Ebola vaccine for great apes shows promise, but ethical hurdles may block further research

Swallowing just a few drops of a new vaccine could protect against the deadly Ebola virus. The new immunization is not meant for humans, but chimpanzees and gorillas, for which Ebola is a devastating disease as well. Yet the vaccine may never reach these great apes. Further tests are all but impossible because of new ethical rules, the researchers charge.  Ebola is best known as a killer of people, but the virus also causes epidemics in wildlife. A 2006 study estimated that an outbreak in 2002 and 2003 in the Republic of the Congo claimed the lives of 5000 gorillas, but others have said the impact of the disease is hard to measure. Still, Ebola is a real and possibly growing threat to great apes, says epidemiologist Fabian Leendertz of the Robert Koch Institute in Berlin, who studies pathogens in nonhuman primates.   Walsh, who is currently investigating this issue with automated camera traps in the Republic of the Congo, admits that these are major problems. “There are Gambian pouched rats all over the forest, and the minute you put anything out, they eat it,” he says. “I have to find a way to get around that and that’s what I’m focusing on now.” But new U.S. rules on research with chimpanzees are another hurdle, Walsh says. Further improvements on the vaccine, for instance to prevent it from losing its activity in the tropical heat, would require another round of testing on captive animals. And that looks all but impossible at the moment, he says. Biomedical research on chimpanzees has been declining for years, and a new rule issued by the U.S. government in 2016 requires a permit under the Endangered Species Act. Although the rule still allows research on captive chimps if it benefits wild populations, the restrictions have made it too expensive to maintain chimpanzee groups for research, says Walsh, who cut his own vaccine study short when the rules took effect last September. Walsh has titled his paper “The Final (Oral Ebola) Vaccine Trial on Captive Chimpanzees?”