Flashcards in Exam 2 - Family: Papillomaviridae Deck (21):
Family: Papillomaviridae - Properties
Non-enveloped, spherical, 55 nm, single molecule of circular double-stranded DNA, Resistant viruses.
Produce papillomas (warts) on the skin and mucous membranes of most animal species.
Family: Papillomaviridae - Replication
Linked intimately to the growth and differentiation of cells in stratified squamous epithelium of the skin and some mucous membranes. Infect keratinocytes in the basal layer of the epithelium. The viral genomes are replicated in synchromy with cellular DNA.
Benign oncogenic papillomaviruses
The DNA is episomal, meaning it is not integrated into the host cell DNA and persists as an autonomously replicating episome
Malignant oncogenic papillomaviruses
The viral DNA is integrated into that of the host. Thus, integration probably is necessary for malignant transformation. Involve oncogenes E6 and E7.
1. Bovine papillomavirus
2. Canine Oral Papillomatosis
3. Equine sarcoids
Oncoproteins in Papillomaviruses
Papillomavirus (HPV) E6 and E7 proteins. DNA damage signals p53 to cell death. HPV causes E6 which prevents p53 from making damaged DNA commit suicide. HPV also causes E7 to bind to Rb and prevents its from stopping damaged cells from growing.
Bovine Papillomatosis - Host
More commonly seen in cattle than in any other domestic animal. Natural bovine papillomavirus infection of horses may occur after exposure of the horses to cattle.
Bovine Papillomatosis - Transmission
Virus is transmitted between animals by contaminated milking equipment, halters, nose leads, grooming and earmaking equipment, etc. Sexual transmission of venereal warts in cattle.
Bovine Papillomatosis - Fibropapilloma
Mostly caused by bovine papillomavirus types 1,2, and 5. A fibrous core covered to a variable depth with stratified squamous epithelium, the outer layers of which are hyperkeratinized.
Bovine Papillomatosis - Fibropapilloma - Young bulls
Fibropapillomas are found frequently on the penis, but not on prepuce. Wart grows rapidly and may surround tips of penis. This may render them of no value as bull studs.
Bovine Papillomatosis - Cutaneous papillomas
Bovine papillomaviruses type 3. Lesions lack fibrous core.
Bovine Papillomatosis - Bracken fern
Bovine papillomatosis type 4. Ingestion of the bracken fern cause invasive carcinoma of the alimentary tract. Bracken fern contains carcinogens, mutagen, and immunosuppressive chemicals. In cattle that eat bracken fern, papillomavirus types 1 and 2 may also contribute to the syndrome of "enzootic hematuria" that is characterized by hematuria and/or urinary bladder cancer.
Bovine Papillomatosis - Treatment
Surgical excision or cryosurgery with liquid nitrogen. Topical agents, podophyllin and undiluted medical grade DMSO. Bovine interferon alpha, podophyllin plant, wart vaccine.
Canine Oral Papillomatosis
The warts usually begin on the lips, and can spread to the buccal mucosa, tongue, palate, and pharynx. Later may become roughened and cauliflower-like. Do not extend below epiglottis or into esophagus.
Canine Oral Papillomatosis - Koilocytosis
Characterized histologically by epithelial hyperplasia and cytoplasmic vacuolization
Canine Oral Papillomatosis - Clinical signs
Halitosis, hemorrhage, ptyalism, discomfort. Ocular warts.
Canine Oral Papillomatosis - Treatment
Surgical excision, cryosurgery, electrosurgery. Autogenous vaccine ( a wart is removed, made into a crude vaccine, and injected into the same animal) may be tried. Efficacy doubtful.
Most common neoplasm in horse, locally invasive benign fibroblastic skin tumor, associated with bovine papillomaviruses 1 or 2. Sarcoids do not metastasize. they may persist for life. Are locally invasive, recur after surgical removal
Equine Sarcoids - Transmission
Flies as vectors, fomites, breed susceptibility with major histocompatibility complex has been defined.
Equine Sarcoids - Susceptible horses
American Quarter horse