Group A
human rotaviruses (HuRVA) are causative agents of acute
gastroenteritis. Six
viral structural proteins (VPs) and six nonstructural
proteins (NSPs) are produced in RV-infected
cells. NSP4 is a diarrhoea-inducing viral
enterotoxin and NSP4
gene analysis revealed at least 15 (E1-E15)
genotypes. This study analysed the NSP4
genetic diversity of HuRVA G2P[4]
strains collected in the
state of São Paulo (SP) from 1994 and 2006-2010 using
reverse transcription-
polymerase chain reaction, sequencing and
phylogenetic analysis. Forty (97.6%) G2P[4]
strains displayed
genotype E2; one
strain (2.4%) displayed
genotype E1. These results are consistent with the proposed linkage between VP4/VP7 (G2P[4]) and the NSP4 (E2)
genotype of HuRVA. NSP4
phylogenetic analysis showed distinct clusters, with grouping of most
strains by their
genotype and collection year, and most
strains from SP were clustered together with
strains from other Brazilian states. A deduced
amino acid sequence alignment for E2 showed many variations in the C-terminal region, including the VP4-binding domain. Considering the
ability of NSP4 to generate host
immunity,
monitoring NSP4 variations, along with those in the VP4 or VP7
protein, is important for evaluating the circulation and
pathogenesis of RV. Finally, the presence of one G2P[4]E1
strain reinforces the idea that new
genotype combinations emerge through reassortment and independent segregation.