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

总结 基孔肯雅病毒（CHIKV）自印度洋地区传播以来已成为全球性问题， 环绕地球仪。2014年，这种扩张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流行病。作为一个公共卫生问题，这种疾病的成本是巨大的， 因为感染后容易出现慢性关节炎如果没有疫苗或药物治疗， 控制是限制疾病的唯一解决办法。CHIKV由两种蚊子传播， 白纹伊蚊和埃及伊蚊，它们已经扩散到大部分温带和热带地区， 世界因为它是非常遥远的关系，其更普遍的表亲，登革热病毒（DENV），蚊子 种群几乎没有机会进化出对CHIKV的抗性。由于DENV和CHIKV都引起 蚊子的适应性降低，它们有可能在种群中起到选择性的作用， 它们发生了。CHIKV扩大影响的潜力令人担忧，因为它似乎能够更好地感染 蚊子比DENV。在目标1中，我们采用实验进化方法来理解相对的 与DENV相比，蚊子进化出对CHIKV的抗性的潜力。在进化的线条中，我们将使用 全基因组关联以鉴定支持病毒抗性的候选SNP/基因。使用高效 专门针对Ae.我们就可以测试 最佳候选基因在目标2中，我们探索了一套遗传学的功能重要性， 在CHIKV包膜蛋白编码基因（E2）中普遍存在的变体。E2介导进入 蚊子组织，基因的变异可以影响病媒的传播能力。为了实现这些目标，我们 将产生新的工具，并在新的背景下应用新兴工具，包括使用改进的 荧光报告病毒在蚊子体内而不是体外以及“Vectorchip”载体的适应 与CHIKV和Ae.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性进化的帮助下， 传播可能随时间发展到较低水平，（ii）潜在的抗CHIKV和共享的抗CHIKV病毒的列表， 在遗传修饰方法中靶向的CHIKV和DENV蚊子基因，以及（iii）理解 CHIKV基因组中的循环E2变体如何影响蚊子的感染性和全球景观 CHIKV流行病学

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.