figure 9(a)). These observations have led to the conclusion that these very distinct, extant viruses must have arisen from the same primordial progenitors.

Rhadinoviruses from Retroperitoneal Fibrosis

In an approach using a degenerate PCR technique, Rose and co-workers identified fragments of a herpesvirus DNA polymerase gene in tissue specimens from retroperitoneal fibromatosis (RF) from macaque species, M. nemestrina (six cases) and M. mulatta (one case). RF is a rare disease occurring in immunesuppressed macaques that consists of aggressively proliferating fibrous tissue with a high degree of vascularization thus, it somewhat resembles KS. Earlier transmission studies indicated that an infectious agent may be involved in RF pathogenesis. Sequence comparisons indicate that the DNA polymerase and adjacent genes of these two potentially novel rhadinoviruses, tentatively termed RFHVMm and RFHVMn, are related more closely to KSHV than RRV. Attempts to isolate the viruses on cultured cells have so far been unsuccessful. The possible coexistence of two different rhadinoviruses in the same host animal is also indicated, since in one study all RF-diseased macaques harbored RRV DNA (and...

Lymphocryptoviruses of Old and New World Primates

Gammaherpesviruses closely related to EBV have been recognized in several species of Old World primates from the mid-1970s. The genome of rhesus lymphocryptovirus (abbreviated to rhesus LCV species Cercopithecine herpesvi-rus 15) has been sequenced. Until recently, the paradigm was that the lymphocryptoviruses are restricted to Old World primates, including humans. However, a virus related to EBV was isolated from common marmosets, both from healthy animals and animals with spontaneous B-cell lymphomas. Related lymphocryptoviruses have also been detected in several other New World primate species (Table 1). The new lymphocryptovirus (marmoset LCV species Callitrichine herpesvirus 3) has an EBV-like genome structure, and determination of the genome sequence has shown that several Old World primate lymphocrypto-virus-specific genes are absent. Specifically, homologs of EBV BCRF1 vIL10, BARF1 CSF-1R, BARF0, the EBERs, and several other genes of unknown function have not been detected,...

Induction of Retinal Ischemia

VEGF is administered directly into the vitreous using a 36-gage needle and Hamilton syringe (see Note 8). Either purified (40 g kg) VEGF protein or AAV-VEGF virus (2 x 108 viral particles), where the CMV promotor drives expression of VEGF in an adeno-associated virus (AAV) vector, can be used. VEGF is an endothelial cell-specific mito-gen that is transcriptionally regulated by the cytomegalovirus promoter enhancer when packaged in AAV. AAV mediates the long-term expression in nondividing cells, which allows for stable expression and constant amounts of VEGF to reach the area of ischemia to promote neovascularization (Fig. 3 ref. 12).

Replication Strategies

The lytic cycle pathway of gene expression for primate CMVs follows the typical herpesvirus cascade of IE mRNAs and proteins followed by activation of delayed-early (DE) then late (L) class genes, with synthesis of viral DNA. In cell culture, fully permissive host cell types for HCMV are restricted almost exclusively to diploid cells, including human fibroblasts, vascular endothelial cells (and the U373 astrocytoma cell line), smooth muscle cells, and differentiated macrophages. Fresh clinical HCMV isolates usually need to be adapted for efficient growth in fibroblasts by multiple rounds ofpassaging, which is accompanied by selection of inactivating point mutations (or deletions) in certain 'cell tropism' genes and a loss of ability to grow in endothelial cells or macrophages.

Effects Of Viral Infection On Glial Precursor Cell Function

One of the most common inducers of an inflammatory response in the CNS is infection with one or more of the human herpesviruses. An increasingly varied and complex array of inflammatory and other mechanisms of viral pathogenesis have been recently described, many of which involve the production of chemokines, predominantly by infected microglia and astrocytes. For example, both TNF-a and IFN-y, discussed earlier for their potent effects in the oligodendrocyte lineage, as well as IL-6 are produced in the mouse CNS after corneal inoculation with HSV-1 105 . Similarly, infection of lymphocytes with the related human herpesvirus 6 (HHV-6) has been shown to induce expression of a variety of TNF-associated factors and receptors as well as the IFN-y activating factor, IL-18 106 . Other studies have demonstrated production of these same cytokines together with IL-1P and the P-chemokines RANTES, MIP-la, MIP-ip, and MCP-1 in microglia or astrocytes infected with either human cytomegalovirus or...

Microarray Design for Viral Detection

After satisfying the basic design requirements, more sophisticated considerations may also contribute to choice of viral sequence for representation on a microarray. For example, to enhance detection of latent herpesviruses, it may be advantageous to overrepresent sequences specific for genes specific for latent phase expression, rather than those involved in lytic processes. In this case, it is assumed that the RNA rather than DNA will be analyzed, which highlights the importance of sample processing and amplification considerations.

Latent and slow persistent viral infections

After an infection has passed, a virus may sometimes remain in the body for long periods, causing no harm. It may be reactivated, however, by stress or some change in the individual's health, and initiate a disease state. Well known examples of latent viral infections are cold sores and shingles, both caused by members of the herpesvirus family. A virus of this sort will remain with an individual throughout their lifetime.

Challenges for the Future

See also Adenoviruses (Adenovlridae) Animal viruses General features Malignant transformation and oncology Molecular biology Cytomegaloviruses (Herpesviridae) Animal cytomegaloviruses General features (human) Molecular biology (human) Murine cytomegaloviruses Ep-stein-Barr virus (Herpesviridae) General features Molecular biology Herpes simplex viruses (Herpesviridae) General features Molecular biology Human immunodeficiency viruses (Retro-viridae) Anti-retroviral agents General features Molecular biology Immune response Cell

Detection of Viral Antigens

Antigen detection methods are especially recommended in the case of virus reactivation, for example, for herpes simplex and varicella zoster virus diagnosis where the sero-logical response can be very weak. Antigen detection assays are also widely used in respiratory tract infections like influenza and respiratory syncytial virus infections. A simple test for the demonstration of rotavirus and adenovirus antigens in children with gastroenteritis is also available.

Current Vectors 1321 Vp22

The protein VP22 is found in the amorphous tegument layer of herpes simplex virus 1 (HSV-1).24 A relatively small (36 kDa), highly basic protein, it has been shown to undergo covalent modification (phosphorylation25 and nucleotidylation26) and interacts with cellular components such as microtubules and chromatin.16,27-29 Although the exact function of VP22 in the HSV-1 assembly and infection pathways is not yet known, a perhaps related function of the protein has been demonstrated, which has sparked considerable interest VP22 demonstrates both nonclassical import and export activity. As originally demonstrated by Elliott and colleagues, the protein enters and exits cells in an energy-independent manner, although it lacks either a known N-terminal secretion signal or a nuclear localization sequence (NLS).16 This latter absence is surprising because the protein is also found in the nucleus of the cell after import. (It is possible that the highly basic C-terminal region of the protein...

Steps to Increase Safety of Blood Derived Clotting Factor Products

Screening plasma for HIV, hepatitis (A, B, and C), parvovirus B19, syphillis, and cytomegalovirus is now a routine and standard practice. Traditionally, this was performed using enzyme-linked immunosorbent assay (ELISA) testing, an extremely sensitive method for detecting pathogens 42 . More rapid and sensitive nucleic acid amplification testing (NAT) has been introduced in most North American and European countries since the late 1990s. NAT offers an increased margin of safety for clotting factor concentrates 41 , in that it enables detection of hepatitis A and parvovirus, both of which are relatively recalcitrant to many viral inactivation technologies (see below).

William A Carlezon Jr and Rachael L Neve 1 Introduction

The use of any viral vector system for gene transfer studies in brain depends on the dynamic interaction of a number of factors, ranging from the hypothesis that is being tested, the brain region targeted for study, the viral backbone that is used as the vector, the titer of the vector, and the volume of the vector that is injected into the brain. Unfortunately, there is little information in the literature about how one, once in possession of a vector of interest, would embark on a gene transfer study. This chapter describes some of the protocols that we developed for viral-mediated gene transfer studies in which we used herpes

Concept of DNA Vaccines

The major reason for continued interest in DNA-based vaccines is their simplicity in concept, ease of production, potential to develop a broad range of immune responses, as well as their perceived safety and ability to induce immunity in neonates in the absence or presence of maternal antibodies. With regards to simplicity, a DNA vaccine is comprised of a plasmid containing various regulatory elements to ensure efficient production of the plasmid in bacterial systems, such as an origin of replication and a selectable marker as well as an expression cassette containing the gene of interest under a eukaryotic promoter usually human cytomegalovirus for efficient expression of the gene inserted into mammalian cells. Since the general features of a plasmid are identical for all vaccines, the single platform makes DNA vaccines very attractive from the prospective of manufacturing. Thus,

Attractiveness of DNABased Vaccines

One desirable feature of any vaccine is the ability to protect individuals against a variety of disease agents following single administration of a vaccine. Thus, multi-component vaccines are gaining popularity, not only because of the breadth of protection they induce, but also because of improved compliance since individuals do not need to return for numerous vaccinations. One limitation of combining multiple conventional vaccines is the possibility of interference between various components in the vaccine. With DNA vaccines this is also a possibility, but it should be possible to identify which component is interfering in induction of immunity. For example, in the study of a vaccine containing nine different plasmids encoding nine different malarial antigens, reduced immune responses to various components were observed compared to responses induced by individual plasmids. Similarly, we observed interference between plasmids encoding the genes for bovine herpes-virus-1 gD,...

Neonatal Immunization

Induce immunity in neonates in the presence or absence of maternal antibodies makes this approach to vaccination extremely attractive, especially for diseases such as herpes simplex virus-2, human immunodeficiency virus (HIV), hepatitis B, group B strep, and chlamydia which often infect children during birth or shortly thereafter.

Virus Propagation

Avipoxviruses replicate only in avian cells replication in mammalian cells is abortive and no infectious progeny are produced. Some vaccine strains of FWPV, such as the Cyanamid Webster FPV-M vaccine, even display a preference for chick embryo skin cells (CESs) over chick embryo fibroblast cells (CEFs). FWPV FP9 has been effectively adapted to CEFs but it displays a distinct preference for primary as opposed to secondary CEFs. Plaques on CEFs are not lytic, but the cytopathic effects manifest as changes in cell morphology, resulting in areas of altered refractive index with the plaques best viewed by dark field illumination. FWPV fails to plaque and replicates poorly in the recently derived chicken fibroblast cell line, DF-1. Replication is similarly poor in the chemically transformed cell line OU-2. It can be plaqued and replicated quite efficiently in quail cell lines, such as QT-35, but the presence in these cells ofviable endogenous Marek's disease virus (a herpesvirus) means that...