Abstract
Noroviruses are considered an important cause of acute gastroenteritis (AGE) across all age groups. Here, we investigated the incidence of norovirus, genotypes circulation, and norovirus shedding in AGE stool samples from outpatients in Brazil. During a two-year period, 1546 AGE stool samples from ten Brazilian states were analyzed by RT-qPCR to detect and quantify GI and GII noroviruses. Positive samples were genotyped by dual sequencing using the ORF1/2 junction region. Overall, we detected norovirus in 32.1% of samples, with a massive predominance of GII viruses (89.1%). We also observed a significant difference between the median viral load of norovirus GI (3.4×105 GC/g of stool) and GII (1.9×107 GC/g). The most affected age group was children aged between 6 and 24 m old, and norovirus infection was detected throughout the year without marked seasonality. Phylogenetic analysis of partial RdRp and VP1 regions identified six and 11 genotype combinations of GI and GII, respectively. GII.4 Sydney[P16] was by far the predominant genotype (47.6%), followed by GII.2[P16], GII.4 Sydney[P31], and GII.6[P7]. We detected, for the first time in Brazil, the intergenogroup recombinant genotype GIX.1[GII.P15]. Our study contributes to the knowledge of norovirus genotypes circulation at the national level, reinforcing the importance of molecular surveillance programs for future vaccine designs.
Highlights
Acute gastroenteritis (AGE) remains one of the major causes of childhood deaths worldwide [1,2]
Norovirus genus is currently divided into ten genogroups (GI-GX) and subdivided into over 40 genotypes based on the amino acid sequence of the VP1 protein [9]
We provided results on the incidence of norovirus infections among outpatients with AGE from ten Brazilian states that represent around 100 million inhabitants (almost with AGE from ten Brazilian states that represent around 100 million inhabitants, in addition to virological and molecular epidemiological half of the country’s population), in addition to virological and molecular epidemiological features of these infections
Summary
Acute gastroenteritis (AGE) remains one of the major causes of childhood deaths worldwide [1,2]. After the global introduction of the rotavirus vaccine, noroviruses have been considered the most important cause of outbreaks of viral AGE [5,6]. These norovirus-related outbreaks are frequently reported in semi-enclosed and closed settings such as hospitals, cruise ships, long term care facilities, and schools [7]. Noroviruses belong to the family Caliciviridae (genus Norovirus) and are nonenveloped, positive-sense RNA viruses with a 7.5kb genome that is organized into three open reading frames (ORFs 1–3). While over 30 different genotypes from GI, GII, GIV, GVIII, and GIX can infect humans, a single genotype (GII.4) is responsible
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