1Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado.
2Department of Biochemistry and Molecular Biology, College of Agriculture, Biotechnology and Natural Resources, University of Nevada, Reno, Nevada.
Am J Trop Med Hyg. 2020 Aug;103(2):869-875. doi: 10.4269/ajtmh.20-0143. Epub 2020 May 14.
Chikungunya virus (CHIKV) and Zika virus (ZIKV) are arthropod-borne viruses transmitted mainly by mosquitoes. These viruses have become endemic in large parts of North, Central, and South America. Arboviruses persistently infect mosquitoes throughout their life span and become infectious (i.e., expectorate infectious virus in saliva) after a period of time called the extrinsic incubation period (EIP). The duration of this infectiousness, however, is not well characterized. This is an important shortcoming because many epidemiological models assume that mosquitoes continue to be infectious for the duration of their life span. To define the duration of infectiousness for CHIKV and ZIKV, mosquitoes were infected orally with these viruses. Every 2 days, legs/wings, midguts, salivary glands, and saliva were collected from 30 to 60 mosquitoes and viral load measured. In CHIKV-infected mosquitoes, infectious virus in saliva peaked early (2-4 dpi), and then decreased rapidly and was rarely observed after 10 dpi. Viral RNA in infected tissues also decreased after the initial peak (4-8 dpi) but did so much less drastically. In ZIKV-infected mosquitoes, the infectious virus in saliva peaked at 12-14 dpi and dropped off only slightly after 14 dpi. In infected tissues, viral RNA increased early during infection, and then plateaued after 6-10 days. Our findings suggest that significant variation exists in the duration of the infectious period for arboviruses that is in part influenced by virus clearance from expectorated saliva.
基孔肯雅病毒（CHIKV）和寨卡病毒（ZIKV）是主要通过蚊子传播的虫媒病毒。这些病毒已在北美、中美和南美大部分地区流行。虫媒病毒在蚊子的整个生命周期内持续感染蚊子，并在一段时间后（即外在潜伏期，EIP）变得具有感染性（即从唾液中排出感染性病毒）。然而，这种传染性的持续时间并没有很好地描述。这是一个重要的缺点，因为许多流行病学模型假设蚊子在其整个生命周期内都具有传染性。为了确定 CHIKV 和 ZIKV 的传染性持续时间，用这些病毒经口感染蚊子。每隔 2 天，从 30 到 60 只蚊子中收集腿/翅膀、中肠、唾液腺和唾液，并测量病毒载量。在 CHIKV 感染的蚊子中，唾液中的感染性病毒很早就达到峰值（2-4dpi），然后迅速下降，在 10dpi 后很少观察到。感染组织中的病毒 RNA 也在初始峰值后（4-8dpi）下降，但下降幅度要小得多。在 ZIKV 感染的蚊子中，唾液中的感染性病毒在 12-14dpi 达到峰值，在 14dpi 后仅略有下降。在感染组织中，病毒 RNA 在感染早期增加，然后在 6-10 天后达到平台期。我们的研究结果表明，虫媒病毒的传染性持续时间存在显著差异，部分原因是从唾液中清除的病毒。
