Partial VP1 sequencing of Brazilian infectious bursal disease virus strains

• Main Authors: Maria Judite Bittencourt Fernandes, Isabela Cristina Simoni, Ricardo Harakava, Eliana Borges Rivas, Clarice Weis Arns
• Format: Article
• Language: English
• Published: Sociedade Brasileira de Microbiologia 2012-09-01
• Series: Brazilian Journal of Microbiology
• Subjects: Brazilian infectious bursal disease virus; very virulent strain; VP1; sequencing; phylogenetic analysis
• Online Access: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1517-83822012000300024

Infectious bursal disease virus (IBDV) is classified according to the antigenicity and virulence into classical virulent (cv), very virulent (vv), and antigenic variant strains. The molecular basis for the IBDV antigenic variation is well established and is associated to the capsid protein, VP2 (gene VP2 of segment A), whereas both VP2 and the RNA-dependent RNA polymerase, VP1 (gene VP1 of segment B), have been correlated with the virulence. In this study, seventeen Brazilian IBDV samples previously characterized by the VP2 gene as cv (three) and vv (fourteen) strains were genetically and molecularly analyzed for their VP1 gene. All of the strains kept with the same cv or vv classification except one sample, Br/03/DR. This sample was classified as vv by its VP2 gene, but it was most closely related to the cv strains by its VP1 partial sequence and phylogeny. Studies on the phylogeny of VP1 have suggested a possible reassortment event that originated the vvVP1. In this case, the sample carrying vvVP2 and cvVP1 could be a descendant of IBDV ancestors prior to the reassortment of vvVP1; alternatively, it could be the result of a genetic exchange between the segments of different strains or with a live attenuated vaccine. Nevertheless, this is the first report of natural genetic reassortment of IBDV in Brazil.