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Microbiology · Other DNA viruses

Human papillomavirus !

  • Virus
  • Non-enveloped (naked)
  • Exam priority: high

A very common sexually spread virus; some types cause warts and others, when they persist, cause cervical cancer.

Updated 2026-11-01

Also called: HPV, papillomavirus

At a glance

Shape
Icosahedral, non-enveloped
Genome
Circular double-stranded DNA
Envelope
Non-enveloped (naked)
Family
Papillomaviridae
Size
About 55 nm

Morphology

  • Naked icosahedral capsid, very hardy in the environment
  • Infects the basal squamous epithelium of skin and mucosa
  • Typical cytopathic effect: koilocytes (cells with a clear perinuclear halo and wrinkled nucleus)

Transmission

  • Sexual contact (vaginal, anal or oral), even without visible warts
  • Skin-to-skin contact for common warts
  • From birth canal to newborn: the origin of juvenile recurrent respiratory papillomatosis

Reservoir: Humans

Isolation precautions

What the care team adds to standard precautions.

  • Standard

Virulence factors

  • The E6 oncoprotein drives degradation of p53
  • The E7 oncoprotein inactivates the retinoblastoma protein (Rb) and releases the cell cycle
  • In high-grade lesions the viral DNA is often integrated into the host genome
  • Most infections clear on their own; cancer risk lies in persistent high-risk types

Diseases it causes

Clinical picture

  • Types 6 and 11 (low risk): genital warts and laryngeal papillomas
  • Types 16 and 18 (high risk): cause most cervical cancers; type 16 is the most oncogenic
  • Persistent infection is usually silent until a precancer or cancer appears

Diagnosis

  • High-risk HPV DNA test for screening
  • Cervical cytology (Pap smear): koilocytes and intraepithelial lesions
  • Colposcopy with biopsy to confirm
  • Warts are diagnosed by how they look

Treatment

There is no specific antiviral. Warts are treated by local destruction (cryotherapy, excision, laser) or topical immune modifiers such as imiquimod; cervical precancers are excised or ablated.

Drug class only; doses and regimens are set by the clinician from the current guideline.

Prevention

  • Vaccination before sexual debut
  • Cervical screening: cytology and HPV DNA testing by age
  • Condoms lower, but do not remove, the risk

Vaccine: Virus-like particle vaccine. Colombia's PAI uses the quadrivalent vaccine (6, 11, 16 and 18). The schedule (how many shots and for which groups, boys included) has been updated in recent years following WHO advice; the reference is the Ministry of Health's current PAI guideline.

Test yourself

Think of the answer, then tap the question to see it.

Which HPV oncoproteins inactivate p53 and Rb?

E6 drives degradation of p53 and E7 inactivates the retinoblastoma protein (Rb).

Which HPV types cause most genital warts?

Types 6 and 11, which are low risk for cancer and also cause laryngeal papillomatosis.

Which cell is characteristic of HPV infection on cytology?

The koilocyte: a squamous cell with a clear halo around an enlarged, irregular nucleus.

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← Back to the group: Other DNA viruses

Educational content on microorganisms; not a treatment guide and no substitute for a health professional's advice. No doses are given.

Sources: Human papillomavirus and cancer (WHO, 2024); Clinical Overview of HPV (CDC, 2024); Cáncer de cuello uterino (Ministerio de Salud y Protección Social de Colombia, 2024); Genital warts (MedlinePlus (NLM), 2024).

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