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Published on: September 12, 2020
An Aedes aegypti-associated fungus increases susceptibility to dengue virus by modulating gut trypsin activity
Yesseinia I Angleró-Rodríguez1, Octavio Ac Talyuli1, Benjamin J Blumberg1
1W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, United States.
Abstract:
Transmission of dengue virus (DENV) requires successful completion of the infection cycle in the Aedes aegypti vector, which is initiated in the midgut tissue after ingestion of an infectious blood meal. While certain Ae. aegypti midgut-associated bacteria influence virus infection, little is known about the midgut-associated fungi (mycobiota), and how its members might influence susceptibility to DENV infection. We show that a Talaromyces (Tsp_PR) fungus, isolated from field-caught Ae. aegypti, render the mosquito more permissive to DENV infection. This modulation is attributed to a profound down-regulation of digestive enzyme genes and trypsin activity, upon exposure to Tsp_PR-secreted factors. In conclusion, we show for the first time that a natural mosquito gut-associated fungus can alter Ae. aegypti physiology in a way that facilitates pathogen infection.
Insights
A newly discovered gut fungus, Talaromyces (Tsp_PR), makes Aedes aegypti mosquitoes more susceptible to dengue virus (DENV) infection. This occurs because the fungus disrupts the mosquito's digestive enzymes, aiding pathogen transmission.
Area of Science:
- Vector-borne disease research
- Microbial ecology
- Insect-pathogen interactions
Background:
- Dengue virus (DENV) transmission relies on successful infection of the Aedes aegypti mosquito vector, initiated in the midgut.
- While gut bacteria's role in DENV infection is known, the influence of gut fungi (mycobiota) remains largely unexplored.
Purpose of the Study:
- To investigate the impact of mosquito midgut-associated fungi on Aedes aegypti susceptibility to DENV.
- To identify specific fungal species and their mechanisms of action in modulating DENV infection.
Main Methods:
- Isolation of fungi from field-caught Aedes aegypti mosquitoes.
- Exposure of mosquitoes to fungal isolates and secreted factors.
- Assessment of mosquito permissiveness to DENV infection.
- Analysis of midgut gene expression, focusing on digestive enzymes and trypsin activity.
Main Results:
- A specific fungus, Talaromyces (Tsp_PR), isolated from Aedes aegypti, was found to increase mosquito permissiveness to DENV infection.
- Exposure to Tsp_PR-secreted factors led to significant downregulation of digestive enzyme genes and reduced trypsin activity in the mosquito midgut.
- This physiological alteration by the fungus facilitates DENV infection in the vector.
Conclusions:
- This study demonstrates for the first time that a naturally occurring mosquito gut fungus can enhance DENV infection susceptibility.
- The fungus Talaromyces (Tsp_PR) alters Aedes aegypti midgut physiology by downregulating digestive enzymes, thereby facilitating pathogen infection.
- These findings highlight the potential role of the mosquito mycobiota in vector competence and DENV transmission dynamics.
