During the breakout session called "What's New in Infectious Disease Research in the Tropics," Epstein gave an update on NMRC's work with PfSPZ Vaccine, a whole organism vaccine comprised of aseptic, purified, radiation-attenuated, non-replicating, cryopreserved sporozoites. Sporozoites (SPZ) are one of the stages of the malaria parasite, which find their way to the liver after inoculation.
According to Epstein, the parasites induce a protective immune response without making copies of themselves. In other words, the weakened parasites do not replicate or get into the bloodstream, and thus do not lead to infection or disease.
"The studies on PfSPZ Vaccine are important because they bring us closer to having a malaria vaccine to prevent infection and disease in military personnel deployed to malaria-endemic regions as well as vulnerable populations residing in malaria-endemic regions," said Epstein. "Malaria has consistently been ranked as the number one infectious disease threat facing the military, and the burden of malaria remains incredibly high worldwide."
Epstein was the NMRC principal investigator (PI) on two PfSPZ Vaccine trials, published in Science in 2011 and the Journal of Clinical Investigation in 2017, respectively. The former trial was conducted in collaboration with the Center for Vaccine Development (CVD) at the University of Maryland in Baltimore (UMB); both trials were conducted in collaboration with Sanaria Inc. and the Walter Reed Army Institute of Research (WRAIR).
In mid-2017, Epstein also became the PI for the "Warfighter 2 Trial", conducted between 2016 and 2017. The trial was conducted at NMRC and CVD-UMB. Thirty subjects were immunized at each site. The participants had their screening visits, immunizations, and follow-up appointments at the NMRC Clinical Trials Center (CTC) in Bethesda, Maryland. Subjects were immunized with PfSPZ Vaccine and then, along with control subjects, underwent controlled human malaria infection by exposure to five bites from malaria-infected mosquitoes. Subjects were then followed closely to determine whether or not they developed malaria through the evaluation of blood smears and polymerase chain reaction (PCR). Infection was treated immediately with anti-malarial medication.
"In all trials, the vaccine has been demonstrated to have a very good safety and tolerability profile and has also been easy to administer," Epstein said. "Our focus now is to enhance the efficacy and practical use of the vaccine." Two of the most important parameters for malaria vaccine development are duration of protection and protection against non-vaccine strains.
In the "Warfighter 2" trial, NMRC researchers were able to demonstrate vaccine efficacy of 40 percent against a non-vaccine strain of malaria when assessed 12 weeks after the final injection, a marked improvement from the previous trials.
As the DoD's premier scientific meeting, MHSRS helps to facilitate the exchange of information between almost 3,000 attendees from around the world on health care topics relevant to the warfighter. This year's meeting was held at the Gaylord Palms Resort and Convention Center, Aug. 20 23, Kissimmee, Florida, and focused on medical innovation as a key factor in operational and mission readiness.
NMRC's eight laboratories are engaged in a broad spectrum of activity from basic science in the laboratory to field studies at sites in austere and remote areas of the world to operational environments. In support of the Navy, Marine Corps, and joint U.S. warfighters, researchers study infectious diseases; biological warfare detection and defense; combat casualty care; environmental health concerns; aerospace and undersea medicine; medical modeling, simulation and operational mission support; and epidemiology and behavioral sciences.
NMRC and the laboratories deliver high-value, high-impact research products to support and protect today's deployed warfighters. At the same time researchers are focused on the readiness and well-being of future forces.