%0 Journal Article %A Burroughs, J. N. %A Brown, F. %T Physico-chemical Evidence for the Re-classification of the Caliciviruses %D 1974 %J Journal of General Virology, %V 22 %N 2 %P 281-286 %@ 1465-2099 %R https://doi.org/10.1099/0022-1317-22-2-281 %I Microbiology Society, %X SUMMARY The caliciviruses (feline picornavirus and vesicular exanthema virus) have a diam. of 35 to 40 nm and possess a distinctive morphology which clearly distinguishes them from the other members of the family Picornaviridae. They also differ in having an E 260/280 ratio of about 1.52 compared with 1.65 to 1.70 for the picornaviruses. More significantly, they are unique among the mammalian viruses in containing only one major polypeptide, mol. wt. about 65 × 103. Feline picornavirus and vesicular exanthema virus differ from each other in their behaviour in caesium chloride gradients and in the base composition of their RNAs. Our evidence suggests that the two viruses are not typical picornaviruses but are in fact distinct members of a new virus family, the Caliciviridae. %U https://www.microbiologyresearch.org/content/journal/jgv/10.1099/0022-1317-22-2-281