GlaxoSmithKline (GSK) reports that an Ebola vaccine candidate that it is co-developing with the US National Institutes of Health (NIH) , could be given to healthy volunteers in the UK, The Gambia, and Mali, as early as September as part of a series of safety trials of potential vaccines aimed at preventing the disease.

A £2.8 million ($4.6 million) grant from the Wellcome Trust, the Medical Research Council (MRC) and the UK Department for International Development (DFID) will allow a team led by Professor Adrian Hill of the Jenner Institute at the University of Oxford to start safety tests of the vaccine alongside similar trials in the US by the National Institute of Allergy and Infectious Diseases (NIAID), which his part of the US NIH. The Phase I trials will begin as soon as they receive ethical and regulatory approvals, which will be considered on an expedited basis. If approvals are granted, the UK research teams could start vaccinating volunteers from mid-September

The consortium's funding will also enable GSK to begin manufacturing up to around 10,000 additional doses of the vaccine at the same time as the initial clinical trials, so that if the trials are successful, stocks could then be made available immediately by GSK to the World Health Organization to create an emergency immunization program for high-risk communities. 

The vaccine candidate is against the Zaire species of Ebola, which is the one circulating in west Africa, and uses a single Ebola virus protein to generate an immune response. As it does not contain infectious virus material, it cannot cause a person who is vaccinated to become infected with Ebola. Pre-clinical research by the NIH and Okairos, a biotechnology company acquired last year by GSK, has indicated that it provides promising protection in non-human primates exposed to Ebola without significant adverse effects.

Safety trials with small groups of healthy volunteers are now required to ensure that the vaccine does not cause unforeseen side effects, and that it generates a good immune response to Ebola in humans before it can be rolled out to larger at-risk populations, even on an experimental basis. To accelerate these trials, the NIH has agreed to provide the NIAID/GSK Ebola vaccine for safety studies led by the Oxford team, which will run in parallel to its own trials. Oxford's Jenner Institute has extensive experience of clinical trials of similar vaccines, which they have evaluated clinically for six other diseases in Europe and Africa.

If the first volunteers vaccinated in the Oxford study show a good response with no adverse reactions, the trial will, after approval from the relevant authorities, be extended to volunteers at the MRC Unit in The Gambia. A second West African arm of the study, led by Professor Myron M Levine of the Center for Vaccine Development at the University of Maryland School of Medicine, and Professor Samba Sow of the Center for Vaccine Development in Mali (a joint initiative between the University of Maryland School of Medicine and the Ministry of Health of Mali), will then begin in Bamako, Mali.

NIAID is testing this same vaccine in the US, in addition to a related vaccine that is designed to protect against two Ebola species (Ebola Zaire and Ebola Sudan). It is hoped that the Phase I trials might be finished by the end of 2014, after which deployment of the vaccine could be fast-tracked should it prove to be safe and immunogenic.

The NIAID/GSK Ebola vaccine candidate is based on an attenuated strain of chimpanzee cold virus, called chimp adenovirus Type 3 (ChAd3). The adenovirus is used as a carrier, or vector, to deliver benign genetic material derived from the Ebola virus Zaire species that has caused the current Ebola outbreak in west Africa. The genetic material contained in the investigational vaccine cannot cause a vaccinated individual to become infected with Ebola. The vaccine candidate delivers the Ebola genetic material to human cells but does not replicate further. Rather, it allows the vaccine recipient's cells to express a protein, and that protein prompts an immune response in the individual.

Source: GlaxoSmithKline