Rhinopneumonitis
A Microbial Biorealm page on the genus Rhinopneumonitis
Classification
Virus; Incertae sedis; Incertae sedis; Herpesvirales; Herpesviridae ; Varicellovirus; Equine Herpesvirus
Description and significance
Rhinopneumonitis, also called rhino, is an inflammation of the mucosa of the nasal cavities and lungs in horses. It is caused by the equine herpes virus and only affects horses. Almost all adult horses are infected due to natural exposure after birth. After infection, the virus hibernates in the lymph nodes of the respiratory system and the horse is infected for the rest of its life. Whether or not the horse exhibits symptoms of the disease depends on the strength of the immune system. The immune system keeps the virus in check and if it is busy with other diseases or problems affecting the horse, the virus can escape its confinement. Rhino is similar to the human herpes virus in this way because of its capability of latency and relapse. Symptoms of the repiratory disease caused by the virus include: fever, hacking cough, nasal discharge, enlarged lymph nodes in the neck, and stocking up and heat in the lower legs. Respiratory disease is the most common illness caused by the virus, but the virus can also cause abortion in brood mares. Vaccinations against herpes viruses are not very effective because the virus lives in the horse and affects its immune system. However, vaccinations are most important for brood mares to protect them against viral abortion. Minimal protection is vaccinating once a year. To prevent respiratory disease in young horses requires administration every 2-3 months and to prevent abortion, mares should be vaccinated three times during gestation.
Genome structure
The Rhinopneumonitis virus is composed of large, 150 kb, double-stranded DNA genomes that are enclosed within a protein capsid and surrounded by a delicate lipid envelope containing a dozen different glycoproteins. The virus's chromosome is circular. Because the envelope is so delicate, the survival of the virus in the environment is very limited and makes them highly susceptible to destruction by common disinfectants. EHV-1 and EHV-4 strains of rhino contain 76 homologous, co-linear genes.
Cell structure, metabolism & life cycle
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Ecology (including pathogenesis)
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Interesting feature
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References
http://www.petplace.com/horses/rhinopneumonitis/page1.aspx
http://www.ivis.org/special_books/Lekeux/allen/IVIS.pdf Allen, G.P. "Respiratory Infections by Equine Herpesvirus Types 1 and 4". Equine Respiratory Diseases, P. Lekeux (Ed.) 2002. International Veterinary Information Service.
