Characterisation of a "European-like" serotype G8 human rotavirus isolated in Australia

An atypical human rotavirus strain, DG8, was isolated from a 13-month-old child hospitalised with acute gastro-enteritis in Australia. The virus could not be serotyped by enzyme immunoassay (EIA) using standard reagents specific for common Group A human rotavirus G serotypes. The deduced amino acid sequence of the outer capsid glycoprotein, VP7, indicated that this strain belonged to the uncommon human serotype G8. This was confirmed by EIA incorporating a G8-specific neutralising monoclonal antibody (NMAb). The VP4 genotype of DG8 was determined as P[14], equivalent to P serotype P3B, by sequence analysis and confirmed by EIA incorporating a P3B-specific NMAb. Electrophoretic analysis of DG8 genomic dsRNA indicated that the virus exhibited a "long" electropherotype. Northern hybridisation analysis (using a whole-genome probe derived from DG8) indicated that DG8 shared overall homology with the European serotype G8 strain, HAL1166 (11 of 11 genes). In contrast, only 9 of 11 genes of DG8 hybridised with the Asian serotype G8 strain, B37, and with the bovine G8 strain, A5. Hence, DG8 displayed features reminiscent of the human serotype G8 rotaviruses isolated in Europe in the mid-1980s rather than the geographically local G8 Asian strains isolated a decade earlier. It is possible that DG8 arose through reassortment between human and bovine rotaviruses.