What is equine herpesvirus-1?
In horses, equine herpesvirus-1 (EHV-1) has been studied intensely because of its ability to cause two main problems. Firstly, it can lead to abortion during the late stages of pregnancy. Secondly, it can lead to neurological disease, which results in horses staggering as they walk and, in severe cases, being unable to get up.
Both outcomes are distressing for the horse as well as its owner. This virus also causes respiratory disease, in which horses develop cold-like symptoms but recover quickly with rest and nursing. Vaccines are available against EHV-1, providing some protection against disease, but they’re only partially effective and outbreaks still occur. It’s also impossible to predict which horses will succumb to the disease and why others develop resistance.
Our research and its impact
Here at Nottingham, our research has focused on understanding how the virus moves through the body, from the nasal passages to the pregnant uterus.
We’ve also investigated the immune responses that help protect horses against the virus. Our research showed that these involved both antibody and specialised white blood cells called cytotoxic T lymphocytes. We were also able to identify the viral proteins that stimulate these immune responses.
The next step was to develop a pilot vaccine, proving the principle that it was possible to vaccinate horses with these viral proteins and give partial protection against respiratory disease and abortion. We believe that if this vaccine can protect against abortion, it should be protective against neurological disease as well.
As part of our ongoing investigations, we want to identify risk factors that pre-dispose a pregnant mare to abortion if she is exposed to EHV-1. By identifying these risk factors, it may be possible to prevent the abortion by careful management. We have some preliminary evidence that the genetic make-up of the horse is likely to be a factor and are currently seeking grant funding to support further work.