Estudo filogenético do gene apxIA de Actinobacillus pleuropneumoniae sorotipo 5 isolados no Brasil

• Autor(a) principal: Santos, Lucas Fernando dos
• Data de Publicação: 2011
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/5063
• topic: apxIA; Fatores de virulência; Diversidade genética; apxIA; Virulence factors; Genetic diversity; CNPQ::CIENCIAS AGRARIAS::MEDICINA VETERINARIA

The toxins produced by Actinobacillus pleuropneumoniae (App) are recognized as major virulence factors found in this pathogen. Apx toxin I has strong hemolytic and cytotoxic activity, and this toxin has a high cytotoxic activity against pulmonary macrophages and neutrophils in swine. This exotoxin is produced by different serotypes, including the serotypes 1, 5, 9, 10, 11 and 14, which are involved with the most severe reported clinical cases. In general, these toxins are encoded by operons consisting of four genes: C, A, B and D, where the gene A encoding the structural proteins. The molecular basis of evolution and genetic diversity among the serotypes of App are not well understood. One of the possible explanations for this can be unavailability of DNA sequences of this bacteria in public databases. Thus, this study aimed to sequence the gene apxIA and assess the genetic diversity of this gene in isolates of the App with reference sequences available in GenBank (NCBI). In this study, we analyzed 42 isolates of serotype App 5A and 5B. The sequences of these isolates were compared with other sequences available in GenBank databases using the program MUSCLE 3.8.31 and polymorphisms of the nucleotide and amino acid sequences were analyzed. The nucleotide substitution model used was F81 + I + G, estimated from the set of sequences aligned using the program jModeltest 0.1.1. The results showed the presence of differences in the ApxI sequences that allowed group the 41 Brazilian isolates in 14 haplotypes (groups of sequences with 100% identity). Brazilian isolates were grouped into two groups (1 and 2), being distinguished by mutations in the amino acid residues 2 and 3 of protein ApxI. These results indicate the existence of a genetic diversity among isolates of App and can assist in the development of more efficient vaccine candidates.