Papilloma and Polyoma

Polyomaviridae and Papillomaviridae morphology?

Isometric

Types of Papillomas

• Papillomavirus-induced papillomas(warts) - common in YOUNG and most SPONTANEOUSLY resolve

• Non-viral papillomas - Benign neoplasms in OLDER animals and DO NOT spontaneously resolve

What other viruses can cause papillomas or warts?

Herpes viruses

Diagnosis of Papilloma virus

• Histological exam

• Immunohistochemistry(proteins)

• PCR(NA)

  • Isolation(difficult to do)

Polyomaviruses

Formerly named as Papovaviridae

Polyomaviruses

• Used for the discovery of the polio vaccine

• Causes cancer in rodents

• Causes neurological disease in lab primates(monkeys)

• Most infections in mamals result in no disease except for birds

  • Highly host specific

Alphapapillomavirus

human papillomavirus (HPV) 32*

Betapapillomavirus

HPV 5*, 9, 49

Deltapapillomavirus

European elk papillomavirus, 2*

Bovine papillomavirus 1

Ovine papillomavirus 1

Epsilon papillomavirus

Bovine papillomavirus 5*

Etapapillomavirus

Fringilla coelebs papillomavirus

Gammapapillomavirus

HPV 4*, 48, 50,60,88

Iotapapillomavirus

Mastomys natalensis papillomavirus

Lambdapapillomavirus

Canine oral papillomavirus

Morphology of Papilloma and Polyomavirus

• non enveloped

• Spherical

• Composed of 72 six sided capsomeres arranged in 5 sided arrays

Genome and Viral proteins

• circular dsDNA

• L1,L2 proteins - forms capsid(structural proteins)

  • E1 to E8 - form non structural proteins for regulation and replication

Virions resistant to X insults and X survives lipid solvents, detergents, low pH, high temperatures

Virions resistant to environmental insults and infectivity survives lipid solvents, detergents, low pH, high temperatures

Virus Replication

• Virus replication linked to growth and

  differentiation of cells in stratified squamous

  epithelium (from basal layer to top layer)\

• Microtrauma(sugat) starts infection

  • Cell entry: basement membrane keratinocytes

  • Viral genome and E proteins enter cell nucleus

  • Production of copies of viral genome in episome form

  • Productive virus replication during terminal differentiation of host cell

  • Cell normally stops dividing upon terminal differentiation but it is prevented by the E protein so virus can complete its replication

  • Papilloma forms by increasing the keratinocyte replication

Immune response to infection

• Virus minimizes the innate immuse system recognition by not causing cell lysis and by only producing viral antigen in superficial layers of epidermis(S.granulosum)

  • Vaccines attack the virus but does not trigger cell mediated immunity. No papilloma regression

During replication, polyomavirus DNA is transcribed from X strands, whereas papillomavirus DNA is transcribed from X strand

During replication, polyomavirus DNA is transcribed from both strands, whereas papillomavirus DNA is transcribed from one strand

Cattle papillomavirus

• Warts more commonly found than other species

• common in calves and yearlings

• transimitted by fomites(contaminated milking equipements and more)

• Venereal warts through sexual transmission (can be avoided by AI)

• Warts occur 6 wks after infection

• Persist 1-6 months then regress(CMI mediated)

• Rarely Florid infection can occur

Oral canine papillomavirus

• most common papillomavirus in dogs

• typically affects young dogs

• lips, buccal mucosa, tongue, palate and pharynx

  • develop 4-8 weks after infection

Feline papillomavirus

• rare in cats

Budgerigar fledgling disease

• bird polyomavirus

• abnormal/poor feather growth

• depression, hemmorhage, anorexia, weight loss, ataxia, diarrhea and death

• hepatitis