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Abstract：
BACKGROUND: Vertical transmission (VT) of arboviruses (arthropod-borne viruses) can serve as an essential link in the transmission cycle during adverse environmental conditions. The extent of VT among mosquito-borne arboviruses can vary significantly among different virus families and even among different viruses within the same genus. For example, orthobunyaviruses exhibit a higher VT rate than orthoflaviviruses and alphaviruses. Mosquitoes are also the natural hosts of a large number of insect-specific viruses (ISV) that belong to several virus families, including Bunyaviridae, Flaviviridae, and Togaviridae. Cell fusing agent virus (CFAV), an insect-specific orthoflavivirus, displays higher VT rates than other dual-host orthoflaviviruses, such as Zika and dengue viruses. High VT rates require establishment of stabilized infections in the germinal tissues of female vectors. To delve deeper into understanding the mechanisms governing these differences in VT rates and the establishment of stabilized infections, the ovary infection patterns and VT of Zika virus (ZIKV) and CFAV were compared.
METHODS: Laboratory colonized Aedes aegypti females were infected with either ZIKV or CFAV by intrathoracic injection. Ovary infection patterns were monitored by in situ hybridization using virus-specific probes, and VT was determined by detecting the presence of the virus among the progeny, using a reverse-transcription quantitative polymerase chain reaction (PCR) assay.
RESULTS: Both ZIKV and CFAV infect mosquito ovaries after intrathoracic injection. Infections then become widespread following a non-infectious blood meal. VT rates of ZIKV are similar to previously reported results (3.33%). CFAV, on the contrary transmits vertically very rarely. VT was not observed in the first gonotrophic cycle following intrathoracic injection, and only rarely in the second gonotrophic cycle. VT of CFAV is mosquito population independent, since similar results were obtained with Aedes aegypti collected from two different geographic locations.
CONCLUSIONS: Although CFAV infects mosquito ovaries, the occurrence of VT remains infrequent in artificially infected Ae. aegypti, despite the observation of high VT rates in field-collected mosquitoes. These results suggest that infections of insect-specific viruses are stabilized in mosquitoes by some as yet unidentified mechanisms.
METHODS: Laboratory colonized Aedes aegypti females were infected with either ZIKV or CFAV by intrathoracic injection. Ovary infection patterns were monitored by in situ hybridization using virus-specific probes, and VT was determined by detecting the presence of the virus among the progeny, using a reverse-transcription quantitative polymerase chain reaction (PCR) assay.
RESULTS: Both ZIKV and CFAV infect mosquito ovaries after intrathoracic injection. Infections then become widespread following a non-infectious blood meal. VT rates of ZIKV are similar to previously reported results (3.33%). CFAV, on the contrary transmits vertically very rarely. VT was not observed in the first gonotrophic cycle following intrathoracic injection, and only rarely in the second gonotrophic cycle. VT of CFAV is mosquito population independent, since similar results were obtained with Aedes aegypti collected from two different geographic locations.
CONCLUSIONS: Although CFAV infects mosquito ovaries, the occurrence of VT remains infrequent in artificially infected Ae. aegypti, despite the observation of high VT rates in field-collected mosquitoes. These results suggest that infections of insect-specific viruses are stabilized in mosquitoes by some as yet unidentified mechanisms.
摘要：
背景：虫媒病毒（节肢动物传播的病毒）的垂直传播（VT）可以在不利的环境条件下充当传播周期中的必要环节。蚊媒虫媒病毒中的VT程度在不同病毒家族之间甚至在同一属内的不同病毒之间可以显着变化。例如,正双甲病毒比正双甲病毒和甲病毒表现出更高的VT率。蚊子也是大量昆虫特异性病毒(ISV)的天然宿主,包括Bunyaviridae,黄病毒科,和Togaviridae。细胞融合剂病毒(CFAV),一种昆虫特异性正黄病毒,显示比其他双宿主正黄病毒更高的VT率，例如寨卡病毒和登革热病毒。高VT率需要在女性载体的生发组织中建立稳定的感染。为了更深入地了解控制室性心动过速率差异和稳定感染建立的机制，比较了寨卡病毒（ZIKV）和CFAV的卵巢感染模式和VT。
方法：实验室定植的埃及伊蚊雌性通过胸腔内注射感染ZIKV或CFAV。使用病毒特异性探针通过原位杂交监测卵巢感染模式，VT是通过检测子代中病毒的存在来确定的，使用逆转录定量聚合酶链反应（PCR）测定。
结果：胸腔内注射后，ZIKV和CFAV均感染蚊子卵巢。然后感染在非传染性血餐后变得普遍。ZIKV的VT率与先前报道的结果相似(3.33%)。CFAV,相反，垂直传播很少。在胸腔内注射后的第一个促性腺激素周期中未观察到VT，在第二个促性腺激素周期中很少见。CFAV的VT与蚊子种群无关，因为从两个不同的地理位置收集的埃及伊蚊获得了类似的结果。
结论：尽管CFAV会感染蚊子卵巢，在人工感染的Ae中，VT的发生仍然很少。埃及伊蚊,尽管在野外收集的蚊子中观察到高VT率。这些结果表明，昆虫特异性病毒的感染通过一些尚未确定的机制在蚊子中稳定。
方法：实验室定植的埃及伊蚊雌性通过胸腔内注射感染ZIKV或CFAV。使用病毒特异性探针通过原位杂交监测卵巢感染模式，VT是通过检测子代中病毒的存在来确定的，使用逆转录定量聚合酶链反应（PCR）测定。
结果：胸腔内注射后，ZIKV和CFAV均感染蚊子卵巢。然后感染在非传染性血餐后变得普遍。ZIKV的VT率与先前报道的结果相似(3.33%)。CFAV,相反，垂直传播很少。在胸腔内注射后的第一个促性腺激素周期中未观察到VT，在第二个促性腺激素周期中很少见。CFAV的VT与蚊子种群无关，因为从两个不同的地理位置收集的埃及伊蚊获得了类似的结果。
结论：尽管CFAV会感染蚊子卵巢，在人工感染的Ae中，VT的发生仍然很少。埃及伊蚊,尽管在野外收集的蚊子中观察到高VT率。这些结果表明，昆虫特异性病毒的感染通过一些尚未确定的机制在蚊子中稳定。
