Group A rotavirus (RVA) is the most viral agent associated with acute gastroenteritis, responsible for about 200,000 deaths among children aged under five years annually. RVA belongs to Reoviridae family, Rotavirus genus, its genome is composed by double-stranded RNA (dsRNA) with 11 segments encoding 12 proteins, six structural (VPs) and six non-structural (NSPs). Each protein designating a specific RVA genotype, being VP7 protein responsible for G genotype and currently there are 32 genetic variants. G9 genotype emerged on a global scale in the 90s, a period before RVA vaccine introduction in Brazil that occurred in 2006, and is continuously detected until present day. This study aimed to describe the frequency and genetic constellation associated with the current G9 genotype in Northern Brazil. It was selected 50 samples collected between 1999 and 2013, being 45 G9P[8], 2 G9P[4] and 3G9P[6], for fecal suspension preparation and dsRNA extraction for further genome amplification and sequencing of nucleotides. It was observed that during pre-RVA vaccine introduction period G9 frequency rate was 43%, while after RVA vaccine introduction the most frequece obtained was 12.5% (2008 to 2010). Phylogenetic analysis of VP7 gene showed that all strains belong to lineage III of G9, observing aminoacidic substitutions in antigenic sites when compared with vaccine strains. It was demonstrated in VP4 gene that P[8] strains gathered in lineage III, whereas P[4] grouped into lineage V and P[6] strains into lineage I. All G9P[6] and G9P[4] samples were associated with DS-1 constellation, genogroup 2, while G9P[8] samples showed Wa constellation, genogroup 1, except for one sample showing NSP3 gene with DS-1 profile. G9 samples from Northern region analyzed were associated with the expected constellations described in other parts of the world, except for one G9P[8] sample that showed a genetic restructuration in NSP3 protein. In the present study the same G9 lineages have circulated during pre and post RVA vaccine introduction periods, and it was described aminoacidic substitutions in relevant antigenic regions, such as it was reported genetic restructuration phenomenon in one sample of this genotype, emphasizing the continuous monitoring of current genetic variants of RVA.
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