MONDAY, SEPTEMBER 26, 2016

Study shows Ebola, Marburg DNA vaccines safe

A recent phase 1 trial in Africa showed that two experimental DNA filovirus vaccines to prevent Ebola virus and the closely related Marburg virus are safe.

The study also found that the vaccines produced similar immune responses in healthy Ugandan adults as in healthy U.S. adults earlier this year.

The findings of the study are published in The Lancet.

"This is the first study to show comparable safety and immune response of an experimental Ebola vaccine in an African population," lead author Dr. Julie Ledgerwood from the National Institutes of Allergy and Infectious Diseases (NIAID) at the National Institutes of Health, said. "This is particularly encouraging because those at greatest risk of Ebola live primarily in Africa, and diminished vaccine protection in African populations has been seen for other diseases."

Scientists from the NIAID developed the filovirus vaccines from the Zaire and Sudan strains, and the Marburg virus protein. The vaccines are comprised of proteins on the outer surface of the virus where immune responses against the proteins are highly protective in non-human primate models.

"These findings have already formed the basis of a more potent vaccine, delivered using a harmless chimpanzee cold virus, which is undergoing trials in the USA, UK, Mali and Uganda in response to the ongoing Ebola virus outbreak,” Ledgerwood added.

In the trial, the Makerere University Walter Reed Program enrolled 108 healthy adults between 18 and 50 years old from Kampala, Uganda, between November 2009 and April 2010. Each volunteer was randomly given an intramuscular injection of either the Ebola vaccine (30 volunteers), Marburg vaccine (30), both vaccines (30) or placebo (18) at the start of the study, four weeks later and then eight weeks later.

The vaccines given separately and together were safe and elicited an immune response by neutralizing the antibodies and T-cells against the virus proteins. Four weeks after the third injection, 57 percent of the volunteers had an antibody response to the Ebola Zaire protein as did 47 percent of the participants who received both the Ebola and Marburg vaccines. The antibodies then returned to undetectable levels within 11 months of the vaccination.

Both DNA vaccines were well tolerated with only one serious adverse event (neutropenia) in a Marburg vaccine-only recipient, but it was not thought to be vaccine-related.

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