Antigenic and genomic properties of non-serotype 6 bovine rotaviruses isolated in Thailand and Japan were studied by cross-neutralization tests, nucleotide sequence determination of the VP7 gene, and RNA-RNA hybridization. Two Thai strains (61A and A44) were serologically related to a Japanese isolate KK3 which has been assigned to serotype 10. In contrast, strain A5 was found to be antigenically similar to human strain 69M with serotype 8 specificity, although strain A5 showed a one-way cross-reaction with serotype 6 strain NCDV. VP7 sequence analysis confirmed these results. High degrees of similarity in nucleotide and amino acid sequences (92-5 to 98.2% and 96.3 to 97.9%, respectively) were found among the VP7 genes of the four serotype 10 bovine strains (61A, A44, KK3 and B223). The VP7 amino acid sequence of strain A5 was similar to those of serotype 8 human strains (91-7% and 94-8% for strains B37 and 69M, respectively). In RNA-RNA hybridization experiments, a high level of overall relatedness was found among the three serotype 10 bovine strains (61 A, A44 and KK3), and strains A5 and NCDV were also moderately related to the three serotype 10 viruses. All the bovine rotaviruses tested in this study, regardless of their serotype specificity, exhibited a moderate geneticrelatedness to strain 69M of serotype 8, and, to a lesser extent, to serotype 2 human rotavirus strains.

The subgroup and serotype specificities of human, bovine, and porcine group A rotaviruses in stool specimens collected in Thailand were examined by an enzyme-linked immunosorbent assay by using subgroupand serotype-specific monoclonal antibodies. A clear yearly change was observed in the serotype distribution of human rotavirus. Between 1983 and 1984, serotype 4 was the most prevalent, while the highest frequency of serotype 2 was found between 1987 and 1988. All the bovine and porcine rotaviruses examined showed subgroup I specificities and long RNA patterns. It was of note that serotype 3 porcine rotaviruses were found at a high frequency.

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