Endogenous insulin-like peptides and control of malaria infection in the mosquito

描述(申请人提供)：冈比亚按蚊是撒哈拉以南非洲致命的人类疟疾寄生虫恶性疟原虫的主要媒介。虽然许多实验室研究都集中在蚊子免疫系统如何应对和摧毁这些寄生虫，但目前几乎没有关于这些反应在自然条件下是否重要的现有信息。为了满足这一需求，勒克哈特实验室目前正在对AN中的单核苷酸多态(SNPs)进行定位。冈比亚免疫信号基因，以确定马里和喀麦隆疫区自然发生的蚊子种群中恶性疟原虫感染的显著关联。在以前的出版物中，勒克哈特实验室证明，血餐中的人胰岛素以及胰岛素和胰岛素样生长因子(IIS)级联信号可以调节斯氏按蚊的疟疾寄生虫发展，斯氏按蚊是一种与蚊子关系密切的物种。冈比亚亚目。因此，IIS级联蛋白一直是这些基因分型工作的主要焦点。到目前为止，我们已经在AN中发现了大量的SNP。冈比亚类胰岛素肽(AgILP)基因，包括AgILP3中与恶性疟原虫感染显著相关的一个基因(Horton等人。2010)。自这项工作以来，我们已经发现了更多的AgILP SNPs，包括AgILP3和AgILP4中的三个被预测会改变蛋白质功能的SNPs。目前正在进行基因分型工作，以确定是否这些SNP中的任何一个或全部也与田间寄生虫感染显著相关 收集蚊子。根据人类胰岛素和恶性疟原虫感染也可以诱导斯氏疟原虫中肠ILP基因表达的数据，我们的基因分型数据表明AgILP参与了自然条件下恶性疟原虫感染的调节。基于这些观察，我们推测蚊子ILPS的产生是对寄生虫感染的反应，可能是为了放大对血源性因子或胰岛素样寄生虫因子的早期反应，以持续调节蚊子宿主对恶性疟原虫的感染。为了验证这一假说，我们将确定哪些ILP影响蚊子中肠内疟疾寄生虫的发育(特异性目标1)，哪些途径调节ILP的合成、分泌和生物活性(特异性目标2)，以及自然发生的SNP突变对ILP功能的影响(特异性目标3)。这些研究不仅将提供与自然条件下寄生虫传播有关的免疫细胞信号的关键见解，还将为操纵蚊子免疫反应以降低疟疾传播能力提供新的靶点。 与公共卫生相关：疟疾是全世界传染病死亡的主要原因之一。斯氏按蚊和冈比亚按蚊分别是印度和撒哈拉以南非洲疟疾病原体的主要媒介。由于新出现的挑战，如疟原虫的抗药性和蚊子对杀虫剂的抗药性，对新的疟疾控制战略的需求越来越大。拟议的项目将确定和描述两个主要疟疾媒介中免疫反应基因操纵的新目标，并有可能将这些发现推广到其他按蚊物种，以加强疟疾控制。

DESCRIPTION (provided by applicant): The mosquito Anopheles gambiae is the primary vector of the deadly human malaria parasite Plasmodium falciparum in sub-Saharan Africa. While many laboratory studies have focused on how the mosquito immune system responds to and destroys these parasites, there is currently little available information on whether these responses are important under natural conditions. To address this need, the Luckhart laboratory is currently mapping single nucleotide polymorphisms (SNPs) in An. gambiae immune signaling genes to identify significant associations with P. falciparum infection in naturally occurring mosquito populations in endemic areas of Mali and Cameroon. In previous publications, the Luckhart laboratory demonstrated that human insulin in the blood meal and the insulin and insulin-like growth factor signaling (IIS) cascade can regulate malaria parasite development in Anopheles stephensi, a species closely related to An. gambiae. Hence, the IIS cascade proteins have been a major focus of these genotyping efforts. Thus far, we have identified numerous SNPs in the An. gambiae insulin-like peptide (AgILP) genes, including one in AgILP3 that is significantly associated with P. falciparum infection (Horton et al. 2010). Since this work, we have identified additional AgILP SNPs, including three SNPs in AgILP3 and AgILP4 that are predicted to alter protein function. Genotyping efforts are currently underway to determine whether any or all of these SNPs are also significantly associated with parasite infection in field collected mosquitoes. In light of data that demonstrate that human insulin and infection with P. falciparum can also induce the expression of ILP genes in the A. stephensi midgut, our genotyping data suggest that the AgILPs are involved in the regulation of P. falciparum infection under natural conditions. Based on these observations, we hypothesize that mosquito ILPs are produced in response to parasite infection, perhaps to amplify an earlier response to blood-derived factors or to insulin-like parasite factors, for sustained regulation of P. falciparum infection by the mosquito host. To test this hypothesis, we will determine which ILPs influence malaria parasite development in the mosquito midgut (Specific Aim 1), which pathways regulate ILP synthesis, secretion, and bioactivity (Specific Aim 2), and the effects of naturally occurring SNP mutations on ILP function (Specific Aim 3). These studies will not only provide key insights regarding immune cells signaling that is linked to parasite transmission under natural conditions, but will also provide novel targets for manipulating the mosquito immune response to reduce malaria transmission capacity. PUBLIC HEALTH RELEVANCE: Malaria is one of the leading causes of death from infectious diseases worldwide. The mosquitoes Anopheles stephensi and Anopheles gambiae are major vectors of the causative Plasmodium agents in India and Sub-Saharan Africa, respectively. Due to emerging challenges such as drug resistance in Plasmodium and insecticide resistance in the mosquito, there is an increasing need for novel malaria control strategies. The proposed project will identify and characterize new targets for genetic manipulation of the immune response in two major malaria vectors, with the potential of extending these findings to other Anopheles species in order to enhance malaria control.