Recombinant Noroviruses Detected in Mid-West Region of Brazil in Two Different Periods 2009-2011 and 2014-2015: Atypical Breakpoints of Recombination and Detection of Distinct GII.P7-GII.6 Lineages.

Noroviruses are an important cause of acute gastroenteritis. The high incidence of norovirus is a reflection of its great genomic and antigenic variability resultant of evolutionary mechanisms, such as recombination. Herein, the main objective of this study was to characterize partially two regions of norovirus genome (RdRp and VP1) from fecal samples, collected in two different time periods (2009-2011 and 2014-2015) in the Mid-West region of Brazil. Twenty samples were sequenced and characterized (GI.P5-GI.5, GII.P16-GII.3, GI.P7-GI.7, GII.Pe-GII.4 and GII.P7-GII.6). Sequences of GII.Pe-GII.4 genotype were also characterized as Sydney 2012 variant. Genotypes GII.P7-GII.6, GII.P16-GII.3 and GII.Pe-GII.4 (16/20-80%) were identified as norovirus recombinants by phylogeny and bioinformatic analyzes. The GII.P7-GII.6 (62.5%) and GII.Pe-GII.4 (25%) genotypes had recombination point's upstream ORF1/2 overlapping region, whereas GII.P16-GII.3 (12.5%) genotype had the recombination point in the overlapping region. Furthermore, the GII.P7-GII.6, from samples collected in 2009-2011 had different recombinant points than the GII.P7-GII.6 from samples obtained in 2014-2015, forming two different clusters in the phylogenetic analysis. Our study brings information on the circulation of recombinant norovirus genotypes in Mid-West of Brazil, including recombinants with atypical recombination breakpoints, and provides evidence for the circulation of different lineages of the same recombinant genotype.