A team of scientists has produced malaria vaccine candidate from algae that prevents transmission of the malaria parasite from host to mosquito.
Researchers at University of California, San Diego School of Medicine used algae as a mini-factory to produce a malaria parasite protein, which paired with an immune-boosting cocktail suitable for use in humans, generated antibodies in mice that nearly eliminated mosquito infection by the malaria parasite.
Senior author Joseph M. Vinetz said that most malaria vaccine approaches are aimed at preventing humans from becoming infected when bitten by mosquitos that carry the parasite, but their approach is to prevent transmission of the malaria parasite from infected humans to mosquitoes.
Vinetz added that this approach is similar to that of the current measles vaccine, which is such a hot topic of discussion these days, because the goal is to generate herd immunity in a population. They think that this approach is key to global malaria elimination, too.
To do this, Vinetz and team wanted to produce a large quantity of properly folded Pfs25, a protein found on the surface of the malaria parasite's reproductive cells, which are only present within the mosquito's gut after it feeds on a malaria-infected blood meal. Since antibodies against Pfs25 can halt the parasite's lifecycle in the mosquito, they might also block transmission of the parasite to the next host.
However, properly folded Pfs25 that induces transmission-blocking antibodies has been difficult to produce in the lab and so researchers introduced the Pfs25 gene into the algae, better known for its ability to produce sustainable bio-fuels, by shooting the DNA into the plant cell's nucleus. Then, after they let the algae do the work of replicating, building and folding the protein, the team was able to purify enough functional Pfs25 for laboratory testing.
Besides its effectiveness as a protein producer, algae are an advantageous tool for developing vaccines because it's cheap, easy and environmentally friendly. The only requirement is simple chemical nutrients to feed the algae, which can be grown in plastic bags and easily scaled up to produce large quantities of desired proteins.
The study is published by Infection and Immunity.