Horses, like humans, are susceptible to infections by the influenza virus. And like other animals, horses are capable of spreading the flu to humans, so vaccinating these animals is important for controlling the flu. In a new study from the University of Rochester Medical Center, scientists present a new vaccine to protect horses from the flu.
Unlike past vaccines, the new vaccine was designed with a live-attenuated flu virus. This means that the vaccine incorporates a weakened form of the virus, a technique shown to trigger a better immune response and provide protection from infection for longer. This is opposed to more traditional vaccines that include inactivated or “dead” flu viruses. Vaccines for the measles, mumps, rubella, rotavirus, smallpox, chickenpox, and yellow fever all include a live-attenuated virus.
Live-attenuated vaccines are not without their potential dangers. People with suppressed immune systems, such as those with certain diseases, the elderly, young children and babies, and people who have recently received an organ transplant, could fail to produce an adequate immune response to the vaccine, developing an infection instead.
The vaccines is given as a spray through the nose, created using “reserve genetics,” a genetic engineering technique that allows the opportunity for scientists to easily and quickly update the vaccine to match new circulating strains of equine flu. The entry point is the nose so the immune system begins its response before the live-attenuated virus makes its way to the lungs, where it can cause disease.
Recent tests with the new vaccine showed that it was successful at protecting both mice and horses against the currently circulating H3N8 equine influenza virus. There were no adverse side effects observed.
Vaccinating horses is one way to limit the number of bodies through which the flu virus can spread, reducing the risk of the virus spreading among humans. In addition to horses, dogs and pigs can be infected with multiple strains of the flu virus, giving the virus a vessel for mutating and creating new strains that existing vaccines don’t protect against.
Almost all horses infected with the virus eventually show symptoms (nasal discharge, coughing, wheezing). An as many horses often travel for events and breeding, the opportunities for the virus to spread are many, making vaccination even more important. Going forward, researchers plan to do more studies with the vaccine to test its efficacy and safety.
The present study was published in the journal Virology.