Human Papillomaviruses

• What was noted by Chandler in 1845 regarding warts?

  He observed that a wart appeared after injuring his assistant beneath the thumbnail.
• What did Waelsch demonstrate in 1917 about warts?

  He demonstrated the induction of a lesion differing morphologically from the tumor of origin after inoculation.
• What did Ullmann note in 1923 regarding laryngeal papillomas?

  He noted the accidental transmission of laryngeal papillomas and used extracts on his own scarified arm.
• What significant association was demonstrated by zur Hausen in 1983?

  An association between cervical cancer and HPVs.
• What prestigious award did zur Hausen receive in 2008?

  Nobel Prize
• What type of viruses are human papillomaviruses (HPVs)?

  Small non-enveloped dsDNA viruses.
• How many different human papillomavirus (HPV) types are there?

  Over 200 different HPV types.
• What are the common manifestations of HPV infections?

  Warts (condyloma).
• What is the relationship between HPVs and cancer?

  HPVs can lead to cancer and are highly associated with cervical cancer.
• What challenges are associated with the diagnosis and management of HPV infections?

  Diagnosis and management can be challenging.
• In which cells can HPV live?

  HPV can only live in squamous epithelial cells.
• How are HPV types categorized?

  Based on whether they infect cutaneous (skin) cells or mucosal (anogenital) cells.
• What is the diameter of the HPV capsid?

  55 nm.
• What is the genomic organization of papillomaviruses?

  Circular genome (~7.9kb) associated with cellular histones contained within a viral capsid.
• What are the major proteins in the HPV capsid?

  L1 (major) and L2 (minor) capsid proteins.
• What is the role of the HPV genome as an episome?

  HPV completes its entire productive life cycle as a circular episome in differentiated squamous epithelium.
• What is the function of early genes E1 and E2 in HPV?

  E1 and E2 proteins play a role in regulating viral DNA transcription and replication.
• What is the role of E6 and E7 proteins in HPV?

  E6 and E7 proteins are involved in cell cycle deregulation and immune evasion.
• What is the function of the long control region (LCR) in the HPV genome?

  The LCR contains transcriptional and replication regulatory elements.
• How does the papillomavirus lifecycle begin?

  The virus enters through micro-abrasion/trauma in the epithelia.
• What receptors does the HPV virus bind to during infection?

  Heparan sulphate receptors on the basement membrane and secondary receptors like α-6 integrin.
• What is the role of E1 and E2 proteins during the early phase of the papillomavirus lifecycle?

  E1 and E2 proteins bind cooperatively to the viral origin of replication to initiate DNA replication.
• What occurs during the genome amplification phase of the papillomavirus lifecycle?

  Genome amplification occurs in differentiating cells of suprabasal layers, leading to a dramatic increase in viral genome copy number.
• How does the late phase of the papillomavirus lifecycle contribute to virus assembly?

  Expression of L1 and L2 capsid proteins allows self-assembly of viral capsids and packaging of viral genomes.
• What characterizes a persistent HPV infection?

  Not cleared by the immune system and characterized by persistently detectable type-specific HPV DNA.
• What is the formal definition of a latent HPV infection?

  Presence of HPV DNA in the absence of virion production.
• What is the estimated lifetime risk of genital warts in sexually active people?

  10%.
• What demographic factors influence the prevalence of genital warts?

  Age, sex, ethnicity, and sexual orientation.
• What is the peak age of prevalence for genital warts?

  20–24 years.
• What are some associated risk factors for genital warts?

  Younger age at onset of sexual activity, increasing number of lifetime sexual partners, and immunocompromise.
• How can HPV be transmitted?

  Transmission can occur from asymptomatic and sub-clinical patients.
• What is the immune response to HPV infection?

  The immune system influences the outcome of HPV infection, but not all infected hosts have a detectable immune response.
• What factors influence the clinical manifestations of HPV infections?

  The site of infection, the type of HPV infection, and the immune status of the infected individual.
• Where do common warts typically occur?

  On the back of hands and the knee.
• What types of HPV are most commonly associated with common warts?

  HPV 1, 2, 4, 27, and 57.
• Where do plantar warts typically occur?

  On the soles of the feet.
• What types of HPV are most commonly associated with plantar warts?

  HPV 1 and 4.
• What are flat warts characterized by?

  Slightly raised lesions with flat surfaces.
• What types of HPV are most commonly associated with flat warts?

  HPV 3 and 10.
• Where do filiform warts commonly grow?

  On the face and neck.