Styer Linda M, Bernard Kristen A, Kramer Laura D
Arbovirus Laboratories, Wadsworth Center, New York State Department of Health, Slingerlands, New York 12159, USA.
Am J Trop Med Hyg. 2006 Aug;75(2):337-45.
Mosquito transmission of arboviruses potentially affects the course of viral infection in the vertebrate host. Studies were performed to determine if viral infection differed in chickens infected with West Nile virus (WNV) by mosquito bite or needle inoculation. Mosquito-infected chickens exhibited levels of viremia and viral shedding that were up to 1,000 times higher at 6, 12, and 24 hours post-feeding (PF) compared with those inoculated with 10(3) PFU by needle. Follow-up studies were conducted to determine if enhanced early infection was due to a higher viral dose inoculated by mosquitoes. Needle inoculation with successively higher doses of WNV led to higher early viremia and viral shedding; a dose >or= 10(4) PFU by needle was required to attain the high early viremia observed in mosquito-infected chickens. Mosquitoes inoculated WNV at this level as estimated by feeding on a hanging drop of blood (mean: 10(2.5), range: 10(0.7)-10(4.6) PFU). These results indicate that enhanced early infection in mosquito-infected chickens may be explained by higher viral dose delivered by mosquitoes. On the other hand, chickens infected by multiple mosquitoes (N = 3-11) had viremic titers that were 25-50 times higher at 6 and 12 hours PF than in chickens infected by a single mosquito, suggesting that viral dose is not the only factor involved in enhanced early infection. The likelihood that enhanced early infection in mosquito-infected chickens is due to a higher viral dose inoculated by mosquitoes and/or other factors (saliva, inoculation location, or viral source) is discussed.
虫媒病毒通过蚊子传播可能会影响脊椎动物宿主中的病毒感染进程。开展了多项研究以确定经蚊子叮咬感染西尼罗河病毒（WNV）的鸡与经针头接种感染的鸡，其病毒感染情况是否存在差异。与经针头接种10³ 个空斑形成单位（PFU）的鸡相比，经蚊子感染的鸡在喂食后6、12和24小时的病毒血症水平和病毒排泄量高出多达1000倍。开展了后续研究以确定早期感染增强是否归因于蚊子接种的病毒剂量更高。用剂量不断增加的WNV进行针头接种会导致更高的早期病毒血症和病毒排泄量；经针头接种的剂量≥10⁴ PFU才能达到经蚊子感染的鸡所观察到的高早期病毒血症水平。据通过取一滴悬滴血液喂食估计，蚊子接种WNV的水平为（平均值：10²·⁵，范围：10⁰·⁷ - 10⁴·⁶ PFU）。这些结果表明，经蚊子感染的鸡早期感染增强可能是由于蚊子传递的病毒剂量更高。另一方面，被多只蚊子（N = 3 - 11）感染的鸡在喂食后6和12小时的病毒血症滴度比被单只蚊子感染的鸡高25 - 50倍，这表明病毒剂量并非早期感染增强所涉及的唯一因素。本文讨论了经蚊子感染的鸡早期感染增强是由于蚊子接种的病毒剂量更高和/或其他因素（唾液、接种部位或病毒来源）的可能性。
