Multiple mosquito AMPs are needed to potentiate their antifungal effect against entomopathogenic fungi

Authors: Ramirez, Jose; Hampton, Kylie; ROSALES, ALAYNA - Bradley University; Muturi, Ephantus

Submitted to: Frontiers in Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/12/2022
Publication Date: 1/6/2023
Citation: Ramirez, J.L., Hampton, K.J., Rosales, A.M., Muturi, E.J. 2023. Multiple mosquito AMPs are needed to potentiate their antifungal effect against entomopathogenic fungi. Frontiers in Microbiology. 13. Article 1062383. https://doi.org/10.3389/fmicb.2022.1062383.
DOI: https://doi.org/10.3389/fmicb.2022.1062383

Interpretive Summary: Mosquito born diseases continue to be a significant public health problem around the world. Biological control of mosquitoes is considered a sustainable and eco-friendly alternative to the use of synthetic chemical pesticides. The efficacy of biological control agents depends upon the virulence of the microbial agent as well as on mosquito-derived factors that protects it from microbial infection. This study describes several proteins the mosquito uses to resist fungal infection. Furthermore, it appears that these proteins are acting in unison, rather than individually, to control fungal proliferation inside the mosquito. This study contributes to a better understanding of the mechanisms that confer resistance to insect-killiing fungi in an important mosquito vector. This new information will also allow us to improve fungal-based mosquito control strategies by integrating entomopathogenic fungal strains with distinct modes of action.

Technical Abstract: Mosquito resistance to microbial infections, including fungal entomopathogens that are selected for mosquito control, depend on a range of antimicrobial effectors, among them antimicrobial peptides (AMPs). These short peptides, along the antimicrobial effector lysozyme, act by disrupting the microbial cell membrane or by interfering with microbial physiological processes. While the induction of AMPs and lysozyme during fungal entomopathogenic infections have been reported, their contribution to the mosquito antifungal response has not been evaluated. In this study, we assessed the induction of Ae. aegypti AMPs and lysozyme genes at two points of infection and against two different entomopathogenic fungi, Beauveria bassiana and Isaria javanica. Our results indicate that fungal infection elicits the expression of cecropin, defensin, diptericin, holotricin and lysozyme, but do not affect those of attacin or gambicin. We further evaluated the role of these antimicrobial effectors via RNAi-based depletion of select AMPs during challenges with two entomopathogenic fungi. Our results reveal that AMPs and lysozyme are critical to the antifungal response, acting in concert, rather than individually, to potentiate their antimicrobial effect against entomopathogenic fungi. This study further contributes to a better understanding of the mechanisms that confer resistance to entomopathogenic fungi in an important mosquito vector.