Terradas Gerard, Manzano-Alvarez Jaime, Vanalli Chiara, Werling Kristine, Cattadori Isabella M, Rasgon Jason L
Department of Entomology, The Pennsylvania State University, University Park, PA, USA.
Center for Infectious Disease Dynamics, The Pennsylvania State University, University Park, PA, USA.
Parasit Vectors. 2024 Feb 19;17(1):73. doi: 10.1186/s13071-023-06109-0.
Increasing global temperatures and unpredictable climatic extremes have contributed to the spread of vector-borne diseases. The mosquito Aedes aegypti is the main vector of multiple arboviruses that negatively impact human health, mostly in low socioeconomic areas of the world. Co-circulation and co-infection of these viruses in humans have been increasingly reported; however, how vectors contribute to this alarming trend remains unclear.
Here, we examine single and co-infection of Mayaro virus (D strain, Alphavirus) and dengue virus (serotype 2, Flavivirus) in Ae. aegypti adults and cell lines at two constant temperatures, moderate (27 °C) and hot (32 °C), to quantify vector competence and the effect of temperature on infection, dissemination and transmission, including on the degree of interaction between the two viruses.
Both viruses were primarily affected by temperature but there was a partial interaction with co-infection. Dengue virus quickly replicates in adult mosquitoes with a tendency for higher titers in co-infected mosquitoes at both temperatures, and mosquito mortality was more severe at higher temperatures in all conditions. For dengue, and to a lesser extent Mayaro, vector competence and vectorial capacity were higher at hotter temperature in co- vs. single infections and was more evident at earlier time points (7 vs. 14 days post infection) for Mayaro. The temperature-dependent phenotype was confirmed in vitro by faster cellular infection and initial replication at higher temperatures for dengue but not for Mayaro virus.
Our study suggests that contrasting kinetics of the two viruses could be related to their intrinsic thermal requirements, where alphaviruses thrive better at lower temperatures compared to flaviviruses. However, more studies are necessary to clarify the role of co-infection at different temperature regimes, including under more natural temperature settings.
全球气温上升和不可预测的极端气候促使了媒介传播疾病的传播。埃及伊蚊是多种虫媒病毒的主要传播媒介，这些病毒对人类健康产生负面影响，主要发生在世界社会经济水平较低的地区。越来越多的报道称这些病毒在人类中共同传播和共同感染；然而，媒介如何促成这一惊人趋势仍不清楚。
在此，我们在两个恒定温度（适中温度27°C和高温32°C）下，检测了埃及伊蚊成虫和细胞系中马亚罗病毒（D株，甲病毒属）和登革病毒（血清型2，黄病毒属）的单一感染和共同感染情况，以量化媒介能力以及温度对感染、传播和传播的影响，包括对两种病毒之间相互作用程度的影响。
两种病毒主要受温度影响，但共同感染存在部分相互作用。登革病毒在成年蚊子中迅速复制，在两种温度下共同感染的蚊子中滴度往往更高，并且在所有条件下高温时蚊子死亡率更高。对于登革病毒，在一定程度上对于马亚罗病毒，共同感染与单一感染相比，在较高温度下媒介能力和媒介能量更高，并且对于马亚罗病毒在早期时间点（感染后7天与14天）更明显。通过登革病毒在较高温度下更快的细胞感染和初始复制（但马亚罗病毒未出现此情况）在体外证实了温度依赖性表型。
我们的研究表明，两种病毒截然不同的动力学可能与其内在的热需求有关，与黄病毒相比，甲病毒在较低温度下生长得更好。然而，需要更多研究来阐明不同温度条件下共同感染的作用，包括在更自然的温度环境下。
