A National Institutes of Health vaccine in development for Marburg virus has first-in-human data showing it induced antibodies against this pathogen that causes a potentially deadly infection with no approved treatments.

The data are from a small Phase 1 study. But the results are a step toward a vaccine for Marburg, a virus that comes from the same virus family as Ebola and causes similar hemorrhagic fever symptoms. The study results were published recently in the journal The Lancet.

The NIH vaccine candidate, called cAd3-Marburg, was developed at the National Institute of Allergy and Infectious Diseases’ Vaccine Research Center. It uses a modified chimpanzee adenovirus called cAd3 that can no longer replicate and cause infection. Engineered to display a protein found on the surface of Marburg virus, the vaccine is intended to induce an immune response to the pathogen. The vaccine platform on which cAD3-Marburg is based is the same technology the Vaccine Research Center used to develop experimental vaccines for Ebola virus and Sudan virus.

The dose-escalation study, conducted at the Walter Reed Army Institute of Research Clinical Trials Center, enrolled 40 healthy adults. The first three participants received the low dose. When no adverse reactions were observed after seven days, the study proceeded to dose the next 17 participants. The same procedure was followed for the high dose.

Results showed that the vaccine was well tolerated with no serious adverse events reported for either dose. A fever reported in one participant in the high dose group resolved the following day, the NIH said. On the measure of immune response, 95% of study participants exhibited a robust antibody response after vaccination; 70% of those participants maintained that response for more than 48 weeks.

Last summer, a Marburg outbreak declared in Ghana ended following the implementation of outbreak control measures. Ghana is one of the countries where the NIH vaccine will face its next clinical tests. Other locations include Kenya, Uganda, and the U.S. If clinical data from those studies supports the promising results seen in the Phase 1 trial, the cAd3-Marburg virus vaccine could someday be used in emergency responses to Marburg virus outbreaks, the agency said.

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