Núcleo de Estudos em Malária, Superintendência de Controle de Endemias/Instituto de Medicina Tropical de São Paulo, Universidade de São Paulo, Brazil.
Acta Trop. 2012 Oct;124(1):27-32. doi: 10.1016/j.actatropica.2012.05.016. Epub 2012 Jun 15.
Plasmodium malariae is a protozoan parasite that causes malaria in humans and is genetically indistinguishable from Plasmodium brasilianum, a parasite infecting New World monkeys in Central and South America. P. malariae has a wide and patchy global distribution in tropical and subtropical regions, being found in South America, Asia, and Africa. However, little is known regarding the genetics of these parasites and the similarity between them could be because until now there are only a very few genomic sequences available from simian Plasmodium species. This study presents the first molecular epidemiological data for P. malariae and P. brasilianum from Brazil obtained from different hosts and uses them to explore the genetic diversity in relation to geographical origin and hosts. By using microsatellite genotyping, we discovered that of the 14 human samples obtained from areas of the Atlantic forest, 5 different multilocus genotypes were recorded, while in a sample from an infected mosquito from the same region a different haplotype was found. We also analyzed the longitudinal change of circulating plasmodial genetic profile in two untreated non-symptomatic patients during a 12-months interval. The circulating genotypes in the two samples from the same patient presented nearly identical multilocus haplotypes (differing by a single locus). The more frequent haplotype persisted for almost 3 years in the human population. The allele Pm09-299 described previously as a genetic marker for South American P. malariae was not found in our samples. Of the 3 non-human primate samples from the Amazon Region, 3 different multilocus genotypes were recorded indicating a greater diversity among isolates of P. brasilianum compared to P. malariae and thus, P. malariae might in fact derive from P. brasilianum as has been proposed in recent studies. Taken together, our data show that based on the microsatellite data there is a relatively restricted polymorphism of P. malariae parasites as opposed to other geographic locations.
疟原虫是一种原生动物寄生虫，可导致人类疟疾，其遗传特征与感染中美洲和南美洲新世界猴的寄生虫疟原虫巴西亚种无法区分。疟原虫广泛分布于全球热带和亚热带地区，在南美洲、亚洲和非洲都有发现。然而，人们对这些寄生虫的遗传特征知之甚少，它们之间的相似性可能是因为到目前为止，只有非常少数的灵长类疟原虫的基因组序列可用。本研究首次从巴西不同宿主中获得了疟原虫和疟原虫巴西亚种的分子流行病学数据，并利用这些数据探讨了与地理起源和宿主相关的遗传多样性。通过使用微卫星基因分型，我们发现从大西洋森林地区获得的 14 个人类样本中记录了 5 种不同的多位点基因型，而在同一地区感染蚊子的样本中发现了不同的单倍型。我们还分析了两名未经治疗的非症状患者在 12 个月间隔内循环疟原虫遗传谱的纵向变化。来自同一患者的两个样本中的循环基因型具有几乎相同的多位点单倍型（仅在一个基因座上存在差异）。在人类中，更为常见的单倍型几乎持续了 3 年。先前描述的作为南美疟原虫遗传标记的 Pm09-299 等位基因在我们的样本中并未发现。在亚马逊地区的 3 个非人类灵长类动物样本中，记录了 3 种不同的多位点基因型，表明与疟原虫巴西亚种相比，疟原虫巴西亚种的分离株具有更大的多样性，因此，如最近的研究中所提出的，疟原虫实际上可能源自疟原虫巴西亚种。总之，我们的数据表明，根据微卫星数据，与其他地理位置相比，疟原虫寄生虫的相对限制多态性。
