Human Papilloma Viruses

Human Papilloma Viruses (HPV)

• Small, non-enveloped, icosahedral virus with circular double-stranded viral DNA
• Over 100 types with different tropisms and oncogenic potential
• Transmission occurs through skin-to-skin contact and small abrasions, with no viraemia
• Infections persist for 6-12 months and may resolve, but it's unclear if resolution includes integration into the host cell genome
• Continued detection may increase the risk of cancer development

Types of HPV Infections

• Skin-to-skin: types 1, 2, 3, and others, causing plantar warts and common warts
• Mucosal low-risk: types 6, 11, and others, primarily associated with genital warts
• Mucosal high-risk: types 16, 18, and others, associated with invasive cancer

Oncogenic Potential of HPV

• Integration of HPV into host genome leads to selective growth advantage and genomic instability
• E6 and E7 genes contribute to oncogenic potential
• Disruption or deletion of E2 transcriptional repressor increases cancer risk

Infection and Transmission

• Cumulative incidence of HPV infection: 38% within 2 years of first sexual intercourse
• Most people are unaware of their infection, with only 1% showing symptoms and 4% showing subclinical infection by cytology
• 10% show subclinical infection by DNA/RNA probe, and 50% test positive by PCR or antibody

Diagnosis and Testing

• Growing the virus is not practical, and DNA testing is available but not widely used in Nova Scotia
• PAP smear is used to detect changes produced by the virus
• HPV vaccine is available, covering high-risk types 16, 18, and low-risk types 6, 11, as well as 5 others (now 9-valent)

HPV Vaccine

• Efficacy is mediated by humoral immune response
• Can be given in 2 or 3 doses (0, 2, and 6 months)
• HPV or Pap testing is not required prior to administration
• Vaccine efficacy: 100% for HPV 16/18-related moderate/severe changes, 95% for HPV 6/11/16/18-related mild changes, and 99% for HPV 6/11/16/18-related genital warts

National Advisory Committee on Immunization Recommendations

• Females between 9-26 years old
• Males between 9-26 years old
• People at ongoing risk over 26, especially men who have sex with men (MSM)
• Not recommended for children under 9 years old

This quiz covers the characteristics, transmission, and oncogenic potential of Human Papilloma Viruses, including their structure, types, and infection process.