Analysis of the serologic relationship among San Miguel sea lion virus and vesicular exanthema of swine virus isolates. Application of the western blot assay for detection of antibodies in swine sera to these virus types.

Caliciviruses are positive-sense single-stranded RNA viruses with a single capsid protein. The serotypes of the marine mammal calicivirus, San Miguel sea lion virus (SMSV), are antigenically related to vesicular exanthema of swine virus (VESV) and are potentially hazardous to swine. Western blot assays using purified SMSV serotypes 1 and 4 were used to further examine the serologic relationship among SMSV and VESV isolates. With the exception of SMSV 8 and SMSV 12, rabbit polyclonal antisera generated against all the available SMSV and VESV isolates reacted positively, as assessed by western blot, with purified capsid protein from SMSV 1 and SMSV 4. Consequently, the SMSV 8 and SMSV 12 virus isolates may not be members of the SMSV/VESV calicivirus group. Using antisera from pigs experimentally inoculated with SMSV and VESV as positive controls, a western blot assay for these virus types was utilized to check for the presence of antibodies to calciviruses in swine sera. Sera from colostrum-deprived gnotobiotic pigs were used as a negative control in all experiments. Examination of sera from domestic and feral swine collected in Iowa, California, and Florida was completed using this technique. The presence of antibodies to these virus types was not detected in any of the porcine sera tested.