Detection of the emerging rotavirus G!@P(8) genotype at high frequency in brazil in 2014: Successive replacement of predominant strains after vaccine introduction

The continuum characterization of rotavirus (RVA) genotypes is essential to understand how vaccine introduction could impact virus epidemiology. In the present study, an unexpected rapid changing pattern of RVA genotypes distribution in Brazilian population during three followed seasons is described. From January/2012 to December/2014, a total of 3441 fecal specimens were collected from collaborating centers across Southern, Southeastern and Midwest of Brazil. All specimens were screened for RVA using ELISA, and genotyped by RT-PCR. Differences in proportions were tested using Chi-Squares. A p-value of less than 0.05 was considered statistically significant. RVA was detected in 19.7% (677/3441). Among RVA positive cases (n=677), a total of 652 (96.3%) samples were successfully amplified by RT-PCR. G3P[8] remained prevalent in 2012 (37.6%, 69/185) and 2013 (40.1%, 74/186) (χ(2)=0.107, p=0.743), but declined markedly in 2014 (3.5%, 10/281) (χ(2)=71.770, p=0.000). G12P[8] was second highest strain in 2012 (22.7%, 42/185), decrease rapidly in 2013 (2.7%, 5/186) (χ(2)=26.224, p=0.000) and re-emerged as the predominant genotype in 2014 (86.6%, 243/281) (χ(2)=118.299, p=0.000). From July/2014, G12P[8] was the single genotype detected in all regions studied. The sudden emergence, spread and predominance of G12P[8] strain in Brazil, raised the hypothesis of a possible G12 outbreak being in progress. Nationally, the long term decline in gastroenteritis hospitalization observed in the country after RVA vaccine introduction was confirmed. Nevertheless, the sharp increase in diarrhea hospitalization prevalence from 2013 to 2014 observed in Southern and Southeastern regions is consistent with what appears to be an outbreak of G12P[8]. Continued surveillance is needed to verify the effectiveness of the RotarixTM vaccine in Brazil together with potential emergence of unusual genotypes.

Phylogenetic analysis of human group C rotavirus circulating in Brazil reveals a potential unique NSP4 genetic variant and high similarity with Asian strains

Group C rotaviruses (RVC) cause gastroenteritis in humans and animals worldwide, and the evidence for a possible zoonotic role has been recently provided. To gain information on the genetic diversity and relationships between human and animal RVC, we sequenced the VP4, VP7, and NSP4 genes of 12, 19, and 15 human strains, respectively, detected in São Paulo state during historical (1988 and 1993) and recent (2007 and 2008) Brazilian rotavirus surveillance. All RVC strains analyzed in the present study grouped into human genotype (G4-P[2]-E2), and did not show any evidence of animal ancestry. Phylogenetic analysis showed that RVC samples detected in 1988 and 1993 clustered together with strains from distinct continents, indicating that historical RVC strains circulating in São Paulo were closely related to those strains circulating worldwide. All three genes (VP7, VP4 and NSP4) of São Paulo RVC strains isolated in 2007-2008 exhibited close phylogenetic relationship with human RVC strains isolated in China and Japan, suggesting that they are genetically linked, and that a gene flow could be occurring between this Asian countries and Brazil. We identified two distinct clusters in the NSP4 phylogenetic tree. One cluster formed exclusively by human Brazilian strains detected in 1997 and 2003-2004 in Rio de Janeiro, Bahia, and Rio Grande do Sul states (Subgroup II) previously described in a different study, that displayed low sequence identities to other human strains formerly published, and to the Brazilian RVC strains (Subgroup I) characterized in the present study. These data suggests the circulation of two genetic profiles of the NSP4 gene in Brazil. High sequence diversity in NSP4 gene was previously reported in Asia, and additional diversity in NSP4 RVC strains spreading in the world should be expected. More in-depth molecular and epidemiological analysis of human RVC throughout the world will be needed to understand their diversity and clarify their evolution, as well as to develop classifications schemes.

Rotavirus genotypes and the indigenous children of Brazilian midwest in the vaccine era, 2008-2012: footprints of animal genome

World group A rotavirus (RVA) surveillance data provides useful estimates of the disease burden, however, indigenous population might require special consideration. The aim of this study was to describe the results of G­ and P­types from Brazilian native children ≤3 years. Furthermore, selected strains have been analyzed for the VP7, VP6, VP4, and NSP4 encoding genes in order to gain insight into genetic variability of Brazilian strains. A total of 149 samples, collected during 2008­2012, were tested for RVA using ELISA and PAGE, following by RT­PCR and sequencing. RVA infection was detected in 8.7% of samples (13/149). Genotype G2P[4] was detected in 2008 and 2010, G8P[6] in 2009, and G3P[8] in 2011. The phylogenetic analysis of the VP7 and VP4 genes grouped the Brazilian G2P[4] and G3P[8] strains within the lineages currently circulating in humans worldwide. However, the phylogenetic analysis of the VP6 and NSP4 from the Brazilian G2P[4] strains, and the VP7 and NSP4 from the Brazilian G3P[8] strains suggest a distant common ancestor with different animal strains (bovine, caprine, and porcine). The epidemiological and genetic information obtained in the present study is expected to provide an updated understanding of RVA genotypes circulating in the native infant population, and to formulate policies for the use of RVA vaccines in indigenous Brazilian people. Moreover, these results highlight the great diversity of human RVA strains circulating in Brazil, and an in­depth surveillance of human and animal RVA will lead to a better understanding of the complex dynamics of RVA evolution