Search

Although malaria parasites infecting non-human primates are important models for human malaria, little is known of the ecology of infection by these parasites in the wild. We extensively sequenced cytochrome b ( cytb) of malaria parasites (Apicomplexa: Haemosporida) from free-living southeast Asian monkeys Macaca nemestrina and Macaca fascicularis. The two most commonly observed taxa were Plasmodium inui and Hepatocystis sp., but certain other sequences did not cluster closely with any previously sequenced species. Most of the major clades of parasites were found in both Macaca species, and the two most commonly occurring parasite infected the two Macaca species at approximately equal levels. However, P. inui showed evidence of genetic differentiation between the populations infecting the two Macaca species, suggesting limited movement of this parasite among hosts. Moreover, coinfection with Plasmodium and Hepatocystis species occurred significantly less frequently than expected on the basis of the rates of infection with either taxon alone, suggesting the possibility of competitive exclusion. The results revealed unexpectedly complex communities of Plasmodium and Hepatocystis taxa infecting wild southeast Asian monkeys. Parasite taxa differed with respect to both the frequency of between-host movement and their frequency of coinfection. [ABSTRACT FROM AUTHOR]

Background: In malaria parasites (genus Plasmodium), ama-1 is a highly polymorphic locus encoding the Apical Membrane Protein-1, and there is evidence that the polymorphism at this locus is selectively maintained. We tested the hypothesis that polymorphism at the ama-1 locus reflects population history in Plasmodium vivax, which is believed to have originated in Southeast Asia and is widely geographically distributed. In particular, we tested for a signature of the introduction of P. vivax into the New World at the time of the European conquest and African slave trade and subsequent population expansion. Results: One hundred and five ama-1 sequences were generated and analyzed from samples from six different Brazilian states and compared with database sequences from the Old World. Old World populations of P. vivax showed substantial evidence of population substructure, with high sequence divergence among localities at both synonymous and nonsynonymous sites, while Brazilian isolates showed reduced diversity and little population substructure. Conclusion: These results show that genetic diversity in P. vivax AMA-1 reflects population history, with population substructure characterizing long-established Old World populations, whereas Brazilian populations show evidence of loss of diversity and recent population expansion. Note: Nucleotide sequence data reported is this paper are available in the GenBank database under the accession numbers EF031154 -- EF031216 and EF057446 -- EF057487. [ABSTRACT FROM AUTHOR]