Advancing the development of a malaria transmission-blocking vaccine

Three leaders in malaria vaccine development announced today a collaboration to evaluate a potential vaccine candidate designed to prevent transmission of malaria from mosquitoes to humans—a type of vaccine that researchers think could contribute to the eventual eradication of malaria.

The partners—the PATH Malaria Vaccine Initiative (MVI), the National Institute of Allergy and Infectious Diseases (NIAID) and the Johns Hopkins Bloomberg School of Public Health Center for Immunization Research (CIR)—are working together to conduct a Phase 1 clinical trial in healthy adults to assess the safety and immunogenicity of the protein Pfs25 in a conjugated vaccine developed at NIAID. This new partnership was announced at a presentation at the 60th annual meeting of the American Society of Tropical Medicine and Hygiene.

Pfs25 is one of the transmission-blocking vaccine (TBV) approaches that aim to block transmission of malaria from mosquitoes to humans by preventing the malaria parasite from developing in the mosquito. While such vaccines would not directly protect an immunized individual from developing clinical malaria, they would reduce the chances that other individuals in the community get malaria by preventing the spread of infection by the mosquito.

Malaria kills nearly 800,000 people per year, most of them children under age five in Africa. Defending against the disease has been challenging: both the parasite and its mosquito host are highly adaptive and have survived for millennia. While drugs and insecticides have had a significant impact on the burden of disease, resistance on the part of the parasite and mosquito poses an ongoing challenge. A TBV would work in synergy with these interventions, since blocking transmission of the parasite would reduce the pressure on other measures, thereby slowing the development of resistance and thus extending their effectiveness.

“This is the first clinical trial supported by MVI to use a transmission-blocking approach,” said Ashley Birkett, PhD, director of research and development at MVI. “This is the first step in what is typically a long process of evaluation. Nonetheless, we are excited by the potential of TBVs to significantly limit the spread of malaria infection. Eradication of malaria may be decades away, but we believe a successful TBV—used alongside safe and effective drugs, insecticides, bednets, and possibly a malaria vaccine that protects the individual against infection and disease—would be essential to achieving that goal.”

“The Pfs25 vaccine and other transmission blocking vaccines are unique in their approach in that they target a key stage of the malaria parasite's lifecycle rather than attempting to build immunity to malaria in humans,” said Kawsar Talaat, MD, clinical principal investigator and assistant scientist at the Bloomberg School. “We'll need many tools to defeat malaria and an effective transmission-blocking vaccine could go a long way toward achieving that goal.”

About the PATH Malaria Vaccine Initiative: MVI is a global program established at PATH through an initial grant from the Bill & Melinda Gates Foundation. MVI’s mission is to accelerate the development of malaria vaccines and ensure their availability and accessibility in the developing world. MVI’s vision is a world free from malaria. For more information, please visit www.malariavaccine.org.

About PATH: PATH is an international nonprofit organization that creates sustainable, culturally relevant solutions, enabling communities worldwide to break longstanding cycles of poor health. By collaborating with diverse public- and private-sector partners, PATH helps provide appropriate health technologies and vital strategies that change the way people think and act. PATH’s work improves global health and well-being. For more information, please visit www.path.org.

About the Johns Hopkins Bloomberg School of Public Health: As a leading international authority on public health, the Johns Hopkins Bloomberg School of Public Health is dedicated to protecting health and saving lives. Every day, the School works to keep millions safe from illness and injury by pioneering new research, deploying its knowledge and expertise in the field, and educating tomorrow's scientists and practitioners in the global defense of human life. For more information, visit: www.jhsph.edu.

About the JHSPH Center for Immunization Research: The Center for Immunization Research (CIR) is a leader in vaccine evaluation and Good Clinical Practice (GCP) training. Established in 1985 by Dr. Mary Lou Clements-Mann, the CIR is one of the nation’s leading vaccine research centers. CIR investigators primarily conduct Phase 1 and 2 clinical trials of new vaccine candidates in the United States and in less-developed countries. For more information, please visit: http://www.jhsph.edu/cir/.

About the National Institutes of Health: NIH, the nation's medical research agency, includes 27 Institutes and Centers and is a component of the US Department of Health and Human Services. NIH is the primary federal agency conducting and supporting basic, clinical, and translational medical research, and is investigating the causes, treatments, and cures for both common and rare diseases. For more information about NIH and its programs, visit http://www.nih.gov/.

About the National Institute of Allergy and Infectious Diseases: NIAID conducts and supports research—at NIH, throughout the United States, and worldwide—to study the causes of infectious and immune-mediated diseases, and to develop better means of preventing, diagnosing and treating these illnesses. News releases, fact sheets, and other NIAID-related materials are available on the NIAID Web site at http://www.niaid.nih.gov/.