Novel Wolbachia strains in Anopheles malaria vectors from Sub-Saharan Africa

Abstract

Anopheles (An.) mosquitoes contain bacteria that can influence Plasmodium parasites. Wolbachia, a common insect endosymbiont, has historically been considered absent from Anopheles but has recently been found in An. gambiae populations. Here, we assessed a range of Anopheles species from five malaria-endemic countries for Wolbachia and Plasmodium infection. Strikingly, we found Wolbachia infections in An. coluzzii, An. gambiae s.s, An. arabiensis, An. moucheti and An. species ‘A’ increasing the number of Anopheles species known to be naturally infected by this endosymbiont. Molecular analysis suggests the presence of phylogenetically diverse novel strains, while qPCR and 16S rRNA sequencing indicates that Wolbachia is the dominant member of the microbiota in An. moucheti and An. species ‘A’. We found no evidence of Wolbachia/Asaia co-infections, and presence of these endosymbionts did not have significant effects on malaria prevalence. We discuss the importance of novel Wolbachia strains in Anopheles and potential implications for disease control.

NaturalWolbachiainfections are common in the major malaria vectors in Central Africa

“…In arthropods, Wolbachia is broadly spread, including among Culex and Aedes mosquitoes. Conversely, it was believed that in the genus Anopheles, Wolbachia infections were mainly limited to species within the gambiae complex 23,25 , and few other species 22 . Several hypotheses can be put forward to explain this.…”

“…Unfortunately, only one stable transfected Wolbachia colony has been described in Anopheles stephensi 18 . Therefore, data on the use Wolbachia for Anopheles control remain scarce and mainly concern experimental studies in laboratory conditions 18,19 , due to technical (i.e., egg microinjection) and biological (i.e., competitive exclusion with the bacterium Asaia) difficulties to carry out transinfections in Anopheles , despite multiple assays 20–22 For long time, it was believed that Wolbachia was absent in natural populations of Anopheles 20 . However, in the last few years, three studies reported that An.…”

“…Noteworthy, they showed a negative correlation between Wolbachia infection and Plasmodium development 24,25 . Moreover, a very recent report suggests that other Anopheles species also are infected with Wolbachia 22 . These findings support the development of novel vector control strategies based on Wolbachia-Anopheles interactions.…”

Diverse novel residentWolbachiastrains in Culicine mosquitoes from Madagascar

“…albopictus populations in Madagascar (including resident Wolbachia strains) concluded that the environment was a factor in the overall microbiota composition and diversity 68 . It has also recently been shown that there is no evidence for Wolbachia-Asaia co-infections in a wide range of Anopheles species and the environment likely influences Asaia prevalence and density in wild mosquito populations 69 .…”

Biological Control of Mosquito-Borne Diseases: The Potential ofWolbachia-Based Interventions in an IVM Framework

“…darlingi ), which has led to the previous believe that Wolbachia were unable to infect Anopheles species until their very recent discovery in natural populations of Anopheles gambiae and Anopheles coluzzii in Burkina Faso [21, 65] and in Mali (Gomes et al 2017). More recently Ayala et al [66] and Jeffries et al [67] have revealed that native Wolbachia infections was wider than expected among natural anopheline populations with at least 16 species naturally infected (Table 4). Furthermore, Ayala et al [66] revealed a large diversity of Wolbachia strains in wild anopheline populations, which offers an unexpected opportunity to discover suitable phenotypes to suppress Plasmodium transmission and/or to manipulate Anopheles reproduction and reduces the malaria burden in Africa [66].…”