Malaria Parasite Sexual Development, Drug Resistance, and Evolution

我们已经完成了对恶性疟原虫全部14条染色体上3539个基因的单核苷酸多态(SNPs)的收集，并于今年早些时候发表在《自然遗传学》上。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处于宿主免疫选择(抗原)下的候选分子。基于已鉴定的SNPs，我们开发了一种微阵列平台(分子反转探针或平行等位基因)，使我们能够在单个杂交中对大量SNPs进行基因分型。寄生虫是从我们在柬埔寨的临床现场的患者身上收集的。许多寄生虫已经在体外培养中适应和生长。寄生虫的DNA样本正在准备进行杂交。我们还一直在评估一个拥有250万个探针的高密度微阵列，用于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分型的一个很好的替代方案。寄生虫对不同抗疟疾药物的反应正在接受测试，以确定可能导致耐药性的突变。 我们正在进行的另一个项目是ABC转运蛋白及其在农杆菌耐药性中的作用。在我们之前的研究中，我们从基因上敲除了与氯喹和奎宁耐药相关的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。 我们已经完成了对我们收集的ESTcDNA的数据分析。我们的数据显示恶性疟原虫的基因预测有相当大的误差。 在与墨西哥科学家的合作下，我们还一直在研究间日疟原虫种群及其在墨西哥南部的宿主特异性。结果表明，该地区间日疟原虫种群可分为三个种群，由两种不同蚊种传播，传播效率不同。这项研究可能为更好地理解寄生虫和宿主相互作用(或宿主特异性)的分子机制提供信息。 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.