RESUMO
The population of malaria-causing parasites is characterized by great genetic diversity. Knowledge of the polymorphism generation mechanism is a central issue for developing effective vaccines against malaria and understanding the parasite population structure. Plasmodium vivax genetic diversity has been explained in terms of two major factors: natural selection and intragenic recombination. A modular organization was found within P. vivax Duffy binding protein in the present work. Four Colombian isolates have identical sequences to Salvador-1 strain amongst dpb regions III-VI analysed, suggesting a high identity between Central and South American isolates. Geographically clustered sectors, corresponding to cysteine-rich regions (II and VI), show a high sequence diversity that could reflect a possible immune response evasion mechanism; both positive and negative selection were detected in these regions. In contrast, other dbp gene regions display a non-geographical clustering pattern, lower sequence diversity and predominant negative selective pressure. Recombination was homogeneously detected all along the molecule. These findings suggest that diversification vs. homogenizing forces, drive dbp gene evolution and determine its mosaic region organization.
Assuntos
Antígenos de Protozoários/genética , Malária Vivax/parasitologia , Plasmodium vivax/genética , Proteínas de Protozoários/genética , Receptores de Superfície Celular/genética , Sequência de Aminoácidos , Animais , Antígenos de Protozoários/química , Sequência de Bases , Análise por Conglomerados , DNA de Protozoário/química , DNA de Protozoário/genética , Variação Genética , Humanos , Dados de Sequência Molecular , Filogenia , Plasmodium vivax/metabolismo , Reação em Cadeia da Polimerase , Proteínas de Protozoários/química , Receptores de Superfície Celular/química , Seleção Genética , Alinhamento de Sequência , Propriedades de SuperfícieRESUMO
Functional and structural analyses of major histocompatibility complex (MHC) class I molecules of the Aotus genus are necessary to validate it as a solid animal model for biomedical research. We thus isolated, cloned and sequenced exons 2 and 3 from three Aotus species (A. nancymaae, A. nigriceps and A. vociferans). We found 24 sequences, which divided into two different groups (Ao-g1 and Ao-g2). A further sequence was identified as a processed pseudogene (Aona-PS2). Both sequence evolution and variability analyses showed that Ao-g1 and Ao-g2 display similar characteristics to Catarrhini's classical loci, such as positive selection pressure at the peptide binding region (PBR) high variability and a trans-specific evolution pattern.
