Certain bacteria render mosquitoes resistant to deadly malaria parasite
For Immediate Release: Monday, May 16, 2011
Scientists have identified a class of naturally occurring bacteria that can strongly inhibit malaria-causing parasites in Anopheles mosquitoes, a finding that could have implications for efforts to control malaria. The study, led by George Dimopoulos, Ph.D., of the Bloomberg School of Public Health and the Malaria Research Institute, both of Johns Hopkins University, Baltimore, appears in the May 13 edition of Science. The research was partly funded by the National Institute of Allergy and Infectious Diseases (NIAID), a component of the National Institutes of Health.
According to the World Health Organization, an estimated 225 million malaria cases occur worldwide annually, resulting in about 781,000 deaths. Although the disease is present in 106 countries, most cases occur in sub-Saharan Africa. Insect repellent and bed nets can help prevent transmission of the malaria parasite from mosquitoes to humans, but to control malaria one step earlier, some studies are looking to eliminate infection within the mosquito itself.
“This discovery may explain why some mosquitoes are better than others at transmitting malaria to humans, even when they are of the same species,” explained NIAID Director Anthony S. Fauci, M.D.
“Our study used a laboratory method of P. falciparum infection, which causes stronger infections than those that take place in a natural environment,” explained Dr. Dimopoulos. “We believe that in a natural situation, where infection levels are much lower, this bacterium would eliminate the parasite. Further, there is no evidence that Enterobacter is toxic to either mosquitoes or humans.”
By observing the interaction between the bacteria and the parasite, the scientists determined that Enterobacter inhibits parasite growth by producing short-lived molecules known as reactive oxygen species (ROS). Although ROS travel through body fluids in the mosquito, they do not need to be in a mosquito to inhibit parasites.
Future research plans include sequencing the Enterobacter genome to better comprehend how it produces malaria-inhibiting ROS and studying other bacteria that reside in the mosquito gut to learn whether they have similar effects.
“If we can find a correlation between mosquitoes malaria infection status and the presence or absence of a particular bacterium, it may suggest that the bacterium inhibits malaria parasites,” stated Dr. Dimopoulos. Identifying a variety of malaria-inhibiting bacteria would be especially useful since not all mosquitoes have Enterobacter in their guts.
The researchers hope to apply their findings to the field, where they would first alter Enterobacter for use in mosquitoes. The next step would be to strategically place the bacteria in the mosquitoes natural environment, such as in their sugar food sources or breeding sites. Although these strategies have not yet been tested in malaria prevention, sugar baits have been used successfully to expose mosquitoes to toxins.
“This is a novel way of looking at how the mosquito and malaria parasite interact,” stated Adriana Costero-Saint Denis, Ph.D., program officer in NIAIDs Vector Biology Program. “It adds another layer to the study of malaria.”
For more information about NIAIDs malaria research, see the NIAID malaria Web portal.
About the National Institutes of Health (NIH): NIH, the nation’s medical research agency, includes 27 Institutes and Centers and is a component of the U.S. Department of Health and Human Services. NIH is the primary federal bureau conducting and supporting basic, clinical, and translational medical research, and is investigating the causes, treatments, and cures for both common and rare diseases. For more information about NIH and its programs, visit www.nih.gov.
Reference: C Cirimotich et al. Natural microbe-mediated refractoriness to Plasmodium infection in Anopheles gambiae. Science DOI: 10.1126/science.1201618 (2011).
More source:
Certain bacteria render mosquitoes resistant to deadly malaria - NIHScientists engineer mosquito immune system to fight malaria
Learn more about george dimopoulos | e! Science News
Mosquito immune system engineered to block malaria
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