Malaria, a disease that has plagued humanity for centuries, continues to claim millions of lives each year. But scientists may have found a new way to combat this deadly disease. In clinical trials, the London School of Hygiene and Tropical Medicine has demonstrated that mosquito bites can deliver the malaria vaccine safely. This novel vaccination strategy involves using genetically modified mosquitoes.
The team investigated Plasmodium falciparum – the parasite responsible for the most severe form of malaria. They explored the possibility of genetically modifying P. falciparum to function as a vaccine rather than a disease-causing agent.
These mosquitoes carry a weakened form of the malaria parasite, designed to trigger a powerful immune response in humans.
Stops the multiplication of parasites in the body
These parasites sneak into the liver and then invade red blood cells, causing havoc in the human body.
The currently licensed vaccines offer limited protection. These subunit vaccines target specific proteins in the malaria parasite, inducing an immune response. However, the parasite's ability to mutate and evade the immune system often limits the long-term efficacy of these vaccines.
Live-attenuated Plasmodium falciparum parasites offer a promising alternative vaccination strategy.
When administered as a vaccine, these weakened parasites stimulate a robust immune response against multiple stages of the parasite's life cycle.
“Currently licensed and approved malaria subunit vaccines provide modest, short-lived protection against malaria. Immunization with live-attenuated Plasmodium falciparum malaria parasites is an alternative vaccination strategy that has potential to improve protection,” the study noted.
Provides 89 percent protection against malaria
In the trial, the volunteers were bitten by mosquitoes carrying a special, modified version of the malaria parasite. The idea is that by exposing people to a controlled dose of the parasite, their immune systems can learn to fight off future infections.
As per Nature, the engineered parasites were programmed to undergo developmental arrest shortly after entering the body.
The vaccine used a genetically modified malaria parasite (GA2) designed to stop developing early in the human liver. It ceases development six days after infecting a person, right when it's about to multiply in the liver.
Participants were divided into three groups: one group received the GA2 vaccine, another received an earlier version (GA1), and the control group received bites from uninfected mosquitoes. The primary goal was to assess the vaccine's ability to prevent malaria infection and its safety profile.
After three weeks, both groups were exposed to malaria-carrying mosquitoes to assess their level of protection.
Before being exposed to malaria-carrying mosquitoes, both groups showed increased antibody levels. However, the GA1 group had a lower protection rate (13 percent) compared to the group bitten by GA2 parasite at 89 percent. The only reported side effects were minor itching from the mosquito bites.
“Protective efficacy against subsequent controlled human malaria infection was observed in 8 of 9 participants (89 percent) in the GA2 group, in 1 of 8 participants (13 percent) in the GA1 group, and in 0 of 3 participants in the placebo group,” the study noted.
Up next, the researchers plan to conduct a larger trial.
