Equine arteritis virus

Equine Arteritis Virus

Equine Arteritis Virus (EAV) belongs to the genus Arterivirus, family Arteriviridae of the order Nidovirales (1). EAV viral particles have an icosahedral capsid that is around 30-35 nm in diameter and also have an envelope surrounding this capsid. Temperature and pH affect the stability of EAV viral particles. While at room temperature EAV viruses are stable for 24hs, at temperatures around -70°C viral particles canbe stored for many years. On the other hand at pH lower than 3, EAV viral particles are rapidly inactivated and lose their ability to infect susceptible cells.

Horses and donkeys are susceptible to EAV infection. EAV is not transmitted to humans so this disease is not considered as a zoonosis concerning human health. EAV infections are usually subclinical so no symptoms of infections can be detected. The clinical signs of the disease vary widely depending on the EAV strain involucrate in the infection. They are characterized by respiratory disease, conjunctivitis, pneumonia and abortion (2).

After the exposure of horses to EAV, they develop antibodies which protect them from re-infection. Although stallions and mares change their serologic status to positive, only stallions can spread viruses after the infection. The reason is that EAV could infect testicle cells and could be stored there for many years. In the same conditions that have not been yet elucidated, the EAV virus could be reactivated and eliminated by the horse’s semen. This is the reason why carrier stallions could be a natural reservoir of EAV (3).

In the equine industry, EAV is widely distributed in all countries. In Argentina, Equine Viral Arteritis was an exotic disease until 2010. This year in an equine farm, many symptoms were associated with EAV so after the intervention of SENASA to avoid the spread of this disease, vaccination was approved in Argentina.

(1) Snijder EJ, Meulenberg JM. The molecular biology of arteriviruses. J Gen Virol. . (1998) 79: 961-979. (2) Jones TC. Clinical and pathologic features of equine viral arteritis. J. Am. Vet. Med. Assoc. (1969) 155: 315-317. (3) Chirnside ED. Equine arteritis virus: an overview, Brit. Vet. J. (1992) 148: 181–197.