Summary auto-generated
This study identified three distinct alleles of rotavirus NSP4, a nonstructural glycoprotein, by analyzing NSP4 gene sequences from 22 rotavirus strains across six host species. The three alleles—designated Wa, KUN, and AU-1—show genetic distances of approximately 18% between them but only 5% variation within each allele, suggesting they diverged simultaneously during evolution. Phylogenetic analysis confirmed these three major lineages using neighbor-joining methods. Notably, NSP4 functions as both an intracellular receptor for viral morphogenesis and a viral enterotoxin that triggers diarrhea through calcium-mediated ion transport disruption. The amino-terminal two-thirds of NSP4 remained highly conserved across strains, particularly in domains important for viral morphogenesis. However, sequence variation increased toward the carboxy terminus, with greatest variability between amino acid residues 135-141 in the enterotoxic peptide region. Comparison of strains from asymptomatic neonates versus symptomatic children revealed no specific amino acid substitutions that correlated with disease capacity, though the conserved structural features suggest functional constraints on protein evolution.
Key findings
- Three distinct NSP4 alleles (Wa, KUN, AU-1) were identified with ~18% genetic distance between alleles but only ~5% within alleles
- NSP4 domains important for viral morphogenesis showed high sequence conservation, particularly the amino-terminal regions
- The enterotoxic peptide region (amino acids 114-135) showed minimal variation, with greatest variability between residues 135-141
- No specific amino acid substitutions in the enterotoxic peptide region correlated with symptomatic versus asymptomatic infection status
- The three NSP4 alleles likely diverged at approximately the same evolutionary time point from a common ancestor
This summary was generated automatically from the article PDF and is not part of the original publication. Refer to the PDF for the authoritative text.
Abstract
Comparison of nonstructural glycoprotein NSP4 gene sequences from 22 rotavirus strains originating from six host species and of 14 different combinations of G and P types revealed the presence of three distinct NSP4 alleles, represented by strains Wa, KUN and AU-1. Genetic distances between any of these alleles (18.0%) were significantly greater than those within each allele (5.5%) and phylogenetic analysis suggested that divergence into three distinct alleles had occurred at about the same time during evolution. While amino acid variation among strains was minimal in the amino-terminal two-thirds of the protein (aa 1-130), variability increased toward the carboxy terminus of the enterotoxic peptide region (aa 114-135) and was greatest between residues 135 and 141. Comparison of the amino acid sequences corresponding to the enterotoxic peptide region between strains isolated from asymptomatic neonates and those from children with diarrhoea failed to identify any conserved changes that correlated with the capacity of the virus to cause disease. Amino acids were relatively conserved in the domains important for viral morphogenesis.