18. adenoviridae, papillomaviridae, polyomaviridae

what type of genome do papillomaviridae, polyomaviridae, and adenoviridae have? where do they replicate and how can they affect the host cell?

1. DNA

2. replicate in nucleus → mechanisms to induce S phase of cell

   • can transform cells (“DNA tumor virus”)

are papillomaviruses, polyomaviruses, and adenoviruses naked or enveloped?

naked → very stable in environment

what are the most medically important species papillomaviruses infect? are they zoonotic?

1. bovine > equine > canine

2. mostly species specific → not zoonotic

how are papillomaviruses transmitted?

• direct or indirect contact

• via wounds or abrasions

• sexual transmission

• spread via fomites

can shed without lesions

what type of diseases/clinical presentations do papillomaviruses cause?

• most cause self-limiting, benign warts

• some can cause tumors (inhibit tumor suppressors in cells)

• subclinical infections common

papillomaviridae pathogenesis

• wound/abrasion needed to access basal layer

• replication in stratified squamous epithelial cells

  • skin (keratinocytes)

  • mucous membranes (stratified squamous epithelium)

• induces cell division (hyperplasia) → papilloma

• virus life cycle coordinated with epithelial cell differentiation

  • DNA replication in basal layer → virus shedding in keratinized layer

what are the clinical signs of bovine papillomavirus? what is the distribution of the lesions?

• classic warts on skin

  • more common on head, neck, and shoulders

  • also on teats, penis, body

• **NOT pruritic or painful

• usually benign, regress spontaneously

• can interfere with function, milking, etc.

• large masses possible

what are predisposing factors to bovine papillomavirus?

• more common in calves and yearlings

• more common in winter & housed animals

can bovine papillomavirus be found on/in normal skin?

yes → persistent virus common with detection of DNA in normal skin

• trauma → virus replication & papilloma

what is the difference between papillomas and fibropapillomas?

• papillomas → epithelium

• fibropapillomas → epithelium + underlying dermal tissue

what types of tumors can bovine papillomaviruses cause? what is required for tumorigenesis?

• carcinoma of the GI tract

• hematuria and/or carcinoma of the urinary bladder

• both GI and bladder disease require co-carcinogen

  • BPV infection + bracken fern ingestion

how is bovine papillomavirus diagnosed?

• clinical appearance usually sufficient

• histopathology of lesion

  • IHC or EM

  • PCR → careful because BPV can be found in normal skin

• no virus isolation because cell culture system difficult

bovine papillomavirus treatment/control

treatment

• regress on their own in 1-6 months

• leave alone unless interfering with function

control

• prevent animal-to-animal and fomite spread

what two lesions can equine papillomavirus cause?

• papillomas (warts)

• aural plaques

what is the typical appearance of equine cutaneous papillomas? what is their distribution?

appearance

• benign warts

• multiple small, raised papillomas is typical (miliary pattern)

locations

• most common: lips & noses

• less common: eyelids, inner pinnae of ears, genitalia & legs

**not pruritic or painful

in what age group are equine cutaneous papillomas most common?

most common in young animals (1-3 years old)

what is the characteristic appearance of equine aural plaques?

• flat cutaneous lesion inside pinna

• can be very large

• benign

• not pruritic or painful

equine papillomavirus treatment/control

treatment

• warts regress on their own in 1-9 months → leave them alone!!

• aural plaques often don’t regress

• only perform surgery if interfering with function

control

• prevent animal-to-animal and fomite spread

what are sarcoids? what is their biological behavior?

• connective tissue tumors of horses and other equids

• can be locally aggressive, but do not metastasize and are benign

• can be persistent & recurrent

what are common locations for sarcoids?

head > neck/trunk/shoulders

• less common on ventral abdomen and legs

equine sarcoids are strongly associated with infection of what virus?

BPV (bovine papillomavirus)

sarcoid treatment

avoid treatment unless:

• interfering with normal function

• growing, ulcerating, chronic damage

what types of papillomas can canine papillomavirus cause?

oral, ocular, cutaneous

which type of canine papilloma is most common?

oral papillomas

where are canine oral papillomas typically located? what age group do they most commonly affect?

• location:

  • lips >>> inside cheeks, palate, tongue, oropharynx (esophagus)

• affect puppies or young dogs

  • usually < 6 months; up to ~2 years

where are ocular papillomas located? (canine papillomavirus)

cornea, conjunctiva

what are predisposing factors to cutaneous papillomas? (canine papillomavirus)

• older, often immunocompromised dogs

• rarely occurs with oral papillomas

how is canine papillomavirus diagnosed?

• clinical appearance, especially for oral papillomas in young dogs

• histopathology ± IHC

• PCR (interpret carefully because normal skin can be +)

canine papillomavirus treatment

• most regress on their own in 1-2 months → leave them alone

• if they don’t regress and are large, surgical excision BUT surgery is associated with recurrence

what species of bird is most severely affected by avian polyomavirus?

budgerigars (parakeets)

clinical signs of avian polyomavirus in budgerigars (parakeets)

• rapidly fatal “Budgerigar fledgling disease”

  • <10-15 days of age

  • SQ hemorrhages, CNS signs

• feather abnormalities (abnormal molt)

  • >15 days of age

how does avian polyomavirus present in other birds?

other psittacines & rarely other birds

• usually subclinical

• disease can occur:

  • peracute death in neonates

  • hemorrhagic, edema, pneumonia, or CNS disease

what are other differentials for abnormal feathers in parrots?

• sporadic abnormal molt (aka French molt)

  • excessive molting ± broken tail or wing feathers

• psittacine beak & feather disease virus (circovirus)

how is avian polyomavirus transmitted?

• feather dust

• feces

• respiratory secretions

• in ovo (budgies) → transmission to egg

avian polyomavirus control

killed virus vaccine

in general, how are adenoviruses transmitted?

direct contact or aerosol (shed in respiratory & other secretions)

what is another name for canine adenovirus-type 1?

infectious canine hepatitis

how is canine adenovirus-type 1 transmitted?

• virus is shed in urine, feces, & saliva

• transmission via direct contact with infectious materials or droplets (sniffing, eating, etc.)

  • enters nasopharynx, oropharynx, conjunctiva, etc.

canine adenovirus-type 1 pathogenesis

1. oronasal infection (tonsillar crypts)

2. draining lymph node infection

3. viremia

4. spread to liver & kidneys

5. possible spread to CNS

what types of diseases/clinical signs are associated with canine adenovirus type-1?

• acute disease → systemic infection

  • fever, abdominal pain, jaundice, vomiting, petechial hemorrhages and bloody diarrhea, anemia

    • hemorrhage → lack of clotting factors, endothelial cell damage, and DIC

    • severe hemorrhage = poor prognosis

  • CNS signs

    • hepatic encephalopathy in domestic dogs

    • (encephalitis in foxes; rarely domestic dogs)

• peracute death

  • no clinical signs

• mild or subclinical infection (persists in kidneys)

what causes “blue-eye” keratitis?

type III immune complex hypersensitivity

• immune complexes deposit in vessels of ciliary body → block fluid exchange → bilateral corneal edema

what is the difference between CAV-1 and CAV-2 modified live vaccine?

• CAV-1 MLV → “blue-eye” keratitis is common side-effect (same as natural infection)

• CAV-2 MLV → no blue-eye and simultaneous protection against both CAV-1 and CAV-2 (cross protection)

what type of disease does canine adenovirus-type 2 cause?

• local respiratory infection (not systemic)

• infectious laryngotracheitis (“kennel cough”)

canine adenovirus-type 2 clinical signs

dry, harsh, hacking cough

• ± fever, nasal discharge