Introduction
Papillomaviruses (PV) are a diverse group of viruses that belong to the
Papillomaviridae family. They are small, non-enveloped viruses with a
circular double-stranded DNA genome. PV are known to infect a wide range
of vertebrate species, including humans.1-6 PV are
highly species-specific, meaning that different types of
papillomaviruses typically infect specific animal species. For instance,
human papillomaviruses (HPV) infect humans, bovine papillomaviruses
(BPV) infect cattle, and canine papillomaviruses (CPV) infect
dogs.2,7-11
HPV are the most extensively studied and clinically significant group of
PV in humans. They have more than 200 identified types, and each type is
designated with a number (e.g., HPV-16, HPV-18, etc.). HPV can be
categorized into low-risk types and high-risk types based on their
association with different diseases.10-13 Low-risk
HPV, such as HPV-6 and HPV-11, are associated with the development of
benign warts, known as papillomas. These warts commonly occur on the
skin and mucous membranes of the anogenital region, including the
genitals and anus. They can also appear on other parts of the body, such
as the hands and feet. Low-risk HPVs rarely lead to
cancer.3,12-17 High-risk HPV, including HPV-16,
HPV-18, HPV-31, HPV-33, HPV-45, and others, have the potential to cause
various types of cancer. The most significant cancer associated with
high-risk HPV is cervical cancer, which is the fourth most common cancer
in women worldwide. High-risk HPV can also cause other anogenital
cancers, such as anal, vaginal, vulvar, and penile cancers.
Additionally, they have been linked to a subset of head and neck
cancers, particularly oropharyngeal
cancer.3,11,13,16,17
Transmission of HPV occurs primarily through sexual contact, including
vaginal, anal, and oral sex. However, other routes of transmission, such
as vertical transmission from mother to child during childbirth or
non-sexual skin-to-skin contact, can also contribute to HPV
infection.6,8 HPV infects the basal cells of
epithelial tissues, where they establish a persistent infection. Most
HPV infections are transient and resolve spontaneously within a couple
of years without causing any symptoms or long-term health problems.
However, persistent infections with high-risk HPV can lead to abnormal
cellular changes, such as precancerous lesions, which may progress to
cancer over time.1,18-22
Prevention of HPV infections primarily focuses on HPV vaccination and
promoting safe sexual practices. HPV vaccines are highly effective in
preventing infection with the most common high-risk HPV types and have
the potential to reduce the incidence of HPV-related diseases, including
cervical cancer.23-27 Safe sex practices, including
condom use and limiting sexual partners, can help reduce the risk of HPV
transmission.16,23-25,27-30 Regular screening, such as
cervical cancer screening with Pap smears or HPV testing, is also
important for the early detection of abnormal cellular changes and
timely intervention.24-28
This study aimed to carry out a literature review considering several
aspects involving HPV infection: Global distribution, prevalence,
biology, host interactions, cancer development, prevention,
therapeutics, coinfection with other viruses, coinfection with bacteria,
association with head and neck squamous cell carcinomas (HNSCC), and
association with anal cancer.