HPV (Human papillomavirus) is a family of over 200 related viruses (the Papillomaviridae family) that can infect the skin and mucous membranes. A significant portion of the global population is exposed to HPV at some point in their lives [1].
HPV types can be classified by their potential to induce cancer (high risk vs low-risk types). Types of HPV with low oncogenic risk are associated with warts (genital warts) and in most cases are associated with transient infections [2]. High-risk types of HPV are also associated with infections, usually transient, but with a higher likelihood of persistence. Along with other risk factors, high-risk types of HPV can integrate into the DNA of the host cells, which over time can transform into malignancies.
The viruses are highly tissue-specific and infect the basal cells of the skin and mucous membranes. HPV enters the host cell through micro-abrasions or lesions in the skin or mucous membranes.
Once inside the host cell, the viral genome is transported to the nucleus. Viral DNA replicates and transcription of viral genes occurs, leading to the synthesis of early and late proteins. The viral genome is organized into three regions: early (E), late (L), and long control region (LCR) [3]. The early region encodes proteins involved in viral replication, transcriptional regulation, and modulation of host cell functions, while the late proteins enter the structure of the viral capsid. On the basis of the genomic sequence of L1, the gene encoding the principal capsid protein, over 200 HPV types have been identified and characterized, of which at least 12 are associated with cancers [4].
HPV subtype 16 is associated with about 55-60% of cervical cancers, and HPV subtype 18 is involved in a percentage of 10-15% of cases. Another eight subtypes (31, 33, 35, 45, 51, 52, 56 and 58) are associated with most other cases of cervical cancer. HPV infection subtypes 16 and 18 may increase the risk of developing cervical intraepithelial neoplasia by 11 to 17 times [5].
Understanding the molecular and cellular biology of HPV is critical for developing targeted therapies, vaccines, and diagnostic tools to prevent and manage HPV-related diseases, including cancers and warts.
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