Papillomaviridae

The family Papillomaviridae contains only the human pathogenic genus Papillomavirus, which includes the human papillomavirus with numerous serotypes. The members of this family are epitheliotropic, naked double-stranded DNA viruses with a size of 55 nm, which infect the squamous epithelia of skin and skin-related mucous membranes. Target cells are the basal cells of the epithelia. However, the receptors on the basal cells are not yet known (integrins, heparan sulfate-substituted proteoglycans?).

Currently, > 170 different HPV subtypes are known. Some cause benign epithelial tumors in humans and animals (e.g. verrucae planae juveniles, verrucae vulgares, verrucae plantares, condylomata acuminata). Others are associated with genital or extragenital carcinomas (cervical carcinoma, periungual carcinomas). HPV are assigned to 5 supergroups (A-E) based on their sequence relatedness. HPV that infect the mucosa form group A, while HPV that infect the skin belong to groups B and E. A distinction is made between manifest, subclinical and latent infection (virus persistence in basal keratinocytes).

The circular genome of the Papillomaviridae comprises 7,500-8,000 base pairs. The genome is packaged in an icosahedral capsid. The capsid is composed of two structural proteins, L1 and L2, with L1 being the major capsid. All protein-coding sequences are located on one DNA strand.

The site of origin of the replication of the viral genome in the infected host cell is the 400-1,000 base pair LCR region (LCR = long control region). Downstream follow the translation reading frames E1-E7 (E = early), which encode proteins required for viral DNA replication, transcription and cell transformation. This is followed by 2 reading frames required for structural proteins L1 and L2 (L = late). The viral genomes are transcribed into numerous, distinct mRNA molecules starting from multiple promoters. The promoter activity is controlled by several viral and cellular factors.

1. Buntin DM, Rosen T et al (1999) Sexually transmitted diseases: viruses and ectoparasites. J Am Acad Deratol 255 527-534
2. Bzhalava D et al. (2015) International standardization and classification of human papillomavirus types. Virology 476:341-344.
3. Hilfrich R (2018) Skin cancer screening PLUS-The early detection of HPV-related squamous cell carcinoma in dermatologic practice. Act Dermatol 44: 140-143
4. Ockenfels HM (2016) Therapeutic management of cutaneous and genital warts. J Dtsch Dermatol Ges 14:892-899.
5. Rübben A (2011) Clinical algorithm for the therapy of cutaneous extragenital HPV-induced warts. Dermatologist 62: 6-16