Journal of General Virology (1991), 72, 2929-2937. Printed in Great Britain 2929 Molecular and antigenic analyses of serotypes 8 and 10 of bovine rotaviruses in Thailand Koki Taniguchi, 1. Tomoko Urasawa, 1 Yaowapa Pongsuwanna, 2 Maliwan Choonthanom, 3 Chuinrudee Jayavasu 2 and Shozo Urasawa ~ 1Department of Hygiene, Sapporo Medical College, South-l, West-17, Chuo-Ku, Sapporo 060, Japan, 2Virus Research Institute, National Institute of Health, Nonthaburi and 3Faculty of Veterinary Medicine, Kasetsart University, Bangkok, Thailand Antigenic and genomic properties of non-serotype 6 bovine rotaviruses isolated in Thailand and Japan were studied by cross-neutralization tests, nucleotide se- quence 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 ex- periments, 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 genetic- relatedness to strain 69M of serotype 8, and, to a lesser extent, to serotype 2 human rotavirus strains. Introduction Group A rotaviruses, which are the most common cause of diarrhoea in the young of a number of mammalian and avian species, include 12 serotypes defined by cross- neutralization tests (Estes & Cohen, 1989; Kapikian & Chanock, 1990). Serotypes 1, 2, 9 and 12 have been detected almost exclusively in humans so far (Hoshino et al., 1984; Clarke et al., 1987; Urasawa et al., 1990), except that porcine strains of serotype 1 or 2 specificity have been isolated recently (Bellinzoni et al., 1990). Serotype 3 strains have a broad host range and are found in humans, monkeys, horses, pigs, dogs, cats, rabbits and mice (Nishikawa et al., 1989). Serotype 4 is the cause of diarrhoea in humans and pigs, and serotype 5 strains have been isolated from horses and pigs (Hoshino et al., 1984). Serotypes 7 and 11 are restricted to avian and porcine species, respectively (Hoshino et al., 1984; Ruiz et al., 1988). Serotype 8 strains have been isolated from humans (Matsuno et al., 1985; Albert et al., 1987), and they have been detected recently in calves (Snodgrass et The nucleotidesequencedata reported in this paper appear in the DDBJ, EMBLand GenBankNucleotideSequenceDatabases under the accessionnumbers D01054 (strain A5), D01055 (strain A44) and D01056 (strain KK3). al., 1990). Most bovine rotaviruses (BRV) including reference strains NCDV and UK belong to serotype 6, whereas several BRV strains represented by strains B223, KK3 and V1005 were recently assigned to serotype 10 as the second serotype of BRV (Br/issow et al., 1990; Snodgrass et al., 1990). Group A rotaviruses with genomes composed of 11 dsRNA segments, have two neutralization proteins, VP4 and VP7 (Hoshino et al., 1985; Offit & Blavat, 1986). The serotype specificity is defined largely by VP7, which is encoded by RNA segment 7, 8 or 9 depending on the strain (Estes & Cohen, 1989; Kapikian & Chanock, 1990). Precise analysis of the serotype-specific VP7 antigenic structure and worldwide epidemiological surveys on the serotype distribution of rotaviruses will provide information necessary for the development of effective vaccines. In our previous study (Pongsuwanna et al., 1990), 23 Thai BRV strains, all which were of the subgroup I and long RNA migration pattern, did not react with a serotype 6-specific monoclonal antibody suggesting that they belong to other serotypes and that non-serotype 6 BRVs are frequent in Thailand. The nucleotide sequence of the VP7 gene of strain 61A was determined (Taniguchi et al., 1990a) and found to be similar to that 0001-0457 © 1991 SGM