Bacterial Infection in
Mosquitoes Renders Them Immune to Malaria Parasites Strategy - Holds Promise
for Malaria Control Efforts
WHAT:
Scientists funded by the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health, have established an inheritable bacterial infection in malaria-transmitting Anopheles mosquitoes that renders them immune to malaria parasites.
Scientists funded by the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health, have established an inheritable bacterial infection in malaria-transmitting Anopheles mosquitoes that renders them immune to malaria parasites.
Specifically, the scientists infected
the mosquitoes with Wolbachia, a bacterium common among insects
that previously has been shown to prevent malaria-inducing Plasmodium parasites
from developing inAnopheles mosquitoes. Before now, researchers had
been unable to create mosquitoes with a stableWolbachia infection
that passed consistently from mother to offspring.
In this study, led by Zhiyong Xi, Ph.D., at
Michigan State University, the researchers focused onAnopheles stephensi mosquitoes,
the primary malaria carrier in the Middle East and South Asia. The scientists
injected Wolbachia into male and female embryos of A.
stephensi and, once they matured, mated the adult females with
uninfected male mosquitoes.
A stable Wolbachia infection
was maintained for 34 generations of mosquitoes, at which time the study ended.
The researchers also introduced Wolbachia infection into
uninfected adult mosquitoes in a series of experiments in which infected female
mosquitoes comprised 5 percent, 10 percent or 20 percent of the mosquito
population.
In all three experiments, 100 percent of the mosquitoes were
infected within eight generations, supporting the potential of Wolbachia-infected
mosquitoes as a malaria control strategy. Similar approaches have been used
successfully to control dengue, another mosquito-borne disease, in certain settings.
In their examination of how Wolbachia affects Plasmodium parasites,
the researchers found that the bacterium kills the parasites both in the
mosquito midgut, where the parasites mature, and in the salivary glands, from
which the parasites are transmitted to humans via mosquito bites.
The
scientists hypothesize that Wolbachia infection causes the
formation of unstable compounds known as reactive oxygen species (ROS), which
inhibit the development of the parasites. Future studies might examine whether Plasmodiumcan
become resistant to ROS and explore ways to integrate Wolbachia-infected
mosquitoes with existing malaria control strategies, the researchers write.
ARTICLE:
Bian G et al. Wolbachia invades Anopheles stephensi populations and induces refractoriness to Plasmodium infection. Science. DOI:
Bian G et al. Wolbachia invades Anopheles stephensi populations and induces refractoriness to Plasmodium infection. Science. DOI:
WHO:
Adriana Costero-Saint Denis, Ph.D., vector biology program officer in NIAID’s Parasitology and International Programs Branch, is available to discuss the findings.
Adriana Costero-Saint Denis, Ph.D., vector biology program officer in NIAID’s Parasitology and International Programs Branch, is available to discuss the findings.
CONTACT:
To schedule interviews, please contact Nalini Padmanabhan, (301) 402-1663, niaidnews@niaid.nih.gov.
To schedule interviews, please contact Nalini Padmanabhan, (301) 402-1663, niaidnews@niaid.nih.gov.
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