Effects of Arboviral Population Diversity on Transmission

虫媒病毒种群多样性对传播的影响

• 批准号: 8631391
• 负责人: Naomi Lynne Forrester
• 金额: $ 37.55万
• 依托单位: UNIVERSITY OF TEXAS MED BR GALVESTON
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-11-18 至 2018-10-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8631391
• 关键词: Aedes; Arboviruses; Area; Arthropod Vectors; Attenuated; Bacteria; Cells; Chikungunya virus; Communicable Diseases; Complex; Culex (Genus); Culicidae; Data; Dengue; Disease; Disease Outbreaks; Ecology; Engineering; Environment; Epidemic; Event; Evolution; Exhibits; Extinction (Psychology); Frequencies; Genetic Drift; Genetic Variation; Genome; Geographic Locations; Goals; Human; Incidence; Infection; Insect Viruses; Laboratories; Lead; Licensing; Mediating; Mexico; Midgut; Minority; Modeling; Mutate; Mutation; Natural Selections; Natural regeneration; Polymerase; Population; Population Genetics; Protocols documentation; Public Health; RNA Viruses; Recording of previous events; Research; Research Proposals; Rodent; Salivary Glands; Sampling; Severities; Technology; Testing; Ticks; Translating; Vaccines; Variant; Venezuelan Equine Encephalitis Virus; Viral; Virus; West Nile virus; Wolbachia; Work; chikungunya; enzootic; experience; fitness; genetic manipulation; genetic selection; human morbidity; human mortality; interest; next generation sequencing; particle; pathogen; public health relevance; response; transmission process; vector; vector mosquito; viral RNA

This research proposal looks at the importance of viral diversity on transmission and evolution. Viruses exist not as clonal populations but as 'swarms' of variants with mutations along the genome. Variation has not been characterised in arboviruses (arthropod-borne viruses), which require infection of a vertebrate host and a vector (such as a mosquito or tick). During infection of the mosquito there are several anatomical barriers that reduce the number of viral particles, thus a bottleneck is imposed on the virus. It is hypothesised that, upon infection of the mosquito vector, the amount of variation decreases, leading to a decreased rate of evolution in the arboviruses as compared to viruses with a single host. The rate of evolution is important to understand viral ecology and emergence. Venezuelan equine encephalitis virus (VEEV) and two natural mosquito vectors will be used to model viral variation present in wild-type transmission, and the impact that mosquito infection has on viral diversity. VEEV is of interest because it is both an important, naturally emerging virus and a potential bioweapon with no licensed vaccine or therapy. The virus circulates in Mexico and has caused outbreaks in equids and humans in the U.S. Viral diversity will be investigated using 3 specific aims. First, the bottleneck profile of the epidemic vector Psorophora confinnis will be determined compared to the bottleneck profile already determined for the enzootic vector Culex taeniopus. Secondly, the profile of intra-host variation of VEEV subtypes IE and IC will be determined upon infection of the mosquito vectors C. taeniopus and Aedes taeniorhynchus and an appropriate rodent host, individually and as part of a transmission cycle. The effect of the anatomical mosquito bottlenecks on viral diversity will be investigated using an established protocol to initiate a laboratory transmission cycle that approximates to that occurring naturally. The levels of diversity will be determined using Next Generation Sequencing technology to determine the minority populations present throughout the transmission cycle. This decrease in diversity may lead to a reduction in fitness due to stochastic effects. The level of drift caused by this decrease in diversity will be tested via an experimental transmission cycle. Thirdly, the change in the ability of the virus to complete a transmission cycle when the polymerase fidelity is increased by genetic manipulation will be examined. It is hypothesized that viral variation aids in viral survival therefore viruses mutated to exhibit high-fidelity in their replication will be used in experimental infections. It is expected that viral survival will decrease. The results of this project will enhance our understanding of arboviral population genetic dynamics occurring in the mosquito vector as well as determine the degree to which natural selection and genetic drift influence the persistence and emergence of new arboviruses. The results will translate to other emerging arboviruses such as dengue, West Nile and chikungunya, as well as provide the data to generate effective models of arbovirus emergence.

这项研究计划着眼于病毒多样性对传播和进化的重要性。病毒存在 不是作为克隆种群，而是作为沿着基因组沿着突变的变体的“成群”。变化尚未 以虫媒病毒（节肢动物传播的病毒）为特征，其需要感染脊椎动物宿主和 媒介（如蚊子或蜱）。在蚊子感染期间，有几个解剖屏障， 减少病毒颗粒的数量，从而对病毒施加瓶颈。据推测，在 当蚊子媒介感染时，变异量减少，导致进化速度下降， 虫媒病毒与单一宿主的病毒相比。进化的速度对于理解病毒 生态学和涌现委内瑞拉马脑炎病毒（VEEV）和两种天然蚊子载体将 可用于模拟野生型传播中存在的病毒变异，以及蚊子感染对 关于病毒多样性。VEEV之所以令人感兴趣，是因为它既是一种重要的自然出现的病毒， 没有许可的疫苗或疗法的生化武器该病毒在墨西哥传播，并在 将使用3个特定目标研究美国的马和人类的病毒多样性。一、瓶颈 将与瓶颈概况进行比较，确定流行病媒介Psorophora confinnis的概况 已经确定的地方病媒介带尾库蚊。其次，分析了寄主内变异的概况， VEEV亚型IE和IC将在蚊子载体C感染后确定。带足伊蚊和伊蚊 带喙线虫和适当的啮齿类宿主，单独和作为传播周期的一部分。的影响 将使用已建立的方案研究蚊子对病毒多样性的解剖学瓶颈， 启动一个实验室传播周期，近似于自然发生的传播周期。多样性水平将 使用下一代测序技术确定存在的少数群体 整个传输周期。这种多样性的减少可能会导致适应度的降低， 随机效应由多样性减少引起的漂移水平将通过一个实验来测试。 传输周期第三，病毒完成一个传播周期的能力发生变化， 将检查通过遗传操作增加聚合酶保真度。假设病毒变异 有助于病毒存活，因此，突变为在其复制中表现出高保真度的病毒将用于 实验性感染预计病毒存活率将降低。该项目的成果将提高 我们对蚊子媒介中虫媒病毒种群遗传动力学的理解， 确定自然选择和遗传漂变影响持续和出现的程度， 新虫媒病毒这些结果将转化为其他新兴的虫媒病毒，如登革热，西尼罗河病毒和 基孔肯雅热，以及提供数据，以产生虫媒病毒出现的有效模型。