Difference between revisions of "Papomaviridae"

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=Introduction=
 
Papillomaviruses infect keratinized cells, giving rise to sarcoids, warts, and papillomas.
 
 
 
=Morphology=
 
*Medium-sized, icosahedral, non-enveloped dsDNA viruses
 
 
 
=Virulence and Pathogenesis=
 
*Target actively-dividing cells
 
*Warts: genes expressed are associated with '''transformation''' (hyperplasia and delayed maturation)
 
*Virus is shed as cells exfoliate
 
*Oral papillomas in young animals often resolve spontaneously
 
 
 
=Epidemiology=
 
*'''Resistant''' viruses: can persist in environment for months
 
*Restricted to stratified squamous and mucosal epithelia with slow growth
 
*Usually species specific
 
 
 
=Types and Subtypes=
 
 
 
 
 
=Virus by Species=
 
===Canine Papillomavirus===
 
*Occur in oropharynx of puppies aged 4-6 weeks
 
*Usually resolve spontaneously
 
 
 
===Bovine Papillomaviruses===
 
*2 groups:
 
#Fibropapillomas: viral DNA sequences, but no virus found
 
#Epithelial Papillomas: virus found
 
*Calves most commonly affected
 
*Usually resolves spontaneously
 
*Can undergo malignant transformation to alimentary carcinomas
 
**Usually concurrent with grazing bracken (co-carcinogen) and ingesting quercetin (immunosuppressant)
 
*Can cause squamous cell carcinoma of the eye in Hereford cattle, where UV light acts as the co-carcinogen
 
 
 
===Equine Papillomaviruses===
 
*Occurs in horses aged 1-3 years
 
*Muzzle, oral cavity
 
*Spread by direct contact
 
*Virus persists giving life long immunity and antibody-detection
 
*Usually resolves spontaneously but can be treated by laser or cryo-freezing
 
 
 
===Equine Sarcoids===
 
*Most common '''untreatable tumor'''
 
*Locally aggressive tumor of integument
 
*Associated with Arabs and Thoroughbreds
 
*Thought to be associated with '''bovine papillomaviruses'''
 
*Virus entry through skin abrasions
 
*Flies may act as mechanical vectors
 

Revision as of 10:44, 22 May 2010