Genetic analysis of NSP1 genes of human rotaviruses isolated from neonates with asymptomatic infection.

The nucleotide sequences of the genomic RNA segments 5 (gene 5) encoding the non-structural protein NSP1 of rotavirus strains M37 and ST3, isolated from neonates with asymptomatic infection, were determined. The sequences were similar overall (95% identity) as were the deduced amino acid sequences of NSP1 (93%). However, the M37 and ST3 NSP1 proteins shared only 82% and 81% identity, respectively, with the corresponding protein from another strain isolated from a neonate with asymptomatic infection (I321). Differences (of between 15% and 31%) were found in comparison with NSP1 sequences of rotaviruses isolated from older children with symptomatic infection (Wa, DS1 and IGV-80-3). Using an M37 gene 5-derived probe, Northern hybridization analysis of total genomic RNA extracted from viruses isolated from older children (Wa, RV4, RV5 and P) and neonates (M37, ST3, RV3 and 1076), representatives of the most common human G and P types, further indicated that while the gene 5 alleles of strains M37, ST3 and RV3 had a high degree of identity, no significant identity between 1076 and M37 was observed. In addition, cross-hybridization between the M37 probe and RNA of strains from older children (Wa, RV4 and P) was evident. Thus, neonatal human rotavirus strains do not carry a common NSP1 gene.