Genetic Susceptibility to Norovirus GII.3 and GII.4 Infections in Chinese Pediatric Diarrheal Disease

Background: Noroviruses (NoVs) are a leading cause of viral diarrhea in young children. Secretor status has been confirmed to be linked with Norwalk virus (NoV GI.1) infection but there is limited information about whether secretor genotypes are associated with pediatric NoV epidemic strains in vivo. Methods: In this study, fecal specimens and serum samples were collected from 124 hospitalized children with acute diarrhea in Xi'an, China. TaqMan real-time reverse transcription polymerase chain reaction was used to detect NoVs in fecal samples, and NoV-positive samples were further verified using conventional reverse transcription polymerase chain reaction and sequenced. DNA was extracted from sera and TaqMan single-nucleotide polymorphism genotyping assay was applied to determine the FUT2 A385T polymorphism. Results: Only NoV GI.3 and GI.4 genotypes were found in NoV-positive samples, and NoVs were detected in 25% (15/60), 40.5% (17/42) and 9.1% (2/22) of children with homozygous secretor genotype ((SeSe385)-Se-385), heterozygous secretor genotype (Se(385)se(385)) and homozygous weak secretor genotype (se(385)se(385)), respectively. Children with secretor genotypes (SeSe385)-Se-385 and Se(385)se(385) were significantly (P < 0.05) more susceptible to combined NoV GII.3 and GII.4 infections than children with weak secretor genotype se(385)se(385). Conclusions: These findings indicate that secretor positivity is significantly associated with GII.3 and GII.4 infections in Chinese pediatric diarrheal disease and the weak secretor phenotype does not completely protect children from GII.3 and GII.4 infections.