Dr Neil Bryant from the AHT, who is leading the research, said: "EHV is a major welfare concern for horses and foals and causes emotional, as well as financial strains, on horse owners and breeders around the world. It can strike any horse at any time so a vaccine will be of global welfare benefit to all horses, including the thoroughbred and sports horse breeding industries, and would help control this serious and sometimes fatal disease."
As a viral infection, EHV can cause respiratory disease, abortion or fatal illness in new born foals and neurological disease in adult horses, with signs ranging from slight wobbliness through to complete paralysis. The disease can strike any horse at any time because the virus, like other herpesviruses (such as the cold sore virus in humans), becomes dormant within most horses early in their life. It then re-emerges when the animal is later stressed such as when transported or mixed with new horses. A seemingly healthy pregnant mare may suddenly, and without warning, abort her unborn foal or may show signs of respiratory disease including mild fever, coughing and discharge from the nose. A horse which appears fit and well may suddenly show abnormalities when walking and within hours may be unable to stand.
Despite the potential severity and impact of outbreaks, there is still no vaccine that is licensed to protect against the neurological form of the disease and abortions still occur in highly vaccinated horse populations. The AHT says protection afforded by existing vaccines currently in use is sub-optimal, something that was highlighted by the 2016 abortion storm in Hertfordshire in fully vaccinated animals.
Neil added: "We have become aware of a pressing need for progress towards a new and improved EHV-1 vaccine. Just last month, the AHT was again called upon to work with the racing industry and affected parties in dealing with confirmed cases of EHV-1 abortion in premises in Yorkshire and Suffolk."
To that end, the charity has now established the Equine Industries EHV Vaccine Steering Group. Chaired by Professor Joe Brownlie of the RVC, the steering group includes world-renowned experts on both human and equine herpes viruses from a number of research establishments, who have concluded that the most appropriate way forward is for the AHT to design a modified live virus (MLV) vaccine.
After securing funding from a large number of organisations, including the Alborada Trust, EBM Charitable Trust, Horserace Betting Levy Board and the Racing Foundation, Paul Mellon Estate, Thompson Family Charitable Trust, Coolmore Ireland, Newsells Park Stud, Thoroughbred Breeders’ Association and Juddmonte Farms, the AHT has begun its five-year research programme.
Neil added: "We’re at the beginning of a very exciting and potentially ground-breaking vaccine development. Through our research, we will construct different viruses with attenuating mutations and assess their suitability as MLVs. We hope our findings will enable further development by vaccine manufacturers in creating an effective vaccine to protect against the serious clinical signs induced by EHV-1."
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