Questions and Answers
What is the causative agent of genital warts?
The virus causing genital warts belongs to the ______ family.
Papovaviridae
What type of HPV causes 90% of external anogenital warts?
Low-risk HPV types 6 and 11
Which HPV types are considered high-risk and associated with invasive cervical cancer?
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What antibody class is detected in patients with regressing warts?
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HPV can be grown in vitro.
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Where are common sites for HPV lesions in men?
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What is the average incubation period for symptomatic lesions of HPV?
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Which proteins are involved in the oncogenic transformation related to HPV?
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Where are common sites for HPV lesions in women?
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Study Notes
Genital Warts and HPV
- Genital warts are caused by human papillomavirus (HPV), affecting both skin and mucosal surfaces.
- Anogenital warts involve infection of anal and genital mucosa and surrounding areas.
- Over 50% of sexually active adults are infected with one or more HPV types.
HPV Characteristics
- HPV is a naked double-stranded DNA virus, belonging to the Papovaviridae family.
- There are over 100 genotypes of HPV; 45 can affect the genital epithelium.
- The virus has 72 pentameric capsomeres, with major and minor capsid proteins arranged on a skewed icosahedral lattice.
Genetic Structure
- HPV genes are categorized into early (E1-E7) and late (L1, L2) regions.
- Early genes regulate viral DNA replication and transcription.
- Late region genes encode major (L1) and minor (L2) capsid proteins and play roles in oncogenic transformation, particularly E6 and E7.
Infection Mechanism
- HPV is epitheliotropic, requiring differentiating squamous epithelium for replication.
- Viral DNA is present in lower epithelial layers, while capsid proteins and infectious virus are found in superficial layers.
- HPV cannot be cultured in vitro.
Risk Classification
- Low-risk HPV types (6 and 11) cause 90% of external anogenital warts and low-grade cervical cell changes.
- High-risk types (16 and 18) are linked to invasive cervical cancer, with HPV 16 having the greatest oncogenic potential.
Transmission
- Genital HPV is transmitted through sexual contact, often via microabrasions during intercourse.
- Digital transmission and perinatal transmission can occur, leading to laryngeal papillomatosis in infants.
Immune Response
- Both cell-mediated and humoral immunity play roles in HPV infection.
- Cross-reactivity is observed in immune responses, with cutaneous warts able to autoinoculate anogenital areas.
- Antibodies against HPV are present in the serum of individuals with warts; however, they do not eliminate lesions or prevent recurrences.
Antibody Response
- High rates of IgM, IgG, and IgA antibodies are found in patients with regressing warts.
- The presence of complement-fixing antibodies (IgG) correlates with higher cure rates, whereas their absence leads to slower healing.
Cellular Immune Response
- Increased cell-mediated immunity (CMI) is effective at eliminating and preventing wart recurrence.
- A dermal infiltrate of mononuclear cells is noted around spontaneous regressions of warts.
- Primary infected cells often evade immune recognition due to local inhibitory effects.
HPV Pathogenesis
- Antigens of HPV reside in the granular layer of the epidermis, limiting exposure and resulting in delayed CMI.
- Infection at the basal cell layer stimulates epithelial cellular proliferation and can lead to dysplasia or invasive cancer.
- E6 protein degrades p53, while E7 targets retinoblastoma protein, which disrupts cell cycle regulation.
Clinical Presentation
- Lesions may remain asymptomatic or appear within 1-8 months, typically averaging around 3 months after infection.
- Common sites in men include the inner lining of the prepuce, glans, urinary meatus, and shaft.
- In women, lesions typically occur in the labia, perineum, and perianal area, with subclinical infections appearing in the vagina and cervix.
- The most common presentation includes verrucous papules.
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Description
This quiz focuses on genital warts caused by the HPV virus, discussing its prevalence, causative agents, and effects on skin and mucosa. Learn about the various genotypes of HPV and their impact on sexually active adults. Test your knowledge about this significant health issue.
