Calf fecal rotavirus strains were serotyped in enzyme-linked immunosorbent assays, using monoclonal antibodies to the VP7s of serotypes 1, 2, 3, 5, and 6 and to the VP4 of B223 (designated serotype 10). Sixty-six percent of 162 samples were typed as serotype 6, and 7% were serotyped as serotype 10. Most of the untyped strains did not react with a monoclonal antibody directed to a common VP7 epitope, indicating insufficient virus present in the samples. However, seven untyped samples that did react with this antibody were adapted to culture and typed, and six of these also proved to belong to serotype 6 or 10. Two of these viruses belonged to a monotype within serotype 6 that did not react with the serotype 6 monoclonal antibody. The seventh isolate reacted in cross-neutralization tests with serotype 8 viruses. Bovine rotaviruses from the United Kingdom, Federal Republic of Germany, and Japan that had been shown previously to be distinct from serotype 6 were compared in neutralization tests with B223 from the United States. These viruses proved to be a closely reacting group distinct from all other rotavirus serotypes, justifying the establishment of serotype 10 as the second major type of bovine rotavirus.

A group A rotavirusdesignated L338 was isolated from the faeces of a diarrhoeic foal and was compared to 11 standard G serotype strains of group A rotaviruses by cross-neutralization. It was clearly distinct from serotypes G1 to Gll and thus representative of a novel rotavirus G serotype tentatively designated G13. The nucleic acid sequence of the virion protein 7 (VP7) coding region was determined and the deduced amino acid sequence compared to published sequences. Within VP7 regions A and B, L338 was clearly distinct from serotypes G1 to G12 (excluding G7 which has not been sequenced), but region C was very similar to those of G3 and G8. This further questions the significance of region C in determining serotype specificity of at least three distinct rotavirus G serotypes.

Equine rotavirus F123 was shown to be prototypic of a novel G serotype, provisionally G14, by crossneutralization and VP7 sequence determination. Although distinct, there are as few as six differing amino acid residues (92, 94, 96, 146, 147, and 221) in the VP7 antigenic regions of F123 and G3 rotaviruses.

A series of five reassortant viruses each containing the VP4 gene of a distinct bovine rotavirus and the VP7 gene of human rotavirus strain ST3 was prepared, and antisera to these were produced in rabbits. In neutralization tests, these antisera allowed the differentiation of the five original strains (from three different VP7 or G serotypes) into three or possibly four VP4 or P serotypes. All of a further seven bovine rotavirus strains adapted to cell culture were successfully typed by these antisera. There was a degree of cross-reaction between antiserum to the fourth bovine rotavirus P serotype and the predominant human rotavirus serotype. However, antisera raised in guinea-pigs to recombinant VP4 from this serotype showed the bovine serotype to be distinct. There was no significant serological relationship between these four bovine rotavirus P serotypes and previously described P serotypes from rotaviruses isolated from man and non-bovine animals. The predominant bovine rotavirus VP7 serotypes G6 and G10 tended to have distinct P serotypes also.

Four lamb rotaviruses were characterised serologically by reactions with monoclonal antibodies and genomically by hybridisation assays and sequencing. Each was found to be distinct. Three viruses belonged to the bovine genogroup and were of subgroup I. These viruses possessed serotypes G3, G6, and G10. Their corresponding P types were P1, P11, and P14 respectively. The only previous isolation of a rotavirus with VP4 of type P14 was also from lambs. The fourth isolate was G9P8, which is the first record of a G9 rotavirus from a species other than man.