Smartt Chelsea T, Richards Stephanie L, Anderson Sheri L, Vitek Christopher J
University of Florida, Institute of Food and Agricultural Sciences, Vero Beach, FL 32962, USA.
Environ Entomol. 2010 Feb;39(1):190-4. doi: 10.1603/EN09172.
Environmental factors that impact the biology of mosquito vectors can have epidemiological implications. Lack of oviposition sites facilitated by environmental factors such as temperature and drought can often force Culex spp. mosquitoes to retain their eggs. Culex pipiens quinquefasciatus Say were fed blood meals containing West Nile virus (WNV; family Flaviviridae, genus Flavivirus) and either allowed to oviposit or forced to retain their eggs through different time points postinfection (9, 13, 20, 27 d) at 28 degrees C. Oviposition status did not significantly affect rates of WNV infection (% with virus-positive bodies), dissemination (% with virus-positive legs), or transmission (% with virus-positive saliva) for any of the tested time points. As expected, WNV titers in bodies and legs were significantly (P < 0.05) higher at late time points compared with early time points. No significant differences were observed in WNV titers in saliva between time points. There were no significant effects of oviposition status on virus titers of bodies, legs, or saliva. However, we found that egg retention may increase vector competence at early and late time points after infection and that a single oviposition event may decrease vector competence, possibly by activating an immune response against the virus. Environmental changes that influence mosquito biology are important determinants of virus transmission, and further studies are needed to assess the effects of drought on virus transmission risk and how these interactions affect our interpretation of field data.
影响蚊媒生物学特性的环境因素可能具有流行病学意义。温度和干旱等环境因素导致产卵场所缺乏，常常会迫使库蚊属蚊子保留其卵。给致倦库蚊喂食含有西尼罗河病毒（WNV；黄病毒科黄病毒属）的血餐，然后在28摄氏度下，让其在感染后的不同时间点（9、13、20、27天）产卵或被迫保留其卵。在任何测试时间点，产卵状态均未显著影响WNV感染率（病毒阳性个体的百分比）、传播率（病毒阳性腿部的百分比）或传播率（病毒阳性唾液的百分比）。正如预期的那样，与早期时间点相比，晚期时间点身体和腿部的WNV滴度显著更高（P < 0.05）。在各时间点之间，唾液中的WNV滴度未观察到显著差异。产卵状态对身体、腿部或唾液的病毒滴度没有显著影响。然而，我们发现保留卵可能会在感染后的早期和晚期时间点增加媒介能力，而单次产卵事件可能会降低媒介能力，这可能是通过激活针对病毒的免疫反应来实现的。影响蚊子生物学特性的环境变化是病毒传播的重要决定因素，需要进一步研究来评估干旱对病毒传播风险的影响以及这些相互作用如何影响我们对现场数据的解释。
