VP7, VP4, and NSP4 genes of species a rotaviruses isolated from sewage in Nigeria, 2014/2015: partial sequence characterization and biophysical analysis of NSP4 (enterotoxin).

Species A rotavirus are an important cause of childhood gastroenteritis, and the main contributor to its pathogenicity is the enterotoxin (NSP4) protein. Some biophysical properties of partial NSP4 genes of RVAs isolated from sewage in Nigeria during 2014/2015 were investigated. Samples were typed by RT-PCR and Sanger sequencing of partial VP4, VP7 and NSP4 genes. Phylogeny identified lineages within genotypes, predicted glycosylation sites; hydrophobicity profiles and amino acid alignments were employed to determine some biophysical properties of the NSP4 protein. The VP7 sequences of our isolates were the most diversified, the majority of the isolates carried NSP4 genes of the E1 genotype. Genotype specific variations both in hydrophobicity and potential glycosylation were identified, mutations were highest within the H3 hydrophobic domain and VP4 binding domain. The study of RVA NSP4 genes from non-clinical samples revealed that there were structural consistencies with those of reference genes.