Malaria Vaccine Development Branch
Among the traditional laboratories in NIAID’s Division of Intramural Research, the Malaria Vaccine and Development Branch (MVDB) looks like it belongs more at a private biotechnology firm than on a research campus.
MVDB was commissioned to research, develop, and produce prototype malaria vaccines and conduct early-phase clinical trials of promising vaccine candidates. As such, it boasts an organizational structure aimed at effective vaccine development strategy. Currently, there is no vaccine to prevent malaria, though it is responsible for more than one million deaths each year, according to the World Health Organization.
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| Diagram of malaria life cycle. The NIAID Malaria Vaccine Development Branch is developing a vaccine for each stage. Source: NIAID |
Units within MVDB focus on distinct steps of the vaccine development process, which include identifying potential immunity-inducing agents, or antigens, for future research; generating research and production clones that serve as vaccine foundations; developing fermentation and purification processes to prepare vaccines for clinical trials; providing quality control; formulating the vaccines for clinical trials; evaluating preclinical trials in animals; and testing the candidate vaccines in humans. Within each unit are specialists who contribute expertise to their respective steps in the process.
This organizational structure allows MVDB to develop several vaccine candidates at the same time, devoting proper attention and resources to each. One candidate need not complete the process before a new one can receive the branch’s resources, making the process both efficient and rapid.
MVDB is currently developing strategies for three kinds of malaria vaccines: asexual blood-stage, transmission-blocking, and pre-erythrocytic-stage. An asexual blood-stage vaccine will elicit immune responses capable of either destroying malaria parasites in the human bloodstream or inhibiting parasites from infecting red blood cells. In either case, the effect is to reduce or prevent parasitic infection.
Transmission-blocking vaccines (TBVs) prevent transmission of malaria by blocking the infection of mosquitoes when they take a blood meal. If the mosquito does not ingest the parasite from one human, it cannot transmit the parasite to another. TBVs are likely to have their greatest impact in areas of relatively low disease transmission, such as South America and Southeast Asia, but are unlikely to reduce the prevalence of infected humans in areas of high transmission, such as sub-Saharan Africa.
Pre-erythrocytic-stage vaccines prevent disease-causing agents from taking hold of human liver cells. The pre-erythrocytic stage, or the stage in the liver, precedes the blood stage, when most malaria symptoms appear. Stopping the parasite in the liver will prevent progression of the disease to the blood stage and thus to clinical symptoms. An effective pre-erythrocytic-stage vaccine will prevent the symptoms of malaria in humans and disrupt malaria transmission. Even a partially-effective vaccine will reduce the parasite burden in the liver, leading to a substantial reduction in frequency and severity of disease.
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