Characterisation of rotaviruses recovered from neonates with symptomatic infection.

An unusually high number of diarrhoeal stools were obtained from neonates at different maternity units in Pretoria during late 1986 and the winter of 1987 and tested for the presence of rotavirus infection. Latex agglutination assay revealed rotavirus in 67% (93/139) of the stools from newborn babies. Gel electrophoresis of the rotavirus genome showed that a genomically stable strain of rotavirus was associated with the diarrhoeal illness in all maternity units investigated. Determination of the VP6 subgroup specificity using monoclonal antibodies demonstrated that all strains were of subgroup II. Examination of the VP4 and VP7 rotavirus genes, which encode for the outer capsid neutralisation proteins of the virus, was conducted by hybridisation analysis using probes directed at the divergent regions of the two genes. These results showed the presence of a VP7 serotype G4 rotavirus strain with a P6 VP4 genotype-the putative 'attenuated' VP4 gene allele-circulating in all maternity units studied.