Laboratório de Biologia Molecular de Insetos, Instituto Oswaldo Cruz, Fiocruz, Rio de Janeiro, RJ, Brazil.
Laboratório de Fisiologia e Controle de Artrópodes Vetores, Instituto Oswaldo Cruz, Fiocruz, Rio de Janeiro, RJ, Brazil.
Parasit Vectors. 2019 May 6;12(1):211. doi: 10.1186/s13071-019-3474-z.
Aedes aegypti is a major disease vector in urban habitats, involved in the transmission of dengue, chikungunya and Zika. Despite innumerous attempts to contain disease outbreaks, there are neither efficient vaccines nor definite vector control methods nowadays. In recent years, an innovative strategy to control arboviruses, which exploits the endosymbiotic bacterium Wolbachia pipientis, emerged with great expectations. The success of the method depends on many aspects, including Wolbachia's cytoplasmic incompatibility and pathogen interference phenotypes, as well as its effect on host fitness. In this work, we investigated the influence the Wolbachia strain wMel exerts on embryo development and egg viability and speculate on its field release use.
Wild-type (Br or Rockefeller) and Wolbachia-harboring specimens (wMelBr) were blood-fed and submitted to synchronous egg laying for embryo development assays. Samples were analyzed for morphological markers, developmental endpoint and egg resistance to desiccation (ERD). Quiescent egg viability over time was also assessed.
wMelBr samples completed embryogenesis 2-3 hours later than wild-type. This delay was also observed through the onset of both morphological and physiological markers, respectively by the moments of germband extension and ERD acquisition. Following the end of embryonic development, wMelBr eggs were slightly less resistant to desiccation and showed reduced viability levels, which rapidly decayed after 40 days into quiescence, from approximately 75% to virtually 0% in less than a month.
Our data revealed that the wMel strain of Wolbachia slightly delays embryogenesis and also affects egg quality, both through reduced viability and desiccation resistance. These findings suggest that, although embryonic fitness is somehow compromised by wMel infection, an efficient host reproductive manipulation through cytoplasmic incompatibility seems sufficient to overcome these effects in nature and promote bacterial invasion, as shown by successful ongoing field implementation.
埃及伊蚊是城市栖息地中的主要病媒，参与登革热、基孔肯雅热和寨卡病毒的传播。尽管无数次试图控制疾病爆发，但目前既没有有效的疫苗，也没有明确的病媒控制方法。近年来，一种利用共生细菌沃尔巴克氏体控制虫媒病毒的创新策略应运而生，人们对此寄予厚望。该方法的成功取决于许多因素，包括沃尔巴克氏体的细胞质不相容性和病原体干扰表型，以及其对宿主适应性的影响。在这项工作中，我们研究了沃尔巴克氏菌菌株 wMel 对胚胎发育和卵活力的影响，并推测了其野外释放使用的可能性。
对野生型（Br 或 Rockefeller）和携带沃尔巴克氏菌的标本（wMelBr）进行血餐喂养，并进行同步产卵以进行胚胎发育试验。对样本进行形态标记物、发育终点和卵对干燥的抗性（ERD）分析。还评估了随时间推移的静止卵活力。
wMelBr 样本比野生型晚 2-3 小时完成胚胎发生。这种延迟也通过形态和生理标记物的开始来观察到，分别是通过 germband 延伸和 ERD 获得的时刻。胚胎发育结束后，wMelBr 卵对干燥的抵抗力略有降低，活力水平降低，在静止状态下 40 天后迅速下降，在不到一个月的时间内从大约 75%降至几乎为 0%。
我们的数据表明，沃尔巴克氏体的 wMel 菌株略微延迟了胚胎发生，还通过降低活力和干燥抗性来影响卵质量。这些发现表明，尽管 wMel 感染会在某种程度上影响胚胎适应性，但通过细胞质不相容性有效地进行宿主生殖操纵足以克服这些影响在自然界中，并促进细菌入侵，正如正在进行的野外实施所显示的那样。
