Families: Papillomaviridae and Polyomaviridae Flashcards
What are the main 2 outcomes of Papillomavirus infection?
- formation of benign warts
- hyperplastic epithelial proliferation of the skin or mucous membrane that can undergo malignant transformation
What is the structure of Papillomavirus like? What is its genome like?
non-enveloped, small, icosahedral capsid
single molecule of circular dsDNA associated with histones in chromatin-like complexes
What are the early and late open reading frames in Papillomavirus genome for?
EARLY: express regulatory proteins E1-E8 that a necessary for host cell transformation
LATE: express capsid proteins L1 and L2
What are the 4 steps of Papillomavirus pathogenesis?
- inoculation of epithelium of hand, foot, throat, or cervix
- local multiplication
- wart formation
- wart either resolves (latency) or transforms
What is the most common STI in humans? How do most people present? What are some other possibilities?
human papillomavirus (HPV)
body’s immune system is able to clear HPV within 2 years, so no symptoms develop
- genital warts
- cervical cancer
- mouth/throat infection
How is HPV-caused cervical cancer avoided?
recombinant virus-like particle vaccines
- Gardasil
- Cervarix
pap smear
surgery
How does Papillomavirus replicate within the epidermis?
STRATUM SPINOSUM: maintenance of viral DNA (episomal), with few copies per cell
STRATUM GRANULOSUM: early protein synthesis, DNA replication
STRATUM CORNEUM: late (capsid) protein synthesis, virus assembly and maturation
HPV lifecycle in epidermis:
What is the mechanism of Papillomavirus oncogenesis? How is the oncogenic potential of BPV determined?
NATURAL HOST (cattle + BPV) = self-limited neoplastic disease, including large fibrous skin warts
INCIDENTAL HOST (horse + BPV) = sarcoid
BPV transforms cells by inserting viral genome into the host’s genome, resulting in loss of cellular functions
presence of viral proteins E5, E6, and E7
How is Papillomavirus able to get into the skin? Where does primary infection start and how does it develop?
entry through skin abrasions or wounds
starts at the stratum germinaticum and proliferates, infecting other keratinocytes laterally in association with virus-induced delayed maturation
How is Papillomavirus infection classified?
heterogenous (affects multiple species
- human, bovine, cottontail rabbit, canine oral, equine, European elk, rabbit oral
How does Bovine Papillomavirus infection typically present? When does this appear?
growth of fibropapilloma (warts) on the skin of the head, neck, shoulders, back, venereal regions, and abdomen that begin small and nodular, and then grow rapidly into dry, whitish, cauliflower-like masses
about 2 months after exposure, may last over a year
What 2 kinds of Bovine Papillomaviruses cause bovine cutaneous papillomatosis? What lesions characterize each? What aged cows are most susceptible?
BPV-5: flat, rice-grain fibropapilloma
BPV-6: “frond” type teat
calves (sometimes over 2 years old)
What types of BPV are there vaccines created for?
BHV-1, 2, and 4
What are the 2 vaccine strategies against Bovine Papillomavirus?
- PROPHYLACTIC: prevent infection in those not affected yet with the whole virus (formalin-killed wart tissue suspension, virus-like particle) that’s ineffective against existing warts
- THERAPEUTIC: vaccination of animals infected with BPV-4 E7 or BPV-2 L2 to induce early regression of warts