First human trial for experimental Marburg virus vaccine reports success

Promising results have been published from the first human trial testing an experimental vaccine targeting the deadly Marburg virus. Flagged as a potential pandemic-causing virus, this is the first Marburg vaccine to move into Phase 2 human trials.

Coming from the same Filoviridae family of viruses as Ebola, Marburg is just as deadly as its better-known cousin, albeit slightly less virulent. The virus first emerged in 1967, with a handful of outbreaks in Europe causing a deadly hemorrhagic disease. Subsequent genomic studies traced its origins back to Uganda and Kenya.

Since its emergence, there have been more than a dozen outbreaks over the past 50 years, most recently emerging last year in Ghana for the very first time. However, Marburg's frightening fatality rates of up to 90% led infectious disease experts to warn of the virus's significant future pandemic potential.

"… previous Marburg virus outbreaks in the Democratic Republic of the Congo (1998–2000) and Angola (2004–05) demonstrated that in particular settings, such as conflict areas with weak health infrastructure, outbreaks can remain uncontrolled for months or years, claiming hundreds of lives," said Daniela Manno, from the London School of Hygiene and Tropical Medicine, in the recent editorial for The Lancet. "It is possibly only a matter of time before a large Marburg virus outbreak occurs."

Unlike Ebola, which has both monoclonal antibody treatments and an effective vaccine, there are no approved therapies or vaccines for Marburg virus disease. This has led global vaccine charity Gavi to identify Marburg as a major future pandemic concern.

This new Marburg vaccine, dubbed (cAd3-Marburg), uses an adenovirus vector to deliver a Marburg glycoprotein. Primate studies published last year showed a single dose of the vaccine generated a protective immune response in animals lasting up to one year.

A recent Phase 1 human trial enrolled 40 healthy adults to receive the experimental vaccine. The cohort showed the vaccine was well-tolerated with no serious adverse effects. Significant immune responses were also detected in 95% of subjects, persisting in 70% across the entire 48-week follow-up period.

The US government has recently invested several million dollars in moving this Marburg vaccine research forward. Subsequent human trials are now being planned in Ghana, Kenya, Uganda, and the United States.

Source: NIH