Genetic Association Mapping of Malaria Resistance in Anopheles gambiae

描述（由申请人提供）：非洲冈比亚按蚊系谱的遗传连锁图谱发现了一个小的疟原虫抗性岛（PRI），该岛控制着蚊子对恶性疟原虫感染抗性的大部分自然遗传变异。PRI在2L染色体上占据-15兆碱基对。家谱分析是初步发现耐药位点的有效方法，但家谱不包含足够的重组信息，无法从抗性岛内的1000个基因中确定实际的致病基因。相比之下，遗传关联方法利用自然群体中的历史重组来剖析一个位点到单基因水平。在此，我们提出了一项遗传关联研究，以确定控制冈比亚疟对恶性疟原虫抗性和易感性的潜在特异性基因，目的如下：目的1，我们将通过在昆虫体内饲养野生捕获的冈比亚疟幼虫，并用自然感染志愿者血液中的恶性疟原虫挑战它们来构建关联小组。目的2，我们将开展一项间接关联研究，以缩小控制抗性的目标区间，使用微卫星和单核苷酸多态性作为中性标记。第三步，我们将通过对第二步中确定的部分或全部缩小的候选区域进行重测序，开展直接关联研究，以检测在自然界中控制蚊子对疟原虫的抗性和易感性的基因。由此产生的信息将允许对蚊子种群中基因易感的部分进行特定的区分。先前的系谱连锁研究表明，有效的遗传抗性机制在媒介种群中广泛存在，并表明实际的疟疾传播是由一个离散的遗传易感蚊子亚群进行的。我们提出，有可能开发一种新的疟疾控制形式，其基础是专门针对易感人群，以减少其在媒介种群中的频率。

DESCRIPTION (provided by applicant): Genetic linkage mapping of Anopheles gambiae pedigrees in Africa identified a small Plasmodium- Resistance Island (PRI) of the genome that controls most of the natural genetic variation for mosquito resistance to Plasmodium falciparum infection. The PRI occupies -15 megabase pairs on chromosome 2L. Pedigree analysis was an efficient method for initial discovery of resistance loci, but pedigrees do not contain enough recombinational information to genetically identify the actual causative gene(s) among the 1,000 genes within the resistance island. In contrast, the method of genetic association takes advantage of historic recombination in the natural population to dissect a locus to the single-gene level. Here we propose a genetic association study to identify the underlying specific genes that control resistance and susceptibility of A. gambiae to P. falciparum in nature, with the following Aims. Aim 1, we will construct an association panel by rearing wild-caught A. gambiae larvae in the insectary, and challenging them with P. falciparum from the blood of naturally-infected volunteers. Aim 2, we will carry out an indirect association study to narrow the target interval controlling resistance, using as neutral markers microsatellites and single-nucleotide polymorphisms. Aim 3, we will carry out a direct association study by resequencing part or all of the narrowed candidate region ascertained in Aim 2, to detect the genes that underlie control of mosquito resistance and susceptibility to malaria parasites in nature. The resulting information will allow specific discrimination of the genetically susceptible fraction of the mosquito population. The previous pedigree linkage study indicated that efficient mechanisms of genetic resistance are widespread in the vector population, and suggested that actual malaria transmission is carried out by a discrete subset of genetically susceptible mosquitoes. We propose that it may be possible to develop a novel form of malaria control based on specifically targeting the susceptibles to reduce their frequency in the vector population. Relevance: It may be possible to develop new strategies for malaria control focusing on the mosquito vector. Knowledge of the genetic mechanisms that affect transmission of malaria by vector mosquitoes would aid in the development of such vector-based control strategies.