Recent news indicates that the Ebola virus is spreading throughout the northern region of the Democratic Republic of Congo, including one case in Mbandaka, a city with a population of 1 million. Many people will remember the outbreak in 2014 that led to more than 10,000 deaths in West Africa. In efforts to curb a new outbreak, the World Health Organization (WHO) is launching a vaccination campaign. So far, they have sent 4,000 doses of the vaccine called rVSV-ZEBOV, with another 4,000 doses soon to follow.
Clinical studies on rVSV-ZEBOV appear promising. A recent report in early 2017 tested the Ebola vaccine on around 4,000 humans and claimed that it was 100% effective. If this is true, Ebola could be fully eradicated once the vaccine becomes universally available. Some scientists have disputed their claim of 100% efficacy. Yet, little evidence could support this dispute.
If this vaccine curbs an Ebola outbreak, or eradicates Ebola, it could change the world. But how did we get to this vaccine? Through animal research, of course!
In 2003, the Public Health Agency in Canada filed a patent for the rVSV-ZEBOV vaccine. Research on macaque monkeys supported this patent, finding that it protected 100% of the monkeys from Ebola. A long history of animal research predated this work with macaques. For example, some of the first research on animals tested Ebola vaccines on guinea pigs (1980) and baboons (1994). Then, research in 2002 comparing rodents with non-human primates concluded that non-human primates were better models for measuring the efficacy of potential Ebola vaccines.
Importantly, chimpanzee research has been critical not only for the development of an Ebola vaccine for humans, but for the animals themselves who are extremely vulnerable to the disease. With mortality rates of 95% for gorillas and 77% for chimpanzees, it has been estimated that one-third of the great ape populations have been killed by Ebola since 1990. However, since the US enacted stricter rules on chimpanzee research in 2016, it may not be possible for this life-saving research to continue.
Additional research using monkeys continued to conclude that the rVSV-ZEBOV vaccination was effective. These additional studies led to clinical trials on humans which began in 2010. The studies also currently inform on active animal research, testing other Ebola vaccinations for the future. Some other approaches are also currently being tested in clinical trials. For example, an experimental treatment, called ZMapp, protected non-human primates and humans against Ebola in 2014. Unfortunately, ZMapp has not yet been approved for widespread use because the clinical trials in 2015 had low enrollment. Other experimental treatments for Ebola include; Brincidofovir, TKM-Ebola, and Monoclonal antibody therapy.
From rodents to monkeys, animal research has contributed to the development of rVSV-ZEBOV. Although it is impossible to find every animal study leading to the vaccination, it is clear that animal research has played a key role in developing this treatment. And, if the vaccine does curb an outbreak, tens of thousands of people will have animal studies to thank for saving their lives.
Justin Varholick and Amanda Dettmer