Further characterisation of human rotaviruses isolated from asymptomatically infected neonates in South Africa.

Stool specimens were collected from healthy neonates at Ga-Rankuwa Hospital in the winters of 1984 and 1986 and tested for the presence of rotavirus infection. Asymptomatic excretion was found to occur in 25% of the newborn babies analysed. Gel electrophoresis of the rotavirus RNA genome revealed that a genomically stable strain of rotavirus was endemic in the ward at the time intervals examined. Hybridisation analysis of the VP4 and VP7 rotavirus genes, which encode the outer capsid neutralization proteins of the virus, was conducted. These results showed the presence of a serotype 4 rotavirus strain with an M37-like VP4 gene allele, which remained conserved in the nursery over the time period examined. Partial nucleotide sequences were obtained for a variable region of the VP7 gene and for the hyperdivergent region of the VP4 gene from 8 of these viruses and showed that remarkable conservation of these regions in the genes of the viruses occurred over time.