Serological and genetic characterization of bovine rotaviruses in Thailand by ELISA and RNA-RNA hybridization: detection of numerous non-serotype 6 strains.

A total of 62 fecal specimens positive for rotavirus were collected from diarrheic cows in Thailand in 1988 and 1989. The antigenic properties of rotaviruses in stool were examined by enzyme-liked immunosorbent assays using specific monoclonal antibodies directed at VP4, VP6 or VP7: all the bovine rotavirus strains were determined as subgroup I; none of the strains were reactive with serotype 6-specific monoclonal antibody; and different reactivities of the bovine strains with two anti-VP4 monoclonal antibodies were observed. Polyacrylamide gel electrophoresis of viral RNA exhibited three different RNA electropherotypes. In RNA-RNA hybridization experiments using cell culture-adapted three strains as well as a reference bovine strain (NCDV), RNA from the Thai bovine strains showed very low homology to that from NCDV; only three or four RNA segments were hybridized between the RNAs from Thai samples and NCDV. These results suggested that bovine rotaviruses isolated in Thailand are serologically and genetically distinct from a reference serotype 6 bovine strain, NCDV.