Malaria Parasite Sexual Development, Drug Resistance, and Evolution

我们已经完成了从恶性疟原虫所有14条染色体上的3539个基因中收集单核苷酸多态性（SNP）的工作，并于今年早些时候在《自然遗传学》上发表了论文。除了开发全基因组SNP图谱外，我们的研究还确定了许多可能受到宿主免疫选择（抗原）的候选分子。基于所鉴定的SNPs，我们开发了一种微阵列平台（分子倒置探针或PArAllele），该平台允许我们在单次杂交中对大量SNPs进行基因分型。我们正在柬埔寨的临床现场从患者身上收集寄生虫。许多寄生虫已经适应并在体外培养中生长。寄生虫的DNA样本正在准备用于杂交。我们也一直在评估一个高密度微阵列与250万探针的基因分型和其他研究。我们的数据表明，这种高密度阵列可能是SNP分型的一个很好的选择。正在测试寄生虫对不同抗疟药物的反应，以确定可能导致抗药性的突变。 我们正在研究的另一个项目是ABC转运蛋白及其在恶性疟原虫耐药性中的作用。在我们先前的研究中，我们已经从基因上敲除了与氯喹和奎宁抗性相关的ABC转运蛋白之一，并正在评估基因敲除对寄生虫药物反应的影响。 我们已经完成了我们的ESTcDNA收集的数据分析。我们的数据显示恶性疟原虫中相当大的基因预测不准确。 我们还与墨西哥的科学家合作，研究了墨西哥南部的间日疟原虫种群及其宿主特异性。结果表明，该地区间日疟原虫可分为3个种群，由两种不同蚊种传播，传播效率不同。本研究为深入了解寄生虫与宿主相互作用的分子机制（或宿主特异性）提供了信息。 我们仍然对寄生虫性发育的各个方面感兴趣，特别是Pfmdv1和其他可能参与配子体发育过程的基因的生物学功能。

We have finished collecting single nucleotide polymorphisms (SNPs) from 3539 genes on all of the 14 chromosomes of Plasmodium falciparum, leading to a publication in Nature Genetics early this year. In addition to developing genome-wide SNP map, our study also identified many candidate molecules that could be under host immune selection (antigens). Based on the SNPs identified, we have developed a microarray platform (Molecular Inversion Probe or PArAllele) that allows us to genotype large numbers of SNPs in a single hybridization. Parasites are being collected from patients at our clinical field site in Cambodia. Many of the parasites have been adapted and grown in in vitro culture. DNA samples from the parasites are being prepared for hybridization. We also have been evaluating a high-density microarray with 2.5 million probes for genotyping and other studies. Our data suggested that this high-density array could be a good alternative for SNP typing. The parasite responses to different antimalarial drugs are being tested to identify mutations potentially contributing to drug resistances. Another project we are working on is ABC transporters and their roles in drug resistance in P. falaciprum. We have genetically knockout one of the ABC transporters associated with chloroquine and quinine resistances in our pervious study and are evaluating the effects of gene knockout on parasite drug responses. We have finished the data analyses of our ESTcDNA collection. Our data showed considerable gene prediction inaccuracy in the P. falciparum. In collaboration with scientists in Mexico, we have also been studying Plasmodium vivax populations and their host specificity in Southern Mexico. Our data showed that P. vivax population there could be divided into three populations that were transmitted by two different mosquito species with different efficiency. This study can potentially provide information for better understanding of the molecular mechanisms of parasite and host interaction (or host specificity). We are still interested in various aspects of parasite sexual development, particularly the biological functions of Pfmdv1 and other genes that may involve in the process of gametocyte development.