Papillomaviridae & Polyomaviridae (Exam 2)

Question 1

What are general characteristics of papillomaviridae?

Answer 1

Double-stranded
Circular DNA genome
Small icosahedral virus
Non-enveloped
Durable in the environment
Resistant to heat, UV light, low pH, disinfectants
Etiologies of warts and tumors

Question 2

How are papillomaviruses replicated?

Answer 2

Early (E) genes: regulate replication (oncoproteins)
Late (L) genes: encode structural proteins

Question 3

What is the pathogenesis of papillomaviruses?

Answer 3

Virus penetrates the skin and infects basal stem cells
Long incubation period
Early (E) virus gene products stimulate the proliferation of the basal cells
Hyperplasia leads to acanthosis
Late (L/structural) proteins are expressed in the stratum spinosum
Virions assemble in terminally differentiated keratinocytes

Question 4

What diseases are caused by bovine papillomatosis?

Answer 4

Tropism for keratinocytes = papillomas
Tropism for keratinocytes and dermal fibroblasts = fibropapillomas
BPV1,2,3 = fibropapillomas
BPV2: bladder neoplasms, enzootic hematuria associated with bracken fern (quercetin) ingestion
BPV4: papillomas in the GI tract, neoplasms
BPV5,5: papillomas on teats

Question 5

How is bovine papillomatosis transmitted?

Answer 5

Direct contact with warts on other cattle, virus on fomites and inoculation through skin or mucosae

Question 6

How is bovine papillomatosis shed?

Answer 6

Keratinized skin cells from warts

Question 7

What is the immunity associated with bovine papillomatosis?

Answer 7

Papillomas: spontaneous regression in 1 to 9 months, CTLs are important in regression of warts, lifelong immunity to the specific type of BPV
Aural plaques: persist for years

Question 8

What diseases are caused by equine papillomatosis?

Answer 8

Cutaneous papillomas, warts on the muzzle, ears, eyelids, genitalia in young horses
Aural plaques flat, depigmented, nodular in the inner surface of the pinnae

Question 9

How is equine papillomatosis transmitted?

Answer 9

Direct contact with warts or fomites
Aural plaque viruses, mechanical transmission by insects

Question 10

How is equine papillomatosis shed?

Answer 10

Keratinized skin cells from warts

Question 11

What immunity is associated with equine papillomatosis?

Answer 11

Papillomas: spontaneous regression in 1 to 9 months, CTLs are important in regression of warts, lifelong immunity to the specific type of BPV
Aural plaques: persist for years

Question 12

How is equine papillomatosis prevented and controlled?

Answer 12

Viruses are durable on fence posts, stable walls, halters, clippers, other fomites
Worts are a recurring problem on young horses raised in contaminated premises
Careful sterilization of equipment used on affected animals prior to use on others
Efficacy of autogenous vaccines and miscellaneous ointments are uncertain

Question 13

Describe equine sarcoids caused by papillomaviruses

Answer 13

Common neoplasm in horses
Fibroblastic tumor
On head, limbs, ventral body
Usually first observed in horses 3-6yrs of age

Question 14

What is the host range canine papillomatosis?

Answer 14

Canidae
All ages
Possible breed predisposition

Question 15

What symptoms are caused by canine papillomatosis?

Answer 15

Oral papillomas
Edophytic papillomas
Pigmented cutaneous plaques (pugs)
Squamous cell carcinoma, x-linked severe combined immunodeficiency

Question 16

How is canine papillomatosis transmitted?

Answer 16

Direct contact with warts on other dogs or fomites

Question 17

What immunity is associated with canine papillomatosis?

Answer 17

Warts common in young animals
Sudden regression of warts after few wks-yrs
Removal of one wart may be followed by regression of others, or coincidental
T cell immunity is important in wart regression
Immunity is type specific

Question 18

What vaccines are utilized for canine papillomatosis?

Answer 18

Experimental vaccines utilizing recombinant technology to produce capsid proteins L1 which form virus-like particles
95-100% protection against challenge in canine oral papillomavirus model
Autogenous whole-cell vaccines are reported to be efficacious in cattle but may cause tumors in dogs

Question 19

What symptoms are associated with passerine papillomavirus? What species?

Answer 19

Chaffinches
Papillomas on feet, “tasselfoot”

Question 20

What symptoms are associated with psittacine papillomavirus?

Answer 20

Papillomas, proliferative lesions in mucosa
Association with biliary and pancreatic adenocarcinoma
Cloacal papillomas may not be related to papillomavirus infection

Question 21

How is avian papillomavirus controlled?

Answer 21

Stable in the environment
Shed in dander and scales
Not very contagious
Long incubation period
Isolate affected birds
Clean up and disinfect cages, pens, fomites, destroy fences

Question 22

What are the general characteristics of polyomaviridae?

Answer 22

Double stranded
Circular DNA genome
Small icosahedral virus
Non-enveloped
Prototype = SV40
Pathogens of birds and humans

Question 23

How is polyomaviridae replicated?

Answer 23

Uptake in endosomes, release of genome
Transport to nucleus
Expression of early (LT, ST) transcripts
Translation in cytoplasm, transport to nucleus
LT stimulates transcription of late genes
LT initiates viral DNA synthesis
LT binds to p53 and RB, induces cell cycling

Question 24

What is the etiologic agent of budgerigar fledging disease?

Answer 24

An avian polyomavirus

Question 25

What is the host range of budgerigar fledging disease?

Answer 25

Budgerigars, parrots, macaws, lovebirds, Moluccan cockatoos, cockatiels, finches, kookaburras, chickens, falcons, and buzzards

Question 26

What symptoms/diseases are associated with budgerigar fledging disease?

Answer 26

Acute systemic disease in fledglings with high mortality
Dystrophic feather “french molt” in budgerigars
Hepatitis, mortality in other psittacines

Question 27

How is budgerigar fledging disease transmitted?

Answer 27

Ingestion, inhalation

Question 28

How is budgerigar fledging disease shed?

Answer 28

In feather dust, feces, urates, nasal and crop secretion

Question 29

How is budgerigar fledging disease prevented and controlled?

Answer 29

Viruses are durable on fomites and the environment
Maintained closed flocks
Avoid contact between wild birds and breeding stock
Depopulate, decontaminate, re-stock

Question 30

What is the clinical presentation of budgerigar fledging disease in budgerigars?

Answer 30

1 to 3 week old budgerigars
Sudden death, 30-80% mortality
Abdominal distension
Hemorrhage, reddening of skin
Ataxia
Dystrophic feathers
Inapparent infections

Question 31

What is the clinical presentation of budgerigar fledging disease in non-budgie psittacines?

Answer 31

3 to 14 week old non-budgie psittacines
Sudden deaths
Hemorrhagic diathesis: bruising, hemorrhage, anemia
Anorexia and weight loss
Elevated liver enzymes
Polyuria and diarrhea
CNS signs