Herpes virus infection is a widespread disease. Fatal disease in horses. It is caused by equine herpesvirus 1 (EHV-1). This virus is very similar to human herpes viruses. This group includes viruses responsible for chickenpox, cold sores and genital herpes. The virus' ability to lie dormant undetected in an infected animal for years has doomed previous attempts to prevent its spread to failure.
Symptoms Spread Research Sources
The first symptoms are usually nasal discharge, loss of appetite, fever and swelling. The virus attacks the respiratory tract, reproductive organs and central nervous system, gradually spreading to the entire body. This can cause incontinence, inability to stand and stillbirths. Causing viral abortions in pregnant mares.
Nasal discharge, much like human sneezing, is an extremely effective way for the virus to spread. When many horses share the same food source or bridles are shared, the virus can be transmitted quickly. To contain the virus, stables are quarantined when there is a suspected case. However, the worst outbreaks often occur immediately after horse shows. At a show in the town of Ogden in the U.S. state of Utah, a large number of horses contracted a single case of equine herpes and each carried the virus to their home stables located in different states ANCHOR ANCHOR . This led to quarantines at the affected stables. A number of other cancelled equestrian events.
The virus is so widespread that most horses become infected with it, usually early in life. This illustrates the striking similarity to the herpes viruses that cause chickenpox and cold sores. With such a common virus, restrictions on movement can be. Regular testing does little ANCHOR .
The equine herpes virus, apart from horses, can also be transmitted to other hoofed animals. In 2010, two polar bears at a German zoo became infected with equine herpesvirus transmitted by an unknown route from zebras. While the infection appeared to be only latent in the zebras, it caused meningitis in the bears, which caused them to die shortly after being infected ANCHOR .
At the moment, research is working on the development of antiviral agents that prevent the virus from spreading further through the body. Although this strategy does little to prevent reinfection of horses, it could be an effective way to prevent the disease from developing into more than a respiratory illness ANCHOR .
The standard herpes virus drug called acyclovir, used to treat cold sores in humans, cannot be dosed high enough for effective action in a horse's bloodstream.
There are currently no vaccines that can completely prevent infection with EHV-1, although there are several that offer limited protection against certain aspects of the disease. The inactive vaccines Pneumabort K and Prodigy, for example, are marketed as protection against miscarriage in pregnant mares. Although the effectiveness of vaccines tends to last only a few months, some vaccines can reduce the likelihood of transmitting the virus to other horses, thus indirectly protecting them ANCHOR .
Another approach to combat EHV-1 is the use of short, single-stranded or double-stranded ribonucleic acid molecules (small interfering RNA, siRNA) ANCHOR . This method works by binding to special messenger substances, the messenger RNA. Messenger RNA instructs the cell to make a specific protein. In which this messenger RNA is intercepted, the protein is not formed and the virus can not function in a normal way. In 2009, scientists published a paper showing in mice that short stretches of ribonucleic acid molecules can be used to suppress virus replication and symptoms through simple topical administration ANCHOR . In this case, the proteins whose expression was prevented were glycoprotein B and Ori helicase, which are essential for entry into cells B and B, respectively. which are necessary for the replication of the genome. Due to the special conditions of this treatment method, it is very difficult for the virus to develop resistance. This method has since been tested in horses, where there has been a significant decrease in neurological complications from infections with EHV-1, although it appears that the method has little effect on the amount of virus in the body ANCHOR .