A major difference in the strategy of the calici- and picornaviruses and its significance in classification.

Pig kidney (1BRS-2) cells infected with vesicular exanthema virus (VEV), a calicivirus, did not contain any large precursor polypeptides similar to those found when they were infected with foot-and-mouth disease virus (FMDV). The largest induced protein found in the VEV-infected cells had a molecular weight identical with that of the virus structural polypeptide. This difference in strategy between VEV and FMDV, taken in conjunction with the morphological and structural differences described previously, provides strong evidence that the caliciviruses should not be included in the family Picornaviridae.