A new Ebola vaccine candidate has been announced by Emergent BioSolutions; the candidate has a booster in the form of a modified virus and is set to start clinical trials (phase 1) in the United Kingdom shortly. The modified virus the vaccine is based on is a version of a chimpanzee adenovirus (ChAd3) vaccine that was produced by GlaxoSmithKline in conjunction with the National Institute of Allergy and Infectious Diseases. The ChAd3 vaccine contains a modified vaccinia Ankara vector (MVA EBOZ). The MVA vector could potentially boost T cell responses as well as antibody levels.
The phase 1 trials are to be led at the Jenner Institute in Oxford, and they have been designed to test what the safety of the vaccine is. MVA EBOZ is made in an avian cell line and removes the necessity for eggs as well as adds consistency to the manufacturing process, and could also increase the number of doses delivered.
There is also a phase two/three trial of ChAd3 vaccine (unboosted) which uses VSV-EBOZ, a vesicular stomatitis virus, to deliver a segment from the Ebola gene. It is currently underway in Liberia, with a vaccination trial of VSV-EBOZ to be launched soon in Guinea.
It has been said that different strategies and vaccines are needed to battle Ebola; questions of dosing and scale-up options are difficult to answer however, with the declining infection levels in outbreak countries.
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