GENETIC RELATEDNESS OF THE CALICIVIRUSES - SAN-MIGUEL SEA-LION AND VESICULAR EXANTHEMA OF SWINE VIRUSES CONSTITUTE A SINGLE GENOTYPE WITHINTHE CALICIVIRIDAE

The San Miguel sea lion viruses (SMSV) and vesicular exanthema of swin e viruses (VESV) are related morphologically and antigenically, but li ttle has been done to determine their genotypic relationship to each o ther and to other caliciviruses. To examine this relationship, reverse transcriptase PCRs were performed by using oligonucleotide primer set s designed to amplify portions of the 2C RNA helicase-like and RNA dep endent RNA polymerase regions with total cellular RNA purified from vi rus-infected cell cultures as a template. The 2C RNA helicase primers directed the amplification of this region from eight SMSV serotypes, f ive VESV serotypes, and four related viruses. The RNA polymerase prime r sets amplified products from all these viruses except one. Phylogene tic comparison of the caliciviruses demonstrated that SMSV, VESV, and four related viruses are closely related while being distinct from fel ine calicivirus, the human caliciviruses (small, round-structured viru ses), and rabbit hemorrhagic disease virus and that they should be cla ssified as a single genotype within the Caliciviridae.