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恶性疟原虫的主要传播媒介。虽然许多实验室研究都集中在蚊子的免疫系统如何响应并摧毁这些寄生虫，但目前几乎没有关于这些反应在自然条件下是否重要的信息。为了满足这一需求，Luckhart实验室目前正在绘制An中的单核苷酸多态性（SNP）。冈比亚免疫信号基因，以确定与恶性疟原虫感染在马里和喀麦隆流行地区的自然发生的蚊子种群的显着关联。在以前的出版物中，Luckhart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信号传导（IIS）级联可以调节斯氏按蚊（Anopheles stephensi）中疟疾寄生虫的发育，斯氏按蚊是一种与An密切相关的物种。冈比亚。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中鉴定了许多SNP。冈比亚胰岛素样肽（AgILP）基因，包括AgILP 3中与恶性疟原虫感染显著相关的基因（Horton et al. 2010）。自这项工作以来，我们已经确定了其他AgILP SNP，包括AgILP3和AgILP4中的三个SNP，预计会改变蛋白质功能。基因分型工作目前正在进行，以确定是否任何或所有这些SNP也显着相关的寄生虫感染在外地 收集蚊子。根据证明人胰岛素和恶性疟原虫感染也可以诱导A. stephensi中肠，我们的基因分型数据表明，AgILP参与调节恶性疟原虫感染在自然条件下。基于这些观察结果，我们假设蚊子ILP是响应寄生虫感染而产生的，可能是为了放大对血液衍生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。为了验证这一假设，我们将确定哪些ILP影响疟疾寄生虫在蚊子中肠的发育（具体目标1），哪些途径调节ILP的合成，分泌和生物活性（具体目标2），以及天然存在的SNP突变对ILP功能的影响（具体目标3）。这些研究不仅将提供关于与自然条件下寄生虫传播有关的免疫细胞信号传导的关键见解，而且还将提供操纵蚊子免疫反应以降低疟疾传播能力的新靶点。 公共卫生相关性：疟疾是全球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的主要疟原虫传播媒介。由于新出现的挑战，如疟原虫的耐药性和蚊子的杀虫剂耐药性，越来越需要新的疟疾控制策略。拟议的项目将确定和描述两种主要疟疾病媒免疫反应遗传操纵的新目标，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.