Experimental Vaccine Protects Primates Infected with Ebola

September 8, 2014
Davy James, Associate Editor

Progress made on new Ebola drugs as US government pledges resources to West Africa.

While the US government has promised to send military resources to fight the spread of the Ebola virus in Africa, an experimental vaccine has exhibited promising results in protecting primates from the disease.

In a study published online September 7, 2014, in Nature Medicine, researchers evaluated the efficacy of a vaccine that acts similarly to an experimental treatment co-developed by the National Institutes of Health (NIH) and GlaxoSmithKline (GSK), which recently began human testing, as well as another drug in development by Johnson & Johnson that is projected to begin clinical testing in early 2015.

For the study, researchers evaluated the efficacy of the ChAd3 Ebola vaccine in eliciting rapid protection in monkeys. The drug was found to protect all 4 macaque monkeys 5 weeks after inoculation with high levels of the Ebola virus.

The 4 monkeys were inoculated initially with the ChAd3 vaccine, and then again 2 months later with a booster vaccine that contained viral gene segments of Ebola incorporated into a different vector.

The researchers were able to demonstrate durable protection from a prime-boost regimen after all 4 primates were fully protected from infection with high doses of the virus 10 months after initial inoculation.

The candidate drug is based on an attenuated strain of a chimpanzee cold virus, which is used as a carrier to deliver benign genetic material derived from a strain of the Ebola virus. The material contained in the vaccine does not cause an infection; rather, it delivers viral genetic material to human cells without further replication, allowing the recipient’s cells to express a protein that generates an immune response.

The Phase 1 trials for the drug are anticipated to conclude by the end of the year, while deployment of the drug could be fast-tracked if the vaccine is determined to be safe and immunogenic, the NIH said.

Meanwhile, in light of a death toll that has climbed above 2000 and nearly 4000 confirmed and suspected cases in West Africa, US President Barack Obama said Sunday on NBC’s Meet the Press that the country will step up relief efforts for the region, including military equipment and support for international health care workers.

Without support, Obama noted, the virus could mutate to become more transmissible, which could represent a serious health threat to the United States and the rest of the world.

“We’re going to have to get US military assets just to set up, for example, isolation units and equipment there to provide security for public health workers surging from around the world,” Obama said in a report published in the Washington Post.

The announcement followed a dire warning last week from Doctors Without Borders that the window to stop the virus from becoming a global biological disaster is rapidly closing.

“The clock is ticking and Ebola is winning,” said Doctors Without Borders International President Joanne Liu, MD, in a press release. “The time for meetings and planning is over. It is now time to act. Every day of inaction means more deaths and the slow collapse of societies.”