NIH launches first human trial of Ebola vaccine

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Nov 18, 2003 (CIDRAP News) – The National Institutes of Health (NIH) today announced the start of the first human trial of a vaccine for Ebola virus infection, a currently untreatable disease that kills most of its victims.

The vaccine, a version of which protected monkeys from the virus in a previous trial, will be tested for safety and for its effects on the immune system, according to a news release from the NIH's National Institute of Allergy and Infectious Disease (NIAID). A volunteer at the NIH Clinical Center in Bethesda, Md., received the first injection in the trial today. The vaccine does not contain any infectious material from the virus, officials said.

The announcement of the trial comes a day after the World Health Organization reported 11 cases of Ebola hemorrhagic fever in the Congo. Ebola outbreaks have grown more common in recent years, the NIAID said. The disease was first identified in 1976, but then disappeared until 1995.

In the announcement, NIAID Director Anthony S. Fauci, MD, said, "An effective Ebola vaccine not only would provide a life-saving advance in countries where the disease occurs naturally, it also would provide a medical tool to discourage the use of Ebola virus as an agent of bioterrorism."

The candidate vaccine is a component of a vaccine that fully protected monkeys from a normally lethal Ebola virus dose in a trial 3 years ago, the NIAID said. The candidate is a DNA vaccine, similar to other experimental vaccines that hold promise for controlling AIDS, influenza, malaria, and hepatitis. It was designed by researchers at the NIAID's Vaccine Research Center (VRC).

The NIAID said 27 volunteers between the ages of 18 and 44 will participate in the trial. Six will receive a placebo injection, and 21 will receive the vaccine. After getting three injections over 2 months, the participants will be followed for a year. Researchers will assess the vaccine's safety and examine the participants' blood for signs of immune system reaction to it.

The vaccine is made by Vical, Inc., of San Diego, which has secured a nonexclusive license from the NIH to proprietary gene sequences used in the vaccine, the NIAID said. The company said the license gives it the right to commercialize the vaccine if it proves effective and is licensed by the Food and Drug Administration.

The DNA vaccine is made using modified, inactivated genes from Ebola virus. "This gives the immune system information about viral structures so that it can mount a rapid defense should the real virus ever be encountered," the NIAID said. Barney Graham, MD, PhD, of the VRC said the virus was not present during any phase of manufacturing of the vaccine.

Researchers expect that the vaccine will ultimately be the first stage of a two-stage vaccination strategy called prime-boost, the NIAID said. In this approach, the DNA vaccine would initially "prime" the immune system. Later, the immune system would be boosted by a second inoculation with modified, non-disease-causing cold viruses that make selected Ebola proteins. "The booster essentially sets the immune system on alert against future infection by Ebola proteins," the agency said.

In August, VRC Director Gary Nabel, MD, PhD, and colleagues reported that the booster vaccine alone completely protected a group of monkeys from Ebola virus. The booster injection was tested alone to see if it could provide the rapid protection that would be needed in an Ebola outbreak. While the booster by itself triggers a fast immune response, the full prime-boost strategy "elicits a stronger immune response and is important to pursue for individuals at high risk, such as health care workers," the NIAID said.

Nabel said expanded clinical trials of Ebola vaccines using the prime-boost strategy could begin in 2005.

See also:

NIAID's Nov 18 news release

NIAID's Aug 6, news release on the trial of the booster vaccine in monkeys

World Health Organization's Nov 17 statement on Ebola cases in the Congo

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