Malaria vaccine produced from algae

Researchers have developed a new candidate for malaria vaccine by using algae-produced parasite protein.
The protein, paired with an immune-boosting cocktail suitable for use in humans, generated antibodies in mice that nearly eliminated mosquito infection by the malaria parasite.
The method is the newest attempt to develop a vaccine that prevents transmission of the malaria parasite from host to mosquito, researchers said.
"Most malaria vaccine approaches are aimed at preventing humans from becoming infected when bitten by mosquitoes that carry the parasite," said Joseph M Vinetz, senior author of the study, from University of California, San Diego School of Medicine.

"Our approach is to prevent transmission of the malaria parasite from infected humans to mosquitoes," said Vinetz.
The 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, researchers said.
However, properly folded Pfs25 that induces transmission-blocking antibodies has been difficult to produce in the lab.
To overcome this problem, researchers turned to an algae better known for its ability to produce sustainable biofuels.

They introduced the Pfs25 gene into the algae 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.
Vinetz and collaborators at the Infectious Disease Research Institute in Seattle tested several new adjuvants, molecules that help stimulate the immune system's response to Pfs25.
The best Pfs25/adjuvant combination elicited a uniquely robust antibody response in mice with high affinity and avidity - antibodies that specifically and strongly reacted with the malaria parasite's reproductive cells.

Mosquitoes were fed malaria parasites in the presence of control serum or immune serum collected from mice vaccinated with algae-produced Pfs25 in the presence of the new adjuvant.
Eight days later, the researchers examined the mosquitoes' guts for the presence of the malaria parasite.
The results were dramatic: only one of 24 mosquitoes (4.2 per cent) that consumed the Pfs25/adjuvant-treated mouse serum was positive for the malaria parasite. That is compared to the 28 infected mosquitoes out of the 40 in the control group (70 per cent).