Université de La Réunion, UMR PIMIT (Processus Infectieux en Milieu Insulaire Tropical), CNRS 9192, INSERM 1187, IRD 249, La Réunion, France.
Unité Mixte de Recherche Animal Santé Territoires Risques Écosystèmes, F-34398, CIRAD/INRAE/Université de Montpellier, Université de Montpellier, Montpellier, France.
PLoS One. 2024 Sep 19;19(9):e0310635. doi: 10.1371/journal.pone.0310635. eCollection 2024.
Dengue virus (DENV) is the most prevalent mosquito-borne Flavivirus that affects humans worldwide. Aedes albopictus, which is naturally infected with the bacteria Wolbachia, is considered to be a secondary vector of DENV. However, it was responsible for a recent DENV outbreak of unprecedented magnitude in Reunion Island, a French island in the South West Indian Ocean. Moreover, the distribution of the cases during this epidemic showed a spatially heterogeneous pattern across the island, leading to questions about the differential vector competence of mosquito populations from different geographic areas. The aim of this study was to gain a better understanding of the vector competence of the Ae. albopictus populations from Reunion Island for local DENV epidemic strains, while considering their infection by Wolbachia. Experimental infections were conducted using ten populations of Ae. albopictus sampled across Reunion Island and exposed to three DENV strains: one strain of DENV serotype 1 (DENV-1) and two strains of DENV serotype 2 (DENV-2). We analyzed three vector competence parameters including infection rate, dissemination efficiency and transmission efficiency, at different days post-exposition (dpe). We also assessed whether there was a correlation between the density of Wolbachia and viral load/vector competence parameters. Our results show that the Ae. albopictus populations tested were not able to transmit the two DENV-2 strains, while transmission efficiencies up to 40.79% were observed for the DENV-1 strain, probably due to difference in viral titres. Statistical analyses showed that the parameters mosquito population, generation, dpe and area of sampling significantly affect the transmission efficiencies of DENV-1. Although the density of Wolbachia varied according to mosquito population, no significant correlation was found between Wolbachia density and either viral load or vector competence parameters for DENV-1. Our results highlight the importance of using natural mosquito populations for a better understanding of transmission patterns of dengue.
登革热病毒（DENV）是全球流行的最普遍的蚊媒黄病毒。白纹伊蚊（Aedes albopictus）自然感染沃尔巴克氏体（Wolbachia），被认为是 DENV 的次要传播媒介。然而，它是最近在留尼汪岛（法属印度洋西部的一个法国岛屿）爆发的前所未有的 DENV 疫情的罪魁祸首。此外，该疫情期间病例的分布在整个岛屿上呈现出空间异质模式，这引发了关于来自不同地理区域的蚊子种群的差异媒介效能的问题。本研究的目的是更好地了解留尼汪岛的白纹伊蚊种群对当地 DENV 流行株的媒介效能，同时考虑它们感染沃尔巴克氏体的情况。使用从留尼汪岛采集的十个白纹伊蚊种群进行了实验感染，并将其暴露于三种 DENV 株：一种 DENV 血清型 1（DENV-1）株和两种 DENV 血清型 2（DENV-2）株。我们分析了三个媒介效能参数，包括感染率、传播效率和传播效率，在不同的暴露后天数（dpe）。我们还评估了沃尔巴克氏体密度与病毒载量/媒介效能参数之间是否存在相关性。我们的结果表明，测试的白纹伊蚊种群不能传播两种 DENV-2 株，而 DENV-1 株的传播效率高达 40.79%，这可能是由于病毒滴度的差异。统计分析表明，蚊种群、世代、dpe 和采样区域是影响 DENV-1 传播效率的重要因素。尽管沃尔巴克氏体的密度因蚊子种群而异，但未发现沃尔巴克氏体密度与 DENV-1 的病毒载量或媒介效能参数之间存在显著相关性。我们的结果强调了使用自然蚊子种群来更好地理解登革热传播模式的重要性。
