SERINE PROTEASES AND IMMUNITY IN ANOPHELES GAMBIAE

疟疾是一种由疟原虫属寄生原生动物引起的疾病，由蚊子传播给人类。每年有数亿人感染这种病菌，造成200 - 300万人死亡，其中大多数是幼儿。这一问题在非洲最为严重，而且由于寄生虫对过去用于预防和控制的廉价药物的耐药性日益增强，这一问题正在恶化。第二个重要的控制战略，即通过使用杀虫剂减少蚊子种群，也因杀虫剂抗药性、成本增加和训练有素人员的流失而受到威胁。一个新的研究目标是蚊子和寄生虫之间的相互作用。本文提出的这项研究的长期目标是了解蚊子和疟疾寄生虫不相容的分子基础，因为这可能提出通过对媒介蚊子进行遗传或化学操作来增强导致不相容的机制的方法。这项拟议的研究将集中在描述蚊子体液免疫反应中涉及的蛋白质和基因，这种反应可能导致寄生虫死亡。特别是丝氨酸蛋白酶在黑素包封和抗菌反应两种寄生虫杀灭机制的产生中是重要的酶。在非洲疟疾媒介冈比亚按蚊（Anopheles gambiae）中，三种丝氨酸蛋白酶基因AgSp14D1、AgSp14D2和AgSp14A在细菌注射或疟疾寄生虫感染后表现出转录水平的变化。这些分子将被表征并测试是否参与体内和体外对寄生虫的免疫反应。此外，将对激活丝氨酸蛋白酶的酚氧化酶原进行生化纯化，并对其进行克隆和鉴定。最后，几种冈比亚芽孢杆菌丝氨酸蛋白酶表现出与其他参与免疫反应的酶相似的结构域结构，将在mRNA和蛋白质水平上进行表征。

Malaria, a disease caused by parasitic protozoans in the genus Plasmodium, is transmitted by mosquitoes to humans. Each year, hundreds of millions of people are infected with this organism and 2-3 million fatalities result, mostly in young children. The problem is most severe in Africa, and is now worsening because of the increasing resistance of parasites to the inexpensive drugs used for prevention and control in the past. A second important strategy for control, reducing mosquito populations through insecticide use, is also threatened because of insecticide resistance, increasing costs and loss of trained personnel. A new target for research has been the interaction between the mosquito and the parasite. The long-term goal of the research presented here is to understand the molecular basis for incompatibility between mosquitoes and malaria parasites because this may suggest ways to enhance mechanisms that cause incompatibility through genetic or chemical manipulation of vector mosquitoes. The proposed research will focus on characterizing proteins and genes that are involved in the mosquito's humoral immune responses, which can lead to the death of parasites. In particular, serine proteases are important enzymes in generation of two parasite-killing mechanisms, melanotic encapsulation and the antimicrobial response. In the African malaria vector, Anopheles gambiae, three serine protease genes, AgSp14D1, AgSp14D2, and AgSp14A, show changes in transcript levels after bacterial injections or infection with malaria parasites. These molecules will be characterized and tested for involvement in immune responses against parasites in vitro and in vivo. In addition, prophenoloxidase activating serine proteases, which are important in triggering parasite melanization, will be biochemically purified and then cloned and characterized. Finally, several A. gambiae serine proteases that exhibit domain structures similar to other enzymes involved in immune responses will be characterized at the mRNA and protein levels.