New mRNA vaccines highly effective in reducing malaria infection: Study

Scientists have developed two mRNA vaccine candidates that were highly effective in reducing both malaria infection and transmission in animal studies.

The team from George Washington University, US, also found that the two vaccines induced a powerful immune response regardless of whether they were given individually or in combination.

The mRNA vaccines work by introducing a piece of messenger RNA -- RNA that is necessary for protein production -- which corresponds to a viral protein.

"Malaria elimination will not happen overnight but such vaccines could potentially banish malaria from many parts of the world,” said Nirbhay Kumar, a professor at the George Washington University Milken Institute School of Public Health.

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"The mRNA vaccine technology can really be a game changer. We saw how successful this technology was in terms of fighting Covid and for this study we adapted it and used it to develop tools to combat malaria," Kumar said in a statement.

The study, published on Thursday in the journal npj Vaccines, focused on the parasite Plasmodium falciparum, one of four parasite species that cause malaria and the deadliest to humans.

Transmitted through the bite of the Anopheles mosquito, P. falciparum together with P. vivax are responsible for more than 90 per cent of all malaria cases globally, and 95 per cent of all malaria deaths, the researchers said.

Most cases and deaths occur in sub-Saharan Africa but half the world's population is at risk of contracting this deadly disease, they said.

The researchers developed two mRNA vaccines to disrupt different parts of the parasite's life cycle. They immunised one group of mice with a mRNA vaccine targeting a protein that helps the parasites move through the body and invade the liver.

The team immunised another group of mice with a vaccine targeting a protein that helps parasites reproduce in a mosquitoe's midgut.

The immunised mice were then challenged with the parasite causing infection and vaccine induced antibodies were tested to interrupt malaria transmission.

The study found both vaccines induced a potent immune response in the mice and were highly effective in reducing infection in the host and in the mosquito vector.

The presence of protective antibodies during transmission of parasites to healthy mosquitoes dramatically reduced the parasite load in the mosquitoes, an important step in disrupting malaria transmission, according to the researchers.

"These vaccines were highly effective at preventing infection and they wiped out transmission potential almost entirely,” Kumar said.

The team also immunised mice with both vaccines together and found that co-immunisation effectively reduced infection and transmission without compromising the immune response.

The mRNA vaccines were also found to be far superior in inducing an immune response compared to the DNA-based vaccines, they found.

The researchers hope to usher the vaccines through additional research, including studies in nonhuman primate models, with the goal of producing vaccines that can be used safely in humans.

"To have a vaccine cocktail that can effectively disrupt multiple parts of the malaria parasite's life cycle is one of the holy grails of malaria vaccine development," Kumar added.