Alpha‐mannosidase‐2 modulates arbovirus infection in a pathogen‐ and Wolbachia‐specific manner in Aedes aegypti mosquitoes

• Published in: Insect molecular biology Vol. 33; no. 4; pp. 362 - 371
• Main Authors: Urakova, Nadya, Joseph, Renuka E., Huntsinger, Allyn, Macias, Vanessa M., Jones, Matthew J., Sigle, Leah T., Li, Ming, Akbari, Omar S., Xi, Zhiyong, Lymperopoulos, Konstantinos, Sayre, Richard T., McGraw, Elizabeth A., Rasgon, Jason L.
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 01-08-2024; Blackwell Publishing Ltd
• Subjects: Aedes aegypti; alpha‐mannosidase‐2; Aquatic insects; Bacteria; Blocking; CRISPR; Culicidae; Dengue fever; dengue virus; Disease transmission; Genetic diversity; Genetics; Infections; Infectious diseases; Mannosidase; Mayaro virus; Mosquitoes; Mutagenesis; Mutation; Pathogens; Phenotypes; Replication; Vector-borne diseases; Viruses; Wolbachia; CRISPR; alpha-mannosidase-2; Wolbachia; Mayaro virus; dengue virus
• ISSN: 0962-1075; 1365-2583; 1365-2583
• DOI: 10.1111/imb.12904

Multiple Wolbachia strains can block pathogen infection, replication and/or transmission in Aedes aegypti mosquitoes under both laboratory and field conditions. However, Wolbachia effects on pathogens can be highly variable across systems and the factors governing this variability are not well understood. It is increasingly clear that the mosquito host is not a passive player in which Wolbachia governs pathogen transmission phenotypes; rather, the genetics of the host can significantly modulate Wolbachia‐mediated pathogen blocking. Specifically, previous work linked variation in Wolbachia pathogen blocking to polymorphisms in the mosquito alpha‐mannosidase‐2 (αMan2) gene. Here we use CRISPR‐Cas9 mutagenesis to functionally test this association. We developed αMan2 knockouts and examined effects on both Wolbachia and virus levels, using dengue virus (DENV; Flaviviridae) and Mayaro virus (MAYV; Togaviridae). Wolbachia titres were significantly elevated in αMan2 knockout (KO) mosquitoes, but there were complex interactions with virus infection and replication. In Wolbachia‐uninfected mosquitoes, the αMan2 KO mutation was associated with decreased DENV titres, but in a Wolbachia‐infected background, the αMan2 KO mutation significantly increased virus titres. In contrast, the αMan2 KO mutation significantly increased MAYV replication in Wolbachia‐uninfected mosquitoes and did not affect Wolbachia‐mediated virus blocking. These results demonstrate that αMan2 modulates arbovirus infection in A. aegypti mosquitoes in a pathogen‐ and Wolbachia‐specific manner, and that Wolbachia‐mediated pathogen blocking is a complex phenotype dependent on the mosquito host genotype and the pathogen. These results have a significant impact for the design and use of Wolbachia‐based strategies to control vector‐borne pathogens.
Mosquito genetic background can modulate Wolbachia pathogen‐blocking phenotypes. The alpha‐mannosidase‐2 gene has previously been identified as a potential candidate.
αMan2 CRISPR KO mutagenesis suppresses dengue virus titres but increases Mayaro virus titres, in Wolbachia‐uninfected mosquitoes.
In a Wolbachia‐infected background, αMan2 KO ablates Wolbachia pathogen blocking but has no effect on Mayaro virus titres.