Navy developing several malaria vaccine approaches

The U.S. Naval Medical Research Center’s U.S. Military Malaria Vaccine Program is currently researching three malaria vaccine development approaches.

Malaria is endemic to most tropical regions of the world, as well as some subtropical areas that U.S. forces operate in, like Afghanistan and Korea. The USMMVP’s goal is to limit the ability of malaria to compromise the integrity of U.S. missions by sickening troops, according to Science.DODLive.mil.

Captain Thomas Richie, director of the Navy’s Malaria Program at the Naval Research Center in Silver Spring, Maryland, and the research coordinator of the USMMVP, said that naval research is following three vaccine development approaches, all of which target the early stages of infection.

The first target, according to Richie, is when the parasite first enters the human body and travels through the blood stream to invade the liver. The second target is when the parasite develops for five days or longer in the liver cells themselves, before the parasite breaks out of the liver and back into the blood stream in another form.

“These early stages of infection do not harm the body or cause any symptoms, so if a vaccine targets them effectively, it will completely prevent any manifestations of infection,” Richie said, according to Science.DODLive.mil. “It is the later stages that grow in the blood that cause the clinical syndrome of malaria, leading to anemia and prostration, and in the severe forms of the disease, to organ failure, coma and death.”

The first vaccine approach injects small quantities of key parasite proteins. These proteins are mixed with an adjuvant to induce high levels of antibody. The second approach involves injecting gene-based vaccines that induce strong immunity at the cellular level, a different form of the immune system from antibodies that are able to kill the parasites in the liver. The third approach is to inject live-attenuated parasites, using sporozoites - the stage in which the parasite was injected by the mosquito - that have been weakened genetically or through radiation.

“The highest protection, about fifty to ninety percent, has been achieved by immunizing with irradiated sporozoites that are delivered via the bites of mosquitoes, a cumbersome and time consuming vaccination process,” Richie said, Science.DODLive.mil reports.

Richie said that because there is no certainty as to which vaccine approach could yield the target of 80 percent effectiveness, the USMMVP also maintains a scientific program that is focused on the development of new antigens, exploring novel technologies such as bacterial vectors, identifying the means of immune-mediated protection and improved compounds capable of stimulating the immune system.

“Despite having very effective drugs to treat individuals suffering from malaria, I feel the most cost-effective measure to fight this disease is to develop preventive malaria vaccines,” Richie said, Science.DODLive.mil reports.