Systematic Veterinary Virology

MORPHOLOGY

• The virions are non-enveloped and hence is not ether sensitive. The virion has icosahedral symmetry. The virion comprises of four polypeptides, VP1, 2, 3 and 4 and all these proteins are derived from cleavage of a single polypeptide VP0.
• The virion  contains one molecule of linear positive-sense single stranded RNA. The Genomic RNA is infectious. Both ends of the genome are modified, the 5' end by a covalently attached small, basic protein VPg and the 3' end by polyadenylation. 
• The genome contains approximately 7000-8500 nucleotides. 2,500nm and it is tightly packed into the capsid.