Darby Christie S, Featherston Kyah M, Lin Jingyi, Franz Alexander W E
Department of Veterinary Pathobiology, University of Missouri, Columbia, MO 65211, USA.
Insects. 2023 Jul 3;14(7):601. doi: 10.3390/insects14070601.
La Crosse virus (LACV) is circulating in the midwestern and southeastern states of the United States and can cause human encephalitis. The main vector of the virus is the eastern tree-hole mosquito, . has been also described as a natural LACV vector, while has been infected with the virus under laboratory conditions. Here, we compare the vertical transmission potential of LACV in and , with emphasis given to the ovarian infection patterns that the virus generates in both species. Both mosquito species received artificial bloodmeals containing LACV. At defined time points post-infection/bloodmeal, midguts, head tissue, and ovaries were analyzed for the presence of virus. Viral infection patterns in the ovaries were visualized via immunofluorescence confocal microscopy and immunohistopathology assays using an LACV-specific monoclonal antibody. In , LACV was confronted with midgut infection and escape barriers, which were much less pronounced in , resulting in a significantly higher prevalence of infection in the latter. Following the ingestion of a single virus-containing bloodmeal, no progeny larvae were found to be virus-infected. Regardless, females of both species showed the presence of LACV antigen in their ovariole sheaths. Furthermore, in a single female, viral antigen was associated with the nurse cells inside the primary follicles. Following the ingestion of a second non-infectious bloodmeal at 7- or 10-days post-ingestion of an LACV-containing bloodmeal, more progeny larvae of than of were virus-infected. LACV antigen was detected in the egg chambers and ovariole sheaths of both mosquito species. Traces of viral antigen were also detected in a few oocytes from . The low level of vertical transmission and the majority of the ovarian infection patterns suggested the transovum rather than transovarial transmission (TOT) of the virus in both vector species. However, based on the detection of LACV antigen in follicular tissue and oocytes, there was the potential for TOT among several females. Thus, TOT is not a general feature of LACV infection in mosquitoes. Instead, the TOT of LACV seems to be dependent on its particular interaction with the reproductive tissues of a female.
拉克罗斯病毒（LACV）在美国中西部和东南部各州传播，可引发人类脑炎。该病毒的主要传播媒介是东部树洞蚊， 也被描述为LACV的自然传播媒介，而 在实验室条件下已感染该病毒。在此，我们比较了LACV在 和 中的垂直传播潜力，重点关注该病毒在这两个物种中产生的卵巢感染模式。两种蚊子均接受了含有LACV的人工血餐。在感染/进食血餐后的特定时间点，分析中肠、头部组织和卵巢中是否存在病毒。通过免疫荧光共聚焦显微镜和使用LACV特异性单克隆抗体的免疫组织病理学检测，观察卵巢中的病毒感染模式。在 中，LACV面临中肠感染和逃逸障碍，而在 中这些障碍则不那么明显，导致后者的感染率显著更高。在摄入单一含病毒血餐后，未发现子代幼虫被病毒感染。尽管如此，两个物种的雌性蚊子卵巢鞘中均显示存在LACV抗原。此外，在一只 雌性蚊子中，病毒抗原与初级卵泡内的滋养细胞相关。在摄入含LACV血餐7天或10天后再摄入一次非感染性血餐， 感染病毒的子代幼虫比 更多。在两种蚊子的卵室和卵巢鞘中均检测到LACV抗原。在 的少数卵母细胞中也检测到了微量病毒抗原。低水平的垂直传播以及大多数卵巢感染模式表明，在这两种传播媒介物种中，病毒是经卵传递而非经卵巢传递（TOT）。然而，基于在卵泡组织和卵母细胞中检测到LACV抗原，部分 雌性蚊子存在经卵巢传递的可能性。因此，经卵巢传递并非蚊子感染LACV的普遍特征。相反，LACV的经卵巢传递似乎取决于其与雌性生殖组织的特定相互作用。
