Promising results for Phase I live-attenuated Ebola vaccine

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A vaccine candidate against Ebola virus (rVSVΔG-ZEBOV-GP) has demonstrated promising results in Phase I randomized controlled trials, including safety, tolerability and high antibody titres post-vaccination.

The devastating 2013–2016 Ebola outbreak sparked a large amount of research into developing a vaccine and recent outbreaks in the Democratic Republic of Congo have again highlighted the need for this preventative measure. This study, published recently in the Canadian Medical Association Journal, reports on an attenuated recombinant vaccine candidate comprised of vesicular stomatitis virus expressing Zaire Ebolavirus glycoprotein.

The candidate, termed rVSVΔG-ZEBOV-GP, was developed at the Canadian National Microbiology Laboratory of the Public Health Agency of Canada (Ottawa, Canada). The recent trial included 40 healthy individuals aged 18–65 and aimed to assess the safety and immunogenicity of the vaccine.

The participants were divided into four groups of 10 individuals, one group received a placebo and the other 3 received varying doses of the vaccine. The researchers carried out follow-up appointments over 180 days, discovering that any adverse effects were mild to moderate and reporting that there were no safety concerns after a single vaccine dose.

The researchers also used ELISA to demonstrate that the vaccine induced protective immunity, demonstrating persistent, high antibody titres at 180 days post-vaccination. In addition, the team indicated that the optimum dose of rVSVΔG-ZEBOV-GP appeared to be 20 million pfu.

First author, May ElSherif (Canadian Center for Vaccinology, Ottowa, Canda) commented: “The results of this trial were positive and very promising; all 3 dose levels of the VSV [vesicular stomatitis virus]Ebola vaccine were well-tolerated by participants, and no safety concerns were identified.”

The vaccine will now be assesses in two sites in Africa, where Ebola virus is endemic, in addition to Montréal and Ottawa in Canada. These upcoming studies will test the safety and effectiveness of the vaccine candidate in HIV-patients.

Sources: Elsherif MS, Brown C, MacKinnon-Cameron D et al. Assessing the safety and immunogenicity of recombinant vesicular stomatitis virus Ebola vaccine in healthy adults: a randomized clinical trial. CMAJ. 189(24)(2017); www.eurekalert.org/pub_releases/2017-06/cmaj-evd061317.php

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