Ebola Vaccine with Philadelphia Roots Moves Toward Human Trials
On Monday, September 22, in Philadelphia, Matthias J. Schnell, PhD, of the Jefferson Vaccine Center, announced that one of his lab's Ebola virus vaccine candidates was moving into human trials. Funding from the National Institute of Allergy and Infectious Diseases and the Department of Defense will allow production of a clinical lot of the vaccine for a Phase 1 trial that could be completed as early as mid-2015 (see Anthony Fauci's testimony to the House Foreign Affairs Committee).
Schnell addressed a gathering of diplomats, scientists, and a large audience of students and healthcare professionals at Thomas Jefferson University to discuss the Ebola epidemic in West Africa. Ambassadors of Sierra Leone, Ivory Coast, and Guinea spoke about the difficulties of epidemic response in their countries, which are especially complex given the legacies of years of civil unrest there.
WIth these challenges and the skyrocketing number of Ebola infections in the region, a vaccine is desperately needed. Schnell's vaccine uses a killed rabies virus platform to deliver key antigens from Ebola virus. So far, the vaccine has been tested in vitro, in small mammals, and in non-human primates. The results have been promising: high antibody titers were measured in vaccinated animals. (Schnell noted that the vaccine's protection derives largely from antibody response and not from T-cell responses.) An earlier version of the inactivated vaccine given to non-human primates protected half of the animals after challenge with the virus (see those results in this 2013 PLoS Pathogens study). However, a newer version of the vaccine protected 100% of vaccinated and later challenged non-human primates (Schnell, personal correspondence, 9/24/2014).
Other Ebola vaccines have been advanced with support from NIAID:
- A GSK vaccine that uses a chimpanzee adenovirus as a vector is in a Phase 1 trial at the NIH Clinical Center.
- Another similar GSK vaccine will begin a Phase 1 trial in the United Kingdom and in Mali in October.
- An Ebola vaccine using vesicular stomatitis virus (a virus in the same family as the rabies virus) as a vector developed by the Public Health Agency of Canada is scheduled to begin Phase 1 testing this fall.
Another crucial problem in the Ebola crisis centers on identifying cases so as to properly care for those infected and prevent transmission to others. E. Solange Ngazoa Kakou, PhD, a microbiologist at the Pasteur Institute in Ivory Coast, spoke at the Jefferson symposium about the diagnostic tools available at her lab, including reverse transcriptase PCR and nested PCR to detect Ebola virus RNA in serum, plasma, and urine samples. These tools were financed in large part by the US Centers for Disease Control and Prevention. The Bill & Melinda Gates Foundation recently announced a $50 million grant, part of which will go to improving diagnostic tools for use in the epidemic.
We'll be following news from the clinical trials of the Ebola vaccines in the months to come.