Diversidade genética de norovírus em indivíduos com diarreia aguda: uma análise temporal
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2019-10-25
Autores
Barreira, Debora Maria Pires Goncalves
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Universidade Federal do Espírito Santo
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Human noroviruses, belonging to three genogroups and more than 30 genotypes, are the main cause of sporadic gastroenteritis and outbreaks worldwide. They are characterized by significant evolution due to mutation and recombination events, and generation of pandemic-spreading variants. The aim of this study was to determine the genetic diversity of noroviruses in individuals with gastroenteritis in our geographic area. Three groups of samples were included in this study: (i) fecal specimens obtained prospectively from children with diarrhea (n=307) collected between October 2014 and September 2018; (ii) norovirus-positive specimens (n=78) obtained from children and adults between February 2003 and June 2004 and December 2007 and June 2011; and (iii) norovirus-positive specimens (n=2) associated with a gastroenteritis outbreak in a hospital unit in 2012. Norovirus detection was performed by RT-qPCR for the ORF1-ORF-2 junction region. Genotypes were determined by phylogenetic analysis of partial polymerase and capsid sequences. Complete sequence of the capsid protein (VP1) GII.4 Sydney 2012 and nearly complete sequence of the GII.P16 polymerase of the new recombinant GII.4 Sydney [P16] were obtained and phylogenetic analysis performed. Noroviruses were detected in 24.4% (75/307) of the prospective study specimens and phylogenetic analysis (n=52) demonstrated the predominance of the recombinant GII.P16 GII.4 Sydney 2012 (n=27), described for the first time in Brazil, followed by genotypes GII.4 Sydney 2012[P31] (n=10) and GII.17[P17] (n=5), in addition to seven other recombinants in a smaller number of cases (GII.2[P16], GII.6[P7], GII.3[P16], GII.4 Sydney 2012[PNA], GII.1[Pg], GII.4 Sydney 2012[P4 New Orleans] and GI.7[P7]). There were amino acid substitutions in the proteins: (i) GII.P16 polymerase of strains that circulated in 2016 and 2017 compared with pre-2015 sequences (available in GenBank); and in (ii) VP1 of GII.4 Sydney 2012 strains associated with GII.P16 (2016 and 2018) compared with those associated with GII.P31 before 2015. Different GII.4 variants were detected in all sample collection periods, coinciding with their circulation worldwide. The recombinant GII.4 Sydney 2012[P31] was responsible for the outbreak in the hospital, which occurred in the same year of its first description worldwide. Our study shows the great genetic diversity of noroviruses circulating in our geographic area and highlights the unprecedented report of the emerging recombinant GII.4 Sydney 2012[P16] in Brazil. Evolutionary algorithms applied to passive optical network designs
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Gastroenterite