title: Tracking the molecular epidemiology of Brazilian Infectious bursal disease virus (IBDV) isolates.
abstract: Infectious bursal disease is a highly contagious disease of young chickens caused by Infectious bursal disease virus (IBDV). Genome segment A encodes the capsid protein (VP2), while segment B encodes the RNA-dependent RNA polymerase (VP1). In the present study, we trace the molecular epidemiology of IBDV in Brazil by analyzing 29 isolates collected in the major regions of poultry production. To genetically characterize the isolates, phylogenetic and population dynamic analyses were conducted using 68 VP1 (2634 nt) and 102 VP2 (1356 nt) coding sequences from IBDV isolates from different regions of the world. Furthermore, the evolution of IBDV was analyzed by characterizing the selective forces that operated during the diversification of viral isolates. We show that IBDV isolates were introduced into Brazil mainly from the Netherlands and the USA. These introductions were associated with all Brazilian poultry production regions analyzed in this work. In addition, we show that the evolution of IBDV has been shaped by a combination of very low recombination rates and relatively high rates of nucleotide substitution (2.988×10(-4) for VP1 and 3.2937×10(-4) for VP2), which themselves are a function of purifying selection operating on VP1 and VP2. Furthermore, our extended Bayesian skyline plot suggests that the increase in the effective population size of isolates of IBDV is consistent with its epidemiological history, with a large increase during the emergence of acute outbreaks of IBD in the 1980s.
authors.affiliation: Molecular Animal Infectology Laboratory, Institute of Applied Biotechnology to Agriculture (BIOAGRO), Federal University of Vicosa, Vicosa 36570-000, Brazil.
authors.forename: Fernanda M F
authors.initials: FM
authors.lastname: Silva
authors.forename: Pedro M P
authors.initials: PM
authors.lastname: Vidigal
authors.forename: Luciana W
authors.initials: LW
authors.lastname: Myrrha
authors.forename: Juliana L R
authors.initials: JL
authors.lastname: Fietto
authors.forename: Abelardo
authors.initials: A
authors.lastname: Silva
authors.forename: Márcia R
authors.initials: MR
authors.lastname: Almeida
mesh_terms: D000818:Animals; D018175:Birnaviridae Infections / Q000453:epidemiology*; D001938:Brazil / Q000453:epidemiology; D059765:Homologous Recombination; D007243:Infectious bursal disease virus / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification; D008969:Molecular Sequence Data; D059645:Mutation Rate; D010802:Phylogeny; D011201:Poultry Diseases / Q000453:epidemiology*; D012641:Selection, Genetic; D015678:Viral Structural Proteins / Q000235:genetics; D014774:Virulence / Q000235:genetics
chemical_list: C107669:VP1 protein, infectious bursal disease virus; C082513:VP2 protein, infectious bursal disease virus; D015678:Viral Structural Proteins