Department of Vector Biology, Centre for Neglected Tropical Disease, Liverpool School of Tropical Medicinegrid.48004.38, Liverpool, United Kingdom.
Department Tropical Disease Biology, Centre for Neglected Tropical Disease, Liverpool School of Tropical Medicinegrid.48004.38, Liverpool, United Kingdom.
Appl Environ Microbiol. 2022 Sep 22;88(18):e0106222. doi: 10.1128/aem.01062-22. Epub 2022 Aug 29.
Cell fusing agent virus (CFAV) is an insect-specific flavivirus (ISF) found in Aedes aegypti mosquitoes. ISFs have demonstrated the ability to modulate the infection or transmission of arboviruses such as dengue, West Nile, and Zika viruses. It is thought that vertical transmission is the main route for ISF maintenance in nature. This has been observed with CFAV, but there is evidence of horizontal and venereal transmission in other ISFs. Understanding the route of transmission can inform strategies to spread ISFs to vector populations as a method of controlling pathogenic arboviruses. We crossed individually reared male and female mosquitoes from both a naturally occurring CFAV-positive Ae. aegypti colony and its negative counterpart to provide information on maternal, paternal, and horizontal transmission. RT-PCR was used to detect CFAV in individual female pupal exuviae and was 89% sensitive, but only 42% in male pupal exuviae. This is a possible way to screen individuals for infection without destroying the adults. Female-to-male horizontal transmission was not observed during this study. However, there was a 31% transmission rate from mating pairs of CFAV-positive males to negative female mosquitoes. Maternal vertical transmission was observed with a filial infection rate of 93%. The rate of paternal transmission was 85% when the female remained negative, 61% when the female acquired CFAV horizontally, and 76% overall. Maternal and paternal transmission of CFAV could allow the introduction of this virus into wild Ae. aegypti populations through male or female mosquito releases, and thus provides a potential strategy for ISF-derived arbovirus control. Insect-specific flaviviruses (ISFs), are a group of nonpathogenic flaviviruses that only infect insects. ISFs can have a high prevalence in mosquito populations, but their transmission routes are not well understood. The results of this study confirm maternal transmission of cell fusing agent virus (CFAV) and demonstrate that paternal transmission is also highly efficient. Horizontal transmission of CFAV was also observed, aided by evaluation of the pupal infection status before mating with an infected individual. This technique of detecting infection in discarded pupae exuviae has not been evaluated previously and will be a useful tool for others in the field of studying viral transmission in mosquitoes. Identifying these routes of transmission provides information about how CFAV could be maintained in wild populations of mosquitoes and can aid future studies focusing on interactions of CFAV with their hosts and other viruses that infect mosquitoes.
细胞融合剂病毒（CFAV）是一种存在于埃及伊蚊中的昆虫特异性黄病毒（ISF）。ISF 已被证明能够调节登革热、西尼罗河和寨卡病毒等虫媒病毒的感染或传播。人们认为垂直传播是 ISF 在自然界中维持的主要途径。这在 CFAV 中已经观察到，但也有证据表明其他 ISF 存在水平和性传播。了解传播途径可以为将 ISF 传播到媒介种群作为控制致病性虫媒病毒的方法提供信息。我们分别对来自自然发生的 CFAV 阳性埃及伊蚊种群及其阴性对照的雄性和雌性蚊子进行了交叉饲养，以提供有关母系、父系和水平传播的信息。使用 RT-PCR 检测个体雌性蛹蜕的 CFAV，其敏感性为 89%，但在雄性蛹蜕中仅为 42%。这是一种在不破坏成虫的情况下筛选感染个体的可能方法。在本研究中，没有观察到雌性到雄性的水平传播。然而，阳性雄性与阴性雌性蚊子交配的传播率为 31%。观察到母系垂直传播，亲代感染率为 93%。当雌性仍为阴性时，父系传播率为 85%，当雌性通过水平途径获得 CFAV 时，传播率为 61%，总体传播率为 76%。CFAV 的母系和父系传播可以通过释放雄性或雌性蚊子将这种病毒引入野生埃及伊蚊种群，因此为利用 ISF 衍生的虫媒病毒控制提供了一种潜在策略。昆虫特异性黄病毒（ISF）是一组非致病性黄病毒，仅感染昆虫。ISF 在蚊子种群中的流行率可能很高，但它们的传播途径尚不清楚。本研究的结果证实了细胞融合剂病毒（CFAV）的母系传播，并表明父系传播也非常有效。还观察到 CFAV 的水平传播，这得益于在与感染个体交配之前评估蛹的感染状态。这种检测丢弃蛹蜕中感染的技术以前尚未得到评估，将成为该领域研究蚊子中病毒传播的其他人的有用工具。确定这些传播途径提供了有关 CFAV 如何在野生蚊子种群中维持的信息，并可以帮助未来的研究集中于 CFAV 与其宿主和感染蚊子的其他病毒的相互作用。
