GlaxoSmithKline and Merck will test new Ebola vaccines in West Africa this month. They're racing to cure this disease that causes severe hemorrhagic fever in humans and other mammals. To date, Ebola has claimed more than 8,600 lives and infected more than 20,000 people in Sierra Leone, Liberia and Guinea.
These vaccines have shown promise in preliminary safety trials involving animals and could eventually save the lives of thousands of people worldwide. Animal research is vital to the study of disease, and it is the primary reason why scientists have hope that they'll be able to cure Ebola and other emerging infectious diseases.
Scientists rely on animal models to learn about disease processes and develop potential treatments. In order to see how a disease progresses, researchers must use a living system with a genetic makeup similar to humans. Mice, the most popular model for disease research, have over 92 percent genetic similarity to the human genome. Nonhuman primates, such as chimpanzees, are 98 percent genetically similar to humans.
The information gleaned from the study of disease progression in animal models is invaluable and cannot be replaced by cells grown in a dish or by computer models.
For decades, ethicists have agreed that animal studies must precede human trials. This principle is at the heart of the Nuremberg Code, a guideline for research ethics adopted in the aftermath of World War II, when doctors conducted heinous experiments on concentration camp prisoners. The Food and Drug Administration does not allow clinical drug trials in humans without prior safety and efficacy testing of the drugs in animals.
Animal research has enabled scientists to stamp out several major epidemics of infectious disease over the past century. Researchers eradicated smallpox globally with a vaccine developed in cows. Thanks to decades-long vaccine research in monkeys, dogs and mice, the world is essentially rid of polio.
Nonhuman primates have also contributed to the research and development of drugs that fight cancer, malaria, HIV/AIDS, hepatitis and Alzheimer's. The U.S. survival rate for cancer increased by more than 60 percent between 2001 and 2007 thanks in no small part to novel treatments produced through animal-based research.
More recently, animal research has helped stop potential international threats such as avian flu and SARS. Animal models have enabled researchers to better understand these diseases and how they spread. As a result, they've been able to contain them and avert global pandemics.
Then there's the recent, rapidly escalating fight against the Ebola virus. An anti-Ebola serum called ZMapp was made from antibodies harvested from mice exposed to parts of the virus. The serum has been credited with saving the lives of two American aid workers who tested positive for the virus. Researchers first found the treatment effective for monkeys infected with Ebola virus — and then began administering it to humans. The FDA has already offered $42 million to the company that developed ZMapp to speed up production.
Other potential Ebola cures developed in animal models include Tekmira Pharmaceuticals' TKM-Ebola injection which has proven effective against high doses of the virus in monkeys. And Chimerix, a Durham, North Carolina-based life-science firm, is working with the Centers for Disease Control and Prevention and the National Institutes of Health to test its Ebola antiviral brincidofovir in animals.
Humans are not the only animals susceptible to Ebola. Wild primates including chimpanzees and gorillas are extremely susceptible, with fatality rates as high as 95 percent. The virus has killed as many as one-third of the world's gorillas and chimpanzees in the past few decades in Central Africa. If scientists were to discover a cure for the deadly virus, they could conceivably save the lives of wild apes — many of whom are endangered.
To beat Ebola as we've overcome other global epidemics, officials must preserve access to animal research. Cures for this deadly pathogen — and thousands of lives — depend on it.