Antigenic relationships among some bovine rotaviruses: serum neutralization and cross-protection in gnotobiotic calves

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Abstract
A method was further developed to screen non-tissue-culture-adapted bovine rotaviruses for serotype, using a neutralization test with infectious fecal rotavirus. One of those rotaviruses (B223) which was not blocked by antiserum to the neonatal calf diarrhea virus (NCDV) serotype was then adapted to cell culture in the presence of the antiserum for .gtoreq. 2 passages, and hyperimmune antiserum to this isolate had a 60-fold-higher homologous neutralization titer than with the NCDV serotype rotavirus. Isolates (73) were serotyped and 8 (11%) were not of the NCDV serotype (bovine rotarvirus serotype I). Of thes 8, 5 belonged to the new bovine rotavirus serotype II and 3 were not typed, indicating the existence of .gtoreq. 1 further serotypes. Cross-protection studies in gnotobiotic calves showed that cross-protection only occurred between rotaviruses of the same serotype, and even a minor serotype difference was sufficient for the claves to show a lack of cross-protection. The serotypes (I and II and the 3 untyped isolates) also showed differences in the rate of migration in polyacrylamide gel electrophoresis of some of their RNA segments (no. 4, 6, 7, 8, 9, 10), indicating that they were of different electropherotypes.