Exploring the coevolutionary potential of chikungunya virus and its Aedes mosquito vectors

摘要 基孔肯雅病毒(CHIKV)自印度洋地区传播以来，已成为一个全球性问题， 在全球各地。2014年，这一扩大包括拉丁美洲和加勒比地区的一次重大疫情 这导致了几个国家的地方性流行。作为一个公共卫生问题，这种疾病的代价是巨大的， 考虑到感染后往往会出现慢性关节炎。如果没有疫苗或药物治疗，媒介 控制是限制这种疾病的唯一解决方案。寨卡病毒是由两种蚊子传播的，伊蚊 白纹伊蚊和埃及伊蚊，它们已经蔓延到中国的大部分温带和热带地区 整个世界。因为它与其更常见的表亲登革热病毒(DENV)、蚊子有很远的亲缘关系 种群几乎没有机会进化出对CHIKV的抵抗力。由于DENV和CHIKV都引起 蚊子适合度的降低，它们有可能成为蚊子种群中的选择性力量 它们是会发生的。鉴于CHIKV似乎更有能力感染，其扩大影响的潜力令人担忧 蚊子比DENV。在目标1中，我们采用实验进化的方法来理解相对的 与DENV相比，蚊子进化出对CHIKV的抵抗力的可能性。在进化的品系中，我们将使用 全基因组关联，以确定支撑病毒抗性的候选SNPs/基因。使用高效 CRISPR-Cas9方法是专门为Ae开发的。埃及人，然后我们可以测试功能参与 最重要的抗性候选基因。在目标2中，我们探索了一套基因的功能重要性 全球存在于CHIKV包膜蛋白编码基因(E2)中的变体。雌激素2调节进入 蚊子组织，该基因的变异会影响媒介的传播性。为了实现这些目标，我们 将生成新工具并在新环境中应用新兴工具，包括使用改进的 蚊体内而非体外的荧光报告病毒及其载体的适应性 适用于CHIKV和AE的能力体系。白纹伊蚊。我们将解决的关键知识差距 是(I)是否在蚊子遗传多样性和抗药性进化的帮助下 传播可能会随着时间的推移演变到较低的水平，(Ii)潜在的抗-CHIKV和共享的抗-CHIKV的清单 在基因改造方法中针对CHIKV和DENV蚊子基因，以及(Iii)了解 CHIKV基因组中循环的E2变异如何影响蚊子的感染性和全球格局 奇卡病毒流行病学的研究。

SUMMARY Chikungunya virus (CHIKV) has become a global problem since it spread from the Indian Ocean region, around the globe. In 2014, this expansion included a major outbreak in Latin America and the Caribbean that has led to endemicity in several countries. The cost of the disease as a public health issue is substantial, given the chronic arthritis that tends to arise post-infection. Without a vaccine or drug treatment, vector control is the only solution for limiting the disease. CHIKV is transmitted by two species of mosquito, Aedes albopictus and Aedes aegypti, which have spread to inhabit much of the temperate and tropical regions of the world. Because it is very distantly related to its more ubiquitous cousin, dengue virus (DENV), mosquito populations have had little opportunity to evolve resistance to CHIKV. Since both DENV and CHIKV cause fitness reductions in mosquitoes, they have the potential to act as a selective force in populations where they occur. CHIKV’s potential for expanded impact is concerning, given that it appears better able to infect mosquitoes than DENV. In Aim 1, we take an experimental evolution approach to understand the relative potential for mosquitoes to evolve resistance to CHIKV compared to DENV. In the evolved lines we will use genome-wide association to identify candidate SNPs/genes that underpin virus resistance. Using efficient CRISPR-Cas9 methods developed specifically for Ae. aegypti, we can then test the functional involvement of top candidate genes in resistance. In Aim 2, we explore the functional importance of the suite of genetic variants that exist globally in a CHIKV envelope protein-encoding gene (E2). E2 mediates entry into mosquito tissues, and variation in the gene can affect vector transmissibility. In completing these aims, we will generate new tools and apply emerging tools in a new context including the use of improved fluorescent reporter viruses in mosquitoes rather than in vitro and the adaptation of the ‘Vectorchip’ vector competence system for use with CHIKV and Ae. albopictus. The key knowledge gaps we will address are (i) whether with the assistance of mosquito genetic diversity and resistance evolution if CHIKV transmission is likely to evolve to lower levels with time, (ii) a list of potential anti-CHIKV and shared anti- CHIKV and DENV mosquito genes to target in genetic modification approaches, and (iii) an understanding of how circulating E2 variants in CHIKV genome may shape mosquito infectivity and the global landscape of CHIKV epidemiology.