A team of scientists from a US medical centre have developed an equine flu vaccine which enables horses to be protected from flu, both now and in the future. The scientists from the University of Rochester Medical Center and Technology Departments, the University of Kentucky and the University of Glasgow Centre for Virus Research, chose to focus on improving the flu vaccine, which hadn’t been updated in 25 years, in order to help prevent a possible pandemic in people. The study results were published in Virology on an open access basis.
Signs of equine flu include a very high temperature, between 39-41C, a clear watery nasal discharge that may change colour to yellow or green and thicken, a clear discharge from the eyes and redness around the eyes, a frequent harsh, dry cough which can last for a number of weeks, swollen glands under the lower jaw, loss of appetite and depression, swelling of the lower limbs. The disease is very contagious among horses but cannot be spread to humans. Horses which contract equine flu should be placed in isolation and given rest. They should not attend horse shows, and a stable yard with an outbreak of equine flu, should put strict hygiene measures in place. The virus does not live long outside the host, but can be spread through contact with feed buckets or the people who care for the horse. Symptoms develop within 1-5 days of coming into contact with the virus.
The scientists were concerned that there .had been no new developments in equine flu vaccines for over 25 years, and the current vaccines did not protect against currently circulating strains of flu. They developed a live-attenuated vaccine, which was given as a spray up the nose and mimicked the development of an actual flu virus. The virus itself has been dampened down in the vaccine, so that it cannot cause the animal to get actual flu, however the scientists found that the vaccine caused a better immune response and a longer period of protection than other vaccines which used inactivated flu virus to provoke the immune system response.
The study was small: the vaccine was only tested on six horses and mice, and the scientists are currently planning to carry out a larger study. The way that the vaccine was created enables it to be updated easily and quickly so that it can also protect against future strains of flu. This has not previously been available in equine flu vaccines.
The scientists recognise that it is important to prevent the spread of flu in animals because they can be infected with a number of different strains, which could be mixed together to produce a new influenza strain. A new mixed strain of flu could be passed to people and cause a pandemic. This has happened before in the case of SARS and bird flu. New strains of flu are able to possibly cause a pandemic because it takes time to develop immunity.
Martinez-Sobrido, L., et al., Development of a novel equine influenza virus live-attenuated vaccine, Virology, March 2018, Vol.516, pp 76-85