Properties of Virions

Virion particles of potyviruses are long and flexuous (Fig. 1A), 680-900 nm long and 11-15 nm wide. They comprise protein (95%) and RNA (5%). Viruses belonging to other genera in the family possess particles with similar properties. Ipomovirus particles are around 900 nm long, while macluravirus ones are shorter (around 650 nm). The two bymovirus particles are about 250-300 and 500-600 nm in length.

Around 2000 subunits of a single protein (CP) compose the capsid of potyviruses. The molecular weight of each subunit ranges between 30 and 47 kDa, and they are disposed helicoidally around the nucleic acid. Variations in CP size are due mainly to

Table 1 Classification of members of the family Potyviridae into genera, with indication of the number of members, transmission vectors and number of genomic RNAs

Members?

Genus Definite Possible Transmission Genome

Potyvirus

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