Estudo filogeográfico e análise comparativa dos modelos de classificação do Porcine circovirus-2 (PCV-2).

• Autor(a) principal: Vidigal, Pedro Marcus Pereira
• 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/123456789/2465
• topic: Porcime circovirus-2; PCV-2; PCVAD; PMWS; Filogeografia; Porcime circovirus-2; PCV-2; PCVAD; PMWS; Phylogeography; CNPQ::CIENCIAS AGRARIAS::MEDICINA VETERINARIA::MEDICINA VETERINARIA PREVENTIVA

The pig infectious agents have received great attention since the last decade, when many pig producing countries accumulated economic losses due to pathogens such as Porcine circovirus-2 (PCV-2). The PCV-2 is a virus classified in Circoviridae family and is associated with a number of different syndromes in pigs called Porcine Circovirus Associated Diseases (PCVAD). Since its identification and characterization, PCV-2 has reached a worldwide distribution and the PCVAD became a syndrome endemic in most producer countries and currently considered the main cause for losses on pig farms. In this study, the nomenclatures proposed for the classification of viral isolates were compared, and the spread routes of PCV-2 among pig producing countries were analyzed. A search for genomic sequences of PCV-2 was performed in GenBank and 350 sequences of viral isolates were randomly selected. The classification model of PCV-2 in genotypes, recommended by the European consortium that studies the Porcine circovirus diseases (PCVD) and defined by analysis of mismatch distribution, and the classification model in phylogenetic subgroups, an alternative model defined by phylogenetic hypotheses, were applied to the set of selected sequences. Both in the mismatch distribution analysis and in the phylogenetic analysis, the groups formed and the changes observed were very similar. In these analyses, there was an overlap between genotypes and phylogenetic subgroups. The genotype PCV-2a was equivalent to Group 2 and grouped the subgroups 2A, 2B, 2C, 2D and 2E. The genotype PCV-2b was equivalent to Group 1 and grouped the subgroups 1A, 1B and 1C. The genotype PCV- 2c only grouped the sequence of the viral isolate that defines it. These results show that the existing subdivisions in the genotypes of PCV-2a and PCV-2b should not be neglected for don ́t underestimate the genetic diversity among isolates of PCV-2. In the phylogeographic study, the spread routes of PCV-2 were predicted through phylogenetic and phylogeographic approaches. In phylogenetic analysis, the phylogenetic trees were calculated by Bayesian inference and the isolates were grouped in the genotypes PCV-2a, PCV-2b and PCV-2c. In phylogeographical analysis, a haplotype network was calculated by Median Joining algorithm for the establishment of genealogy among the viral isolates, and the spread routes of PCV-2 among the countries were predicted. To support these analyses, two databases were organized. The first database grouped all available information on the isolates of PCV-2 in GenBank and in publications related to viral isolation. The second data set grouped the statistics of live pigs trade available at United Nations Commodity Trade Statistics Database DESA/UNSD and was organized to establish an economic context to establish an economic context in the phylogeographic analysis. From these analyses, the following spread routes of PCV-2 were predicted: North America → Africa, North America → South America, North America → Caribbean, Europe → North America, Europe → South America, Europe → Asia, Oceania → Asia and Oceania → North America. In these spread routes, the main countries of origin of the routes are Canada, United States, Denmark, France and the Netherlands, that are the major exporters of animals in the international trade of live pigs. In this study, were identified correlations between the means of dispersal of PCV-2 in pigs predicted by the phylogeographic context and the statistics on international trade in live pigs. This correlation shows the importance of the movement of animals in the world to the emergence of new pathogens and the need to establish sanitary barriers that are increasingly effective for trade in animals.