Rotavirus serotype G3 predominates in horses.

Foal fecal group A rotavirus strains were characterized by electropherotype, serotype, and subgroup and shown to be distinctly different from rotaviruses of other mammals. Of 86 strains that were electropherotyped, 98% had similar profiles, with gene segments 3 and 4 close together and segments 7, 8, and 9 widely spaced. Of 70 strains that had sufficient detectable VP7 antigen to be serotyped by enzyme-linked immunosorbent assays (ELISAs), 63% were serotype G3 (39% were subtype G3A and 24% were subtype G3B), 4% were serotype G13, and 33% were untypeable. Serotypes G1, G2, G4, G5, G6, G9, G10, and G14 were not detected, although G5 and G14 strains have been identified among cultivable equine strains. Of 50 strains that had sufficient detectable VP6 antigen to be subgrouped by ELISAs, only 12% were able to be assigned to either subgroup I or II, with the remaining 88% belonging to neither subgroup.