If there is one thing that the malaria parasite will, it is to penetrate into the bowels of a mosquito. Once there, it releases hundreds of giant cells which enter the human body through a blood-bite. Now scientists have found a way to make the mosquitoes less welcoming to this pathogen, and one that causes dengue. Stacking the gut of the insect killer with microbes that destroy the invaders before they have a chance to cause disease
Like humans and most other animals, mosquitoes are stuffed with microbes that live on and inside them-their microbiome. By studying the microbes that make their house mosquitoes, the researchers met one called Chromobacterium sp. (Csp_P). They already knew that the relatives of Csp_P were able to produce potent antibiotics, and they wondered if Csp_P could share the same talent.
The team Csp_P grown in a solution of sugar in the blood and fed two concoctions mosquitoes whose natural microbiomes had already been eliminated with doses of antibiotics. As scientists hoped, Csp_P quickly took on the mosquito gut after being ingested through the sugar solution and even faster when it was fed to them in blood. In another experiment, made with mosquitoes that are not pretreated with antibiotics, fed Csp_P mosquitoes have received blood containing dengue virus and Plasmodium falciparum , a single-celled parasite that causes type the deadliest malaria. Although many of the mosquitoes died days after being infected with Chromobacterium , pathogenic malaria and dengue were much less able to infect mosquitoes that survive, reports the team today in the PLoS Pathogens . That's good news :. If the mosquito is infected with pathogens, it is less likely to be able to transmit pathogens to humans
The team of Johns Hopkins University in Baltimore, Maryland, also exposed the malaria parasite and dengue virus to Csp_P laboratory cultures to test anti- Plasmodium and dengue activity. Again, they found that bacteria inhibit the growth of pathogens.
The researchers say there could be two mechanisms by which Csp_P fights infections Plasmodium and dengue. First, because Csp_P is toxic to mosquitoes, it activates the immune system of the insect. This has the collateral benefit to stave off infection Plasmodium and the dengue virus, which otherwise would have thrived in the mosquito gut. But that's not all, 'said George Dimopoulos, parasitology at Johns Hopkins, who led the research team. Because the bacteria also sniffs Plasmodium and the dengue virus in the laboratory, it means Csp_P is the production of toxic compounds which kill pathogens.
Dimopoulos and his colleagues believe Csp_P could be used to "inoculate" mosquitoes against pathogens of malaria and dengue fever, perhaps through the use of baited traps sugar which are already used to spreading insecticide in pest populations. This would have the dual effect of killing most mosquitoes while severely limiting the ability of survivors to spread the disease. This double whammy is "a unique property" for all malaria control agent, said David Fidock, a microbiologist at Columbia University, who was not involved in the study. "No current agent fight against malaria does both."
Csp_P could also play a more direct role in the fight against malaria and dengue fever in humans. Because the compounds it secretes kill pathogens in the laboratory, these toxins could be turned into drugs to treat malaria and dengue fever in people.
Tanjore Balganesh, medicinal chemist who runs the Open Source Drug Discovery program in Bangalore India for diseases such as malaria and tuberculosis neglected, is skeptical, however. Because Csp_P is so toxic to Plasmodium , the dengue virus, and even the mosquito that carries them, there is a good chance it could be harmful to human cells, too, he said . This is not a death blow to this line of investigation, however. "It's still early [for this research]," he said, "but no drug discovery program without problems."
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