GSK scientists have discovered a naturally occurring strain of bacterium known as Deftia tsuruhatensis Tress Cantos 1 (TC1) that has been shown to stop the transmission of malaria in humans from mosquitoes.
After a colony of mosquitoes in one experiment did not develop the malaria parasite, researchers found that TC1 could be a new tool for fighting the disease, which kills 600,000 people every year.
The scientists observed that mosquitoes from an An. Stephensi colony in their insectary were unable to sustain P. falciparum infection – a prevalent and fatal type of malaria in Africa as well as other parts of the world. TC1 was found to be responsible for the loss of infectivity.
Dr Janneth Rodrigues, who led the programme, said they observed that mosquito infection rates started “dwindling” and that “by the end of the year, the mosquitoes just would not be infected with the malaria parasite”.
After freezing samples from their 2014 experiment, the team went back to them after two years and found that the bacteria can reduce a mosquito’s parasite load by up to 73%.
Researchers from GSK, John Hopkins and Fundación MEDINA, found that TC1 secreted small quantities of harmane, a molecule that inhibits the early stages of the parasite’s (P. falciparum) development in the mosquito midgut.
Mosquitoes exposed to TC1 or very low concentrations of harmane showed a significant reduction in the Plasmodium parasite, which is transmitted through a mosquito bite to humans.
The bacterium was found to stably populate the mosquito gut, and P. falciparum inhibition lasted over 16 days – potentially for the entirety of the mosquito’s lifespan.
Chief global health officer at GSK, Thomas Breuer, described the bacterium as “an additional tool” and “an entirely novel approach for malaria control”.
He added: “[TC1] has the potential to further reduce the huge burden of malaria in endemic countries and is more evidence that, through deploying a range of prevention approaches, we may be able to finally eradicate this terrible disease.”