Rhinopneumonitis

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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

Provide a physical and biochemical description of the organism. What kind of organism is it, what does it look like, how is it built, what are its metabolic properties, how can it be identified, what is it's life cycle, &c. In other words, describe the organism from its perspective.

Ecology (including pathogenesis)

Describe its habitat, symbiosis, and contributions to environment. If it is a pathogen, how does this organism cause disease? Human, animal, plant hosts? Describe virulence factors and patient symptoms.

Interesting feature

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References

[Sample reference] Takai, K., Sugai, A., Itoh, T., and Horikoshi, K. "Palaeococcus ferrophilus gen. nov., sp. nov., a barophilic, hyperthermophilic archaeon from a deep-sea hydrothermal vent chimney". International Journal of Systematic and Evolutionary Microbiology. 2000. Volume 50. p. 489-500.

http://www.petplace.com/horses/rhinopneumonitis/page1.aspx

http://books.google.com/books?id=3WvYMKmIvY8C&pg=PA1230&lpg=PA1230&dq=equine+rhinopneumonitis+classification&source=bl&ots=mYdSK7vWUo&sig=MjZFhH3XVojifsYFWBsSFQ3cqhg&hl=en&ei=o36tTpfnLOjj0QGZ7OyuDw&sa=X&oi=book_result&ct=result&resnum=7&ved=0CEkQ6AEwBg#v=onepage&q=rhinopneumonitis&f=false

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.