Glaxo's Ebola vaccine passes key animal test as human trials begin

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Scanning electron micrograph of ebolavirus in an African green monkey kidney cell--Courtesy of NIAID

Ebola vaccine research is moving ahead at lightening speed thanks to combined public and private sector efforts, with GlaxoSmithKline ($GSK) unveiling fresh data showing that its experimental jab protected monkeys in a preclinical study.

With human safety trials beginning this month at the National Institutes of Health, the Glaxo results are promising, but they comes with a catch--the vaccine's effectiveness wanes over time, so the jab would likely require a booster shot after the initial inoculation.

In a study conducted alongside the National Institute of Allergy and Infectious Diseases Vaccine Research Center, scientists found that one dose of the vaccine protected all four macaque monkeys that were exposed to high levels of ebolavirus 5 weeks after being vaccinated. The research was published Sept. 7 in Nature Medicine.

The vaccine was initially effective, but the protective effects of the single shot decreased over time. In another conducted 10 months after vaccination, only two out of four monkeys survived infection of Ebola when being exposed to the virus.

Another group of four macaques was given the vaccine plus a booster vaccine containing ebolavirus gene segments incorporated into a different vector 8 weeks later. These animals were exposed ebolavirus, but unlike the previous group, all four animals that received both doses of the vaccine did not develop Ebola symptoms, suggesting that a booster shot could increase protection.

The experimental vaccine--which GSK acquired the experimental vaccine in May 2013 in the $325 million buyout of Okairos--uses a chimpanzee cold virus vector containing two ebolavirus gene segments. The vaccine works by entering a cell and delivering the new genetic material, which in turn causes a protein to become expressed, eliciting an immune response in the body.

Two other Ebola vaccines are lining up to be tested in clinical trials soon. NewLink Genetics' ($NLNK) vaccine has gotten the regulatory green light to go ahead with human studies, and another by Johnson & Johnson ($JNJ) and Danish company Bavarian Nordic is set to begin clinical trials in early 2015.

Meanwhile, the death toll from the current Ebola outbreak in West Africa has topped 2,200 people, and the World Health Organization estimates that as many as 20,000 may become infected.

- get the abstract from Nature Medicine

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