Passerine filariasis and West Nile virus transmission

雀形丝虫病和西尼罗河病毒传播

• 批准号: 8493341
• 负责人: Jefferson Archer Vaughan
• 金额: $ 20.7万
• 依托单位: UNIVERSITY OF NORTH DAKOTA
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-04-22 至 2015-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8493341
• 关键词: Acceleration; Accounting; Address; Adopted; Affect; Arboviruses; Area; Biological Models; Birds; Blood; Blood-Borne Pathogens; Body cavities; Categories; Chronic; Culex pipiens; Culicidae; Development; Dose; Epidemiology; Filariasis; Health; Heterogeneity; High Prevalence; Immune; Immunity; Individual; Infection; Ingestion; Knowledge; Laboratory Study; Lead; Low Prevalence; Maintenance; Mediating; Microfilaria; Midgut; Modeling; Nature; North America; Outcome; Parasites; Population; Prevalence; Refractory; Research Personnel; Robin bird; Role; Songbirds; System; Testing; Time; Ursidae Family; Vertebrates; Viral; Virus; Virus Diseases; West Nile virus; body cavity; enzootic; epizootic; feeding; field study; parasitism; pathogen; public health relevance; research study; survivorship; transmission process; vector; vector mosquito; vector transmission

DESCRIPTION (provided by applicant): In nature, vertebrate hosts of arboviruses often harbor parasites, including microfilariae. Laboratory studies have shown that concurrent ingestion of microfilariae and arboviruses by mosquitoes can result in significantly more efficient transmission of the arbovirus than when the same dose of arbovirus is ingested alone. That is because when microfilariae are ingested, they can penetrate the mosquito midgut and allow immediate dissemination of virus into the mosquito body cavity. This increases and accelerates viral infectivity of mosquitoes and can have 2 important epidemiological consequences. First, mosquito species that are normally refractory to viral infection because of midgut barriers to vira infectivity may now develop infections. This can increase the number and importance of secondary vector species involved in a virus transmission cycle. Second, microfilarial enhancement can accelerate viral development within the mosquito, shortening the time required for mosquitoes to become infectious (=extrinsic incubation period [EIP]). Small reductions in EIP can lead to large increases in vectorial capacity. This phenomenon is called "microfilarial enhancement of arboviral transmission" and has been validated using several artificially contrived model systems. However, microfilarial enhancement has never been tested using a naturally-occurring enzootic arboviral transmission system. That is what this proposal intends to do. In North America, songbirds harbor a diversity of filarial parasites, often at very high prevalence. Songbirds are also important for the enzootic maintenance of certain arboviruses, such as West Nile virus (WNV). The hypothesis of this proposal is that the microfilarial infections in songbirds may enhance WNV transmission by the enzootic mosquito vector, Culex pipiens. To test the hypothesis, infection outcomes will be compared between mosquitoes fed on dually infected birds (i.e., WNV plus microfilariae) versus singly infected birds (i.e., WNV only). The experiments will quantify the effect that dual infections have on the subsequent 1) viral dissemination rate within mosquitoes, 2) rate of WNV transmission by mosquitoes, 3) extrinsic incubation period of WNV within mosquitoes, and 4) daily survivorship of mosquitoes. The results of these studies will determine whether dually infected songbirds enhance virus transmission to mosquitoes compared with that of singly infected songbirds. If so, this opens the possibility that within a given population of WNV-competent bird species, those individuals with active microfilarial infections may constitute a subpopulation of potential "super transmitters". Significance. Without a fuller understanding of the potential role of microfilarial enhancement in naturally occurring systems, cryptic, potentially important amplifying hosts and vectors may be overlooked and our understanding of enzootic transmission of arboviruses may be incomplete.

描述（由申请人提供）：在自然界中，脊椎动物的脊椎动物宿主通常具有包括微丝菌在内的寄生虫。实验室研究表明，蚊子同时摄入微丝菌和arbovirus可以使人明显更有效 与单独摄入相同剂量的arbovirus相比，arbovirus的传播。那是因为当摄入微丝菌时，它们可以穿透蚊子中肠并立即将病毒传播到蚊子体腔中。这增加并加速了蚊子的病毒感染性，并可能产生2种重要的流行病学后果。首先，由于中肠屏障的Vira感染性，通常对病毒感染难治的蚊子物种现在可能发展出感染。这可以增加涉及病毒传播周期中次要载体物种的数量和重要性。其次，微移动性增强可以加速蚊子内的病毒发育，从而缩短了蚊子变得具有传染性所需的时间（=外部孵化期[EIP]）。 EIP的少量减少会导致矢量能力大大增加。该现象称为“弧病毒传播的微芯片增强”，并已使用几种人为人为的模型系统进行了验证。但是，从未使用自然存在的Enzootic arboviral传输系统测试过微丝增强。这就是该提案打算做的。在北美，鸣鸟带有各种各样的丝状寄生虫，通常很高。鸣禽对于某些arboviruses（例如西尼罗河病毒（WNV））的enzootic维持也很重要。该提议的假设是，鸣禽中的微脊髓感染可能会增强enzootic蚊子载体Culex Pipiens的WNV传播。为了检验该假设，将在双重感染鸟类（即WNV Plus Microfilariae）与单一感染的鸟类中进行比较感染结果 （即仅WNV）。实验将量化双重感染对随后的影响1）蚊子内的病毒传播速率，2）蚊子的WNV传播速率，3）蚊子内WNV的外在孵育期，以及4）蚊子的每日生存。这些研究的结果将确定与单一感染的鸣禽相比，双重感染的鸣禽是否可以增强对蚊子的病毒传播。如果是这样，这将打开一个可能性的可能性，在给定的WNV能力鸟类物种中，那些活跃的微虫感染的个体可能构成潜在的亚群体“超级人群” 发射器”。重要的是。在天然发生的系统中，微妙增强的潜在作用的潜在作用，可能会忽略神秘的，潜在的放大宿主和向量的潜在作用，并且我们对arbovirus的Enzootic传播的理解可能是不完整的。