Examination of In Vivo Mutations in VP4 (VP8*) of the Rotarix® Vaccine from Shedding of Children Living in the Amazon Region

Group A rotaviruses (RVAs) remain the leading cause of acute gastroenteritis (AGE) in young children in low- and middle-income countries. In Brazil, the oral attenuated RVA vaccine (Rotarix^®), monovalent genotype G1P[8], is distributed by the national immunization program and has drastically reduced morbidity and mortality associated with RVA etiology. In this study, Rotarix^® G1P[8] was detected using specific qRT-PCR from the fecal shedding of children living in the Amazon region, and 18.3% (29/158) were positive and 75.8% (22/29) presented with AGE. The VP4 (VP8*) gene of these sheddings, submitted to Sanger nucleotide sequencing, showed an occurrence of mutations, including the silent mutation at 144C > G (one child) and the following missense mutations- 499T > C (F167L) (two children), 644G > C (C215S) (one child), and 787G > A (E263K) (one child). These mutations had no impact on the protein model structure in silico deduced from the VP4 (VP8*) mutants. The in silico protein model deduced from the VP4 (VP8*) nucleotide sequences, bound to type 1H sugar antigens (H1) and its precursor Lac-para-N-biose (LNB), had a stronger binding to the G1P[8] genotype, when compared to G3P[8]. Rotarix^® shedding was higher in HBGA secretors than in non-secretors (79.3%; 23/29). A total of 11.4% (18/158) of children with Rotarix^® G1P[8] shedding were unvaccinated, indicating the occurrence of indirect protection. Stability evidence of Rotarix^® VP4 (VP8*) spike protein from samples collected in vivo is presented.