Identificação de novas possíveis variantes do Infectious Bursal Disease Virus (IBDV)

• Autor(a) principal: Félix, Francisney Silva
• Data de Publicação: 2010
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/2428
• topic: Infectious Bursal Disease; Infectious Bursal Disease; CNPQ::CIENCIAS BIOLOGICAS::BIOQUIMICA::BIOLOGIA MOLECULAR

The Brazilian poultry industry is the world s leading exporter of chickens meat. One of main agents causing losses is the virus of infectious bursal disease-IBDV, belonging to the family Birnaviridae.There are two serotypes of IBDV: serotypes 1 and 2, and all the viruses able to cause disease in birds belong to serotype 1. In Brazil, the virus has been responsible for large economic losses in poutry where only between 2005 and 2009 caused 237 outbreaks in Brazilian herds leading to death and sacrifice of 868,054 chickens. Infected, the chicken may have immunosupression, diarrhea, prostration, ruffled feathers and even come to death, and that mortality can vary depending on the viral strain, immune status and age of chicken. The outer capsid protein (VP2) of IBDV has a region that is called hypervariable which is used to characterization viral. Actually, the viral strains are classified as attenuated, (atIBDV), variant (avIBDV), highly virulent (vvIBDV), classical strain and wild type strain. The aim general of this study was to analyse the hypervariable region of VP2 in viral strain isolated from the bursa of Fabricius of chickens with suspect disease, from the tree municipality State of Minas Gerais. And to evaluate the possible occurrence of new variant lineages circulating in field. The virus was confirmed after a sequence of 472pb gene encoding VP2 was amplified by RT-PCR and sequenced. Of the eight evaluated samples, six of these samples which were positive for the virus had their sequences compared to other 98 available in Genbank, using the program ClustalW, to study the genetic diversity of these lineages. To analyse variations of amino acid residues, the sequence from these isolates were aligned with the amino acid sequence of other isolates characterized in the literature using the program CC Main Workbench Version 5.5 (CLC bio). The phylogenetic hypothesis was inferred by Bayesian Inference (BI) through the program MrBayes v3.1. The results showed that sequences of nucleotides taken from UFV were grouped into a unique clade in the phylogenetic tree due to variations in amino acids of VP2, differences sample of very virulent, wild type strains, classical strains and attenuated strains. Furthermore, differences in the hypervariable region of VP2 of these sequences samples when compared with the sequences of four vaccine strains available in GenBank showed that they can be treated to new viral variants that are circulating on commercial farms not having thus vaccination.Therefore, vaccination protocols should be reviewed in these herds.