A decade of G3P[8] and G9P[8] rotaviruses in Brazil: epidemiology and evolutionary analyses

This study aims to estimate the frequency of group A rotaviruses (RVA) infection with genotypes G3P[8] and G9P[8] in children that suffered from diarrheal disease (DD) between 2001 and 2011 in different Brazilian regions. In addition, the genetic diversity of G3P[8] and G9P[8] RVA strains recovered from vaccinated and non-vaccinated children was assessed. Laboratory-based RVA surveillance included 15,115 cases of DD, and RVA was detected by enzyme immune-assay and/or polyacrylamide gel electrophoresis in 3357 (22%) samples. RVA was genotyped by the semi-nested RT-PCR and among RVA-positive samples, 100 (2.9%) were G3 (63 G3P[8], 32 G3P not typed [NT], and 5 G3P[6]) and 378 (16.2%) were G9 (318 G9P[8], 59 G9P[NT], and 1 G9P[6]). From the G3 and G9 positive samples, 16 and 12, respectively, were obtained from children aged 4-48months vaccinated with the monovalent vaccine (Rotarix®, RV1). Phylogenetic analyses of the VP7 and VP8(∗) encoding genes were performed for 26 G3P[8] and 48 G9P[8] strains. VP8(∗) phylogenetic analysis revealed that all strains analyzed belonged to P[8] lineage III, whereas RV1 belongs to P[8]-I lineage. VP7 analysis revealed that all G3 and G9 strains belonged to G3-lineage III and G9-lineage III. The comparison of the VP7 and VP8(∗) antigenic epitopes regions of Brazilian strains with RV1 strain revealed several amino acid changes. However, no particular differences among Brazilian strains detected before and after vaccine introduction were observed, or among strains detected from vaccinated and non-vaccinated children. Complete genome characterization of four G3P[8] and seven G9P[8] strains revealed a typical conserved human Wa-like genomic constellation. Changes in the genetic diversity of G3P[8] and G9P[8] RVA detected from 2001 to 2011 in Brazil seemed not be related to RV1 introduction in Brazil.