Vaccines show promise in treating Ebola

Two experimental vaccines against the deadly Ebola virus ravaging West Africa could be available as soon as November. Ebola cAd3 and VSV-EBOV would first be given to health care workers most at risk

Ebola virus: Outer membrane is studded with glycoprotein (GP) which binds to host cell to enable infection

Ebola cAd3: Developed by U.S. National Institute of Allergy and Infectious Diseases (NIAID) and GlaxoSmithKline. 10,000 doses available by end of year

Vaccine uses genetically modified chimpanzee “cold” virus – chimp adenovirus type 3 (cAd3) – to deliver non-infectious Ebola GP gene to human cells. Gene produces glycoprotein that triggers immune system to fight viral infection

VSV-EBOV: Developed by Canada’s National MicrobioloY Laboratory. 800 doses of vaccinedonated to World Health Organization

Prime-boost vaccine: Netherlands-based Crucell and Denmark-based Bavarian Nordic, (J&J’s vaccine division) are working with NIAID to produce a two-shot, prime-boost vaccine

Vaccine based on weakened strains of vesicular stomatitis virus, a common animal pathogen. Glycoprotein of VSV is replaced with Ebola GP. Protects both before and after exposure. Profectus Biosciences is also developing a VSV vaccine

TKM-Ebola: Tekmira vaccine gave 100% protection in non-human primates to otherwise lethal dose of Zaire Ebola virus

First shot uses adenovirus-based vaccine to get harmless Ebola gene into cells to prime immune system. Second shot contains smallpox-based vaccine which boosts immune response

ZMapp: Vaccine developed by Mapp Biopharmaceutical has successfully treated five of seven Ebola victims – two fatalities

Vaccine uses RNA interference – known as RNAi – which silences disease by causing genes to block Ebola replication within cells of infected person

Cocktail of three genetically modified mouse monoclonal antibodies – molecules that neutralize GP protein on surface of Ebola virus

Sources: Pharmaceutical companies, Centres for Disease Control, Virology Blog