Rotavirus A genotype P[4]G2: Genetic diversity and reassortment events among strains circulating in Brazil between 2005 and 2009

Group A rotaviruses (RV‐A) are the leading cause of severe gastroenteritis in infants and young children worldwide. Due to the epidemiologic complexity of RV‐A, especially in developing countries, it is important to determine which genotypes are circulating, principally after the introduction in March 2006 of the monovalent (P[8]G1) Rotarix® vaccine in Brazil by the National Immunization Program. In Phase III trials with Rotarix®, the prevalence of genotype P[4]G2 was extremely low, and therefore, evaluation of heterotypic immunization against this genotype was performed by meta‐analysis statistics tests. Different studies have shown the re‐emergence of genotype P[4]G2 in Brazil, since 2005, as well as in other countries, suggesting that it could be a continental phenomenon related to the temporal variability in the genotype's naturally occurring distribution. It is important to note that genotype P[4]G2 does not share VP4 or VP7 antigens with the vaccine strain. Therefore, we performed a phylogenetic analysis based on VP4 (VP8*), VP7, VP6, and NSP4 genes of RV‐A genotype P[4]G2 samples isolated from the five regions of Brazil between 2005 and 2009. This study revealed that different genetic variants of RV‐A genotype P[4]G2 circulated in Brazil between 2005 and 2009, and that this variability is determined mainly by: occurrence of point mutations; reassortment events; and widespread global gene flow. The results obtained in this study are important to our understanding of the epidemiology and evolution of RV‐A genotype P[4]G2 and demonstrate the importance of continuous monitoring and molecular characterization of RV‐A strains circulating in human and animal populations. J. Med. Virol. 83:1093–1106, 2011. © 2011 Wiley‐Liss, Inc.