Effect of naturally-occurring Wolbachia in Anopheles gambiae s.l. mosquitoes from Mali on Plasmodium falciparum malaria transmission

Authors: GOMES, FABIO - National Institute Of Health (INSA); HIXSON, BRETTA - National Institute Of Health (INSA); TYNER, MILES - National Institute Of Health (INSA); Ramirez, Jose; CANEPA, GASPAR - National Institute Of Health (INSA); ALVES E SILVA, THIAGO - National Institute Of Health (INSA); MOLINA-CRUZ, ALVARO - National Institute Of Health (INSA); KEITA, MOUSSA - University Of Bamako; KANE, FOUSEYNI - University Of Bamako; TRAORE, BOISSE - University Of Bamako; SOGOBA, NAFOMON - University Of Bamako; BARILLAS-MURY, CAROLINA - National Institute Of Health (INSA)

Submitted to: Proceedings of the National Academy of Sciences (PNAS)
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/7/2017
Publication Date: 11/21/2017
Citation: Gomes, F.M., Hixson, B.L., Tyner, M.D., Ramirez, J.L., Canepa, G.E., Alves E Silva, T.L., Molina-Cruz, A., Keita, M., Kane, F., Traore, B., Sogoba, N., Barillas-Mury, C. 2017. Effect of naturally-occurring Wolbachia in Anopheles gambiae s.l. mosquitoes from Mali on Plasmodium falciparum malaria transmission. Proceedings of the National Academy of Sciences. 114:12566-12571. doi: 10.1073/pnas.1716181114.
DOI: https://doi.org/10.1073/pnas.1716181114

Interpretive Summary: A novel naturally-occurring Wolbachia strain was identified in mosquitoes of the A. gambiae complex collected in the Malian villages of Dangassa and Kenieroba (wAnga-Mali). wAnga-Mali is different from two Wolbachia strains previously reported in A. gambiae from Burkina Faso (wAnga_VK5_STP and wAnga_VK5_3.1a). Quantitative assays of Plasmodium infection and Wolbachia conducted in field-collected mosquitoes indicated that the level of parasite infection was lower in Wolbachia-infected females. Further assays in the lab with a strain of lab-reared mosquito corroborated this results, with Wolbachia-carrying mosquitoes presenting a lower level of parasite in the salivary glands compared to those that were cured of Wolbachia.

Technical Abstract: A novel naturally-occurring Wolbachia strain was identified in mosquitoes of the A. gambiae complex collected in the Malian villages of Dangassa and Kenieroba (wAnga-Mali). Phylogenetic analysis of the nucleotide sequence of two 16S rRNA regions showed that wAnga-Mali clusters with Wolbachia strains from Supergroup A, and has the highest homology to a Wolbachia strain isolated from cat fleas (Ctenocephalides). wAnga-Mali is different from two Wolbachia strains previously reported in A. gambiae from Burkina Faso (wAnga_VK5_STP and wAnga_VK5_3.1a). Quantitative analysis of Wolbachia and Plasmodium sporozoite infection in field-collected mosquitoes indicates that the prevalence and intensity of P. falciparum sporozoite infection is significantly lower in Wolbachia-infected females. The presence of Wolbachia in females from a laboratory A. coluzzii (A. gambiae, M-form) colony experimentally infected with P. falciparum (NF54 strain) gametocyte cultures slightly enhanced oocyst infection. However, Wolbachia-infection significantly reduced the prevalence and intensity of sporozoite infection, as observed in the field. This indicates that Wolbachia infection does not limit early stages of Plasmodium infection in the mosquito, but has a strong deleterious effect on sporozoites and reduces malaria transmission.