NEW DELHI: A small clinical trial of a late-attenuated liver-stage malaria parasite vaccine has shown it to be safe and effective against the mosquito-borne disease that has claimed 608,000 lives globally.
The trial, led by researchers from Leiden University Medical Center and Radboud University Medical Center in the Netherlands, found that immunization with a genetically modified Plasmodium falciparum parasite, known as GA2, induced a favorable immune response, while infection Also protects from
For the trial, the team randomly assigned 25 healthy adult volunteers with no prior exposure to malaria to receive immunizations with a genetically modified P. falciparum parasite (GA2) — which lives in the liver. Designed to continue growing longer.
While 10 participants were assigned to the GA2 group, another 10 were assigned to the GA1 group, and five to the placebo group. Each group consisted of both male and female volunteers.
Three immunization sessions at 28-day intervals involved exposure to 50 mosquitoes infected with the respective parasites or uninfected in the case of the placebo group.
Three weeks after the final immunization, all participants were exposed to controlled human malaria infection to assess protective efficacy.
The results, published in the New England Journal of Medicine, showed that protective efficacy was seen in 89 percent of people in the GA2 group. Only 13 percent in the GA1 group had a protective effect, while those in the placebo group had none.
Further, the team also found that no breakthrough infections occurred after exposure to GA2, indicating a strong protective profile.
GA2 participants also demonstrated a stronger proinflammatory response. Both GA2 and GA1 also induced similar antibody titers against P. falciparum circumsporozoite proteins.
This suggests that the improved protection with GA2 is associated with a cellular immune response rather than just antibody levels, the researchers said.