Researchers led by a team from George Washington University report they have developed two mRNA vaccine candidates that are effective in reducing both malaria infection and transmission. The team also observed the two experimental vaccines induced a powerful immune response regardless of whether they were given individually or in combination.
Their findings are published in npj Vaccines in an article titled, “mRNA-LNP expressing PfCSP and Pfs25, two leading vaccine candidates targeting infection and transmission of Plasmodium falciparum.”
“Malaria elimination will not happen overnight but such vaccines could potentially banish malaria from many parts of the world,” Nirbhay Kumar, a professor of global health at the George Washington University Milken Institute School of Public Health, said. “The mRNA vaccine technology can really be a game changer. We saw how successful this technology was in terms of fighting COVID-19 and for this study we adapted it and used it to develop tools to combat malaria.”
Kumar and the research team 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% of all malaria cases globally, and 95% of all malaria deaths. Most cases and deaths occur in sub-Saharan Africa but half the world’s population is at risk of contracting this deadly disease. Kumar’s team developed two mRNA vaccines to disrupt different parts of the parasite’s life cycle.
The researchers immunized one group of mice with an mRNA vaccine targeting a protein that helps the parasites move through the body and invade the liver. They immunized another group of mice with a vaccine targeting a protein that helps parasites reproduce in a mosquito’s midgut.
“These vaccines were highly effective at preventing infection and they wiped out transmission potential almost entirely,” Kumar said.
The team also immunized mice with both vaccines together and found that co-immunization effectively reduced infection and transmission without compromising the immune response.
“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 said. “This study brings us one step closer to producing vaccines that can be used safely in humans to prevent illness and save lives—with the ultimate goal of defeating this disease.”