10 Questions
What is the characteristic of koilocytes in papillomavirus infections?
They are enlarged keratinocytes.
Where does viral production occur in papillomavirus infections?
Superficial layers
How does HPV infection evade the immune system?
It hides from the immune system.
What is the primary mode of transmission of HPV?
All of the above.
What is the estimated prevalence of HPV infection in the United States?
At least 20 million Americans infected.
Which HPV types are associated with cervical cancer?
HPV-16 and HPV-18.
What is the characteristic of common warts caused by HPV?
They are benign and self-limited.
What is the characteristic of oral papillomas caused by HPV?
They are pedunculated and have a rough surface.
What is the risk factor for HPV infection and cancer progression?
All of the above.
What is the estimated percentage of cervical cancers associated with HPV?
99.7%.
Study Notes
Papillomaviruses
- There are over 100 types of papillomaviruses, classified into 16 groups (A to P) based on tissue specificity
- Cutaneous HPV and mucosal HPV are two types, with a group of mucosal HPV being oncogenic
- Papillomaviruses have a capsid with 72 capsomeres, arranged in an icosadeltahedron
- Replication cycle is linked to keratinocytes and other epithelial cells, accessing cells in basal layers through breaks in superficial layers
Characteristics of Papillomaviruses
- Stimulate cell growth, which facilitates viral replication
- Different nuclear factors induce transcription of viral genes (viral maturation) in the stratum granulosum
- Virus is produced in stratum granulosum and released in stratum corneum (outermost layer)
Pathogenesis and Transmission
- Infection of skin epithelium → Warts
- Infection of mucosae (oral, genital, conjunctivae) → Papilloma
- Mode of transmission: close (direct) contact, fomites, and vertical transmission (mother-baby)
- Prevalence and incidence: possibly the most common sexually transmitted infection (STI) worldwide
Epidemiology
- At least 20 million Americans infected and around 6 million new genital cases per year
- Identified in 99.7% of all cervical cancers (HPV16 and HPV-18 account for 70% of them)
- HPV-6 and HPV-11 cause condyloma acuminatum, and oral and laryngeal papillomas
- Risk factors for infection and cancer progression: promiscuity, smoking, family history of cervical cancer, and immunosuppression
Clinical Syndromes
- Common warts: benign-self-limited skin proliferation
- Head and neck tumors: single oral papillomas, most common benign tumors of oral cavity
- Clinical characteristics: pedunculated, rough surface, papillary appearance, solitary, and recurrence is rare after surgical treatment
Diagnosis and Treatment
- Diagnosis: DNA molecular probe, PCR, Real-time PCR analysis (no culture)
- Treatment: removal (if painful or for cosmetic reasons), medical treatment: stimulators of inflammation and innate immunity (imiquimod, interferon), antivirals (cidofovir)
- Prevention: avoid contact with infected tissue, condom use may prevent transmission, immunization (tetravalent, nine-valent, and divalent vaccines)
Adenoviruses
- Genome: double-stranded DNA
- Structure: non-enveloped, capsid with 240 capsomeres
- Replication: 32-36 hours, around 10,000 virions
- Initiation of infection: attachment of viral fiber proteins to a glycoprotein belonging to the Ig superfamily of proteins
This quiz covers the diagnosis and treatment of papillomaviruses, including the characteristics of warts, detection methods such as PAP smears and molecular probes, and treatment options. It also touches on the spontaneous regression of warts.
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