Injected Ebola Vaccine

During my years of talking to park managers and ape conservationists about vaccinating wild apes, two concerns almost always popped up. First was the fear that the vaccine itself represented a serious health risk to wild gorillas. In some cases, this seemed to be prompted by a vague sense that vaccines were inherently dangerous. In other cases, the concern was very specific: that a “live” (replicating) vaccine would overwhelm the immune systems of wild apes who were already under immunological stress from so many other factors or even spill over into non-target species. Concern about the immunological fragility of wild apes was also central to the second concern, that any Ebola vaccine intended for use on wild apes should first be safety-tested on a captive ape.

To address these concerns, I went looking for a non-replicating vaccine that didn’t cause infection. This turned out to be one of the most positive aspects of my sojourn as an Ebola vaccine warrior in that many of the biomedical researchers then developing Ebola vaccines at the time were tickled to think that their vaccines could aid in the conservation of wild apes. After many discussions, I eventually landed with Javad Amman and Kelly Warfield at Integrated Biotherapeutics. Their virus-like particle vaccine wasn’t a fully replicating virus that could cause an infection, just a snippet of the viral coat protein: the part of the virus that is “learned” by the host’s adaptive immune system. Because they do not cause infection, such “subunit” vaccines are considered to be exceedingly safe within the vaccinated and individual and cannot transmit infection to other individuals.

To find trial subjects, I approached a large number of zoos. Almost all expressed solidarity with my goals but, off the record, said they couldn’t risk the public backlash of being labeled as modern-day vivisectionists for using their captive apes in vaccine trials. Many of the other obvious options, ape sanctuaries, were on record as being stridently against the use of captive apes in vaccine testing. So, I went to the only remaining option, biomedical laboratories with captive chimps. The New Iberia Research Center in Louisiana held the largest such population and had previously been the target of a sting operation by animal rights advocates. New Iberia was eager to demonstrate the major improvements it had made to the of it’s handling of its captive chimps, including large new outdoor closures in which chimps lived in persistent social groups. It agreed to do the trial at cost and subsequently donated blood workups on each of the study subjects.

Each of the chimps in the 2011 trial received two doses of the VLP vaccine separated by two weeks. None of the chimps exhibited any clinical, behavioral, or serological symptoms of serious adverse reaction to vaccination. And all of the study chimps subsequently developed robust antibody responses to Ebola virus antigen. This was the first trial in which captive chimpanzees were used to test a vaccine for use in the conservation of wild chimpanzees.