Bacterial warriors fight mosquito-borne diseases

Alejandra Manjarrez,  Drug Discovery News,  2024.

Every time a mosquito bites a person, multiple feasts take place. As in most animals, a meal provides nutrients to the mosquito as well as to the troop of bacteria that inhabits its gut. Occasionally, the mosquito may also ingest a parasite: a Plasmodium protozoan responsible for malaria in humans, or an arbovirus, which can cause dengue, chikungunya, Zika, or yellow fever. The pathogen is just along for the ride, but those first hours after being ingested are crucial for its survival. The parasite develops in the insect’s midgut lumen, and any interference during this period may hamper its future survival and transmission.

When the mosquito ingests blood, the number of bacteria in its midgut increases dramatically. “That’s easy to understand because they use the nutrients of the blood to multiply,” noted Marcelo Jacobs-Lorena, a malaria researcher at the Johns Hopkins Bloomberg School of Public Health. “You have a few parasites surrounded by a huge number of bacteria.” These bacteria become promising targets for intervening in the development of parasites during their most vulnerable stages, either by competing for resources or directly attacking the threat. In the ongoing battle against mosquito-borne diseases that kill more than a million people each year, scientists like Jacobs-Lorena increasingly turn to mosquito microbiota as allies in disease prevention (1). Delving into the guts and other bacteria-inhabited parts of mosquitoes is beginning to bear fruit. The performance of these bacteria in laboratory and semi-field experiments is promising. Releasing mosquitoes armed with a virus-fighting bacterium in cities affected by dengue significantly decreased its incidence in those locations. While these interventions don’t offer a silver bullet against mosquito-borne diseases, they appear to be a game-changer in the fight against those deadly parasites.

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