As 400,000 lives are still lost every year due to malaria, researchers in Seattle are fervently working on a vaccine. Dr. Stefan Kappe and Dr. Jim Kublin, both faculty members at the University of Washington School of Public Health, say there could be a malaria vaccine in the next 10 years – but significant hurdles remain, including funding.
[Photo: r. Jim Kublin (left) and Dr. Stefan Kappe (right)]
“In short, it takes about $1 billion to get a vaccine to market,” said Dr. Kublin, a clinical associate professor in the School’s Department of Global Health. He and Dr. Kappe, an affiliate professor in the department, are working on the vaccine candidate at the Center for Infectious Disease Research.
Malaria is a life-threatening disease caused by parasites transmitted to people through the bites of infected female Anopheles mosquitoes. In 2015, 91 countries had ongoing malaria transmission, according to the World Health Organization (WHO). Globally, WHO estimates that in 2015, 214 million clinical cases of malaria occurred, and 438,000 people died of malaria, most of them children in Africa.
In conjunction with the novel malaria vaccine, Dr. Kappe and Dr. Kublin are working on new methods to test the vaccine in people, including an assay that can detect the malaria parasite in low levels in the liver before people get sick. They are also collaborating with the Fred Hutchinson Cancer Research Center and Kaiser Permanente for clinical facilities to see and monitor the trial participants.
The vaccine originated in 2005 from a $15 million Grand Challenges grant from the Bill & Melinda Gates Foundation and continued funding from the Department of Defense and the National Institutes of Health.
The researchers created a concept vaccine candidate by genetically attenuating malaria parasites (GAP). The attenuated parasite dies in the liver before reaching the bloodstream and causing malaria infection. This essentially teaches the immune system how to respond to future infection. The initial vaccine candidate was tested for safety on six people, but one got sick after the assay, so the researchers re-engineered it by removing an extra gene in the mosquito. That vaccine candidate was then tested with 10 people, where volunteers received 200 mosquito bites. No one was infected, indicating that the vaccine candidate is both safe and elicits an immune response that could effectively prevent infection. The results were published in January of this year in the journal Science Translational Medicine. A second human trial with 16 subjects is scheduled to launch in the fall to test efficacy.
The GAP vaccine theory is that eliminating three genes from the parasite may prevent the parasite from infecting a human and causing the disease, while challenging the immune system to provide future immunity. Mice inoculated with antibodies from the human volunteers have shown long-lasting immunity.
Since delivery of a malaria vaccine via mosquito bites is not practical, a biotech company in Maryland called Sanaria will be creating an injectable version. New human clinical trials could start testing the injectable vaccine in two to three years from now, said Dr. Kappe.
While other vaccines are being tested, none so far provides 100 percent protection – less than 50 percent protection is common, said Dr. Kappe. The scientists hope that their vaccine candidate will be significantly more effective.
Because malaria causes so much illness and death, the disease is a great drain on many national economies. Since many countries with malaria are already among the most resource-constrained nations, the disease maintains a vicious cycle of disease and poverty.