Taxonomy

The Totiviridae is a remarkable family of fungal and protozoan viruses. These viruses have a single essential double-stranded RNA (dsRNA) and are recognizably related to each other as viewed by comparison of their RNA-dependent RNA polymerases (RDRPs). They have been discovered in at least four genera of protozoans (Leishmania, Eimeria, Giardiavirus and Trichomonas) and nine genera of fungi (Saccharomyces, Ustiiago, Helminthosporium, Gaeumannomyces, Mycogone, Yarrowia, Aspergil-

1812 TOTMRUSES (7D71MHXQAE): USTILAGO MAYDIS VIRUSES

protozoa Giardia lamblia, however, has been accomplished via electroporation with (+)-strand RNA transcribed in vitro from GLV dsRNA.

There are no known experimental host ranges for the fungal totiviruses because of the lack of suitable infectivity assays. As a consequence of their intracellular modes of transmission, the natural host ranges of totiviruses are limited to individuals within the same or closely related vegetative compatibility groups. Furthermore, mixed infections with two or more unrelated viruses are common, probably as a consequence of the ways by which fungal viruses are transmitted in nature. Dual infection of yeast with ScV-L-A and ScV-L-BC is an example of mixed infection involving totiviruses. Leishmaniaviruses have been found in L. braziliensis, L. guyanensis and L. major.

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