RESUMO

The malarial parasite Plasmodium vivax causes disease in humans, including chronic infections and recurrent relapses, but the course of infection is rarely fatal, unlike that caused by Plasmodium falciparum. To investigate differences in pathogenicity between P. vivax and P. falciparum, we have compared the subtelomeric domains in the DNA of these parasites. In P. falciparum, subtelomeric domains are conserved and contain ordered arrays of members of multigene families, such as var, rif and stevor, encoding virulence determinants of cytoadhesion and antigenic variation. Here we identify, through the analysis of a continuous 155,711-base-pair sequence of a P. vivax chromosome end, a multigene family called vir, which is specific to P. vivax. The vir genes are present at about 600-1,000 copies per haploid genome and encode proteins that are immunovariant in natural infections, indicating that they may have a functional role in establishing chronic infection through antigenic variation.

Assuntos

Genes de Protozoários , Plasmodium vivax/genética , Adulto , Animais , Anticorpos Antiprotozoários/imunologia , Cromossomos Artificiais de Levedura , DNA de Protozoário , Biblioteca Gênica , Variação Genética , Humanos , Malária Vivax/parasitologia , Família Multigênica , Plasmodium falciparum/genética , Plasmodium falciparum/patogenicidade , Plasmodium vivax/imunologia , Plasmodium vivax/patogenicidade , Proteínas de Protozoários/genética , Proteínas de Protozoários/imunologia , Pseudogenes , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Telômero