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HPV 68 - genital human papillomavirus
Last reviewed: 23.04.2024
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Among the currently known strains of the genomic human papillomavirus (HPV), the genus of alpha-papillomavirus (Alphapapillomavirus) is the most studied. This genus includes viruses of high oncogenic risk. Some experts classify HPV 68 as one of them, although they consider it a rare type.
Structure HPV 68 type
The structure of HPV 68 is practically no different from other papillomaviruses. HPV type 68 forms an icosahedral capsid (protein shell) with a diameter of 50 nm. The capsid consists of 72 pentamers of the structural protein L1 linked to each other by disulfide bonds. This binding mediates conformational changes in the capsid of the virus, which ensures the initial attachment of the virion to the host cell and promotes infection. [1]
The HPV 68 double-stranded circular DNA has a region that codes for early proteins E1-E7, and an L region that codes for late structural proteins of the viral envelope (L1 and L2).
The life cycle of a virus consists of several stages. At the initial stage, the virus must attach to the cell and penetrate through its membrane inside - by endocytosis. The viral DNA is then released into the host cell nucleus, integrating into its genome. After that, the virion is assembled inside the nucleus of the affected cell - with the encapsulation of genomic DNA with the L2 protein.
In the replication of the viral genome, the leading role is played by the virus proteins E6 and E7, which are considered oncogenic. They not only use the replication mechanism of cellular DNA to insert their own DNA into cells, but also neutralize the cellular protein p53, a tumor suppressor. In addition, the E7 protein, interacting with the transmembrane protein TMEM173, which induces the production of type I interferon, suppresses innate immunity. [2]
In this way, HPV is protected from the host defense mechanisms at the extra- and intracellular levels. And with a high activity of the immune system, the virus can wait out unfavorable conditions for itself, being in a latent form.
Read also - Human papillomavirus: structure, life cycle, how it is transmitted, prevention
To the question of oncogenicity of HPV type 68
Many types of human papillomavirus of the genus Alphapapillomavirus have a high risk of developing oncology. The number of such types varies from 13 to 19, and only 11 of them have been proven to be oncogenic.This is HPV 16, 18, 31, 33, 35, 45, 39, 51, 52, 56, 58.
They primarily infect the mucous membrane of the anogenital region, oral cavity and oropharynx. The most common ones are: HPV 16, 18, 45, 31, 33, 35, 52 and 58.
The carcinogenicity of these types is different. It is very high in HPV 16 and slightly lower in HPV 18 , which cause about 72% of cases of oncological diseases associated with papillomatous infection.
In almost 18% of cases of cervical cancer, viruses of the A9 group (HPV 31, 33, 35, 52, 58) and A7 (HPV 45 and 59) are detected. And the share of HPV 68, HPV 66, HPV 26, HPV 53, HPV 70, HPV 73 and HPV 82 - as an etiological factor of oncogenesis and single HPV infections in invasive cervical cancer - together account for 0.9-1.7%... According to some studies, in 55.3% of cases, the genotypes of viruses of the A7 or A9 groups are detected as coinfections.
Without sufficient clinical and epidemiological data to prove the oncogenicity of HPV 68, the International Agency for Research on Cancer (IARC) WHO has classified this type of papillomavirus as probably carcinogenic.
According to the latest figures from the US National Cancer Institute (NCI), HPV is the leading cause of approximately 5% of all cancers worldwide.
Symptoms
Cervical neoplasia is considered to be the result of persistent human papillomavirus infection. At the same time, HPV 68 alone is less likely than others to be involved in a malignant tumor of the cervix uteri.
Experts believe that HPV 68 in women can cause cervical dysplasia , which is accompanied by symptoms such as discomfort, as well as itching, burning or pain in the genital and suprapubic region; uncharacteristic vaginal discharge.
Read more in publications:
The problems associated with the human papillomavirus also apply to men, since the main mode of transmission of the virus is sexual. And HPV type 68 in men can cause cancer of the penis, anal cancer, oropharyngeal and laryngeal cancer.
What symptoms can be, in detail in the publications:
Diagnostics
How is the diagnosis of the human papillomavirus carried out, in detail in the articles:
- Human papillomavirus infection: detection of human papillomavirus
- Human papillomavirus tests
- Diagnostics of the cervical dysplasia
For methods for quantifying high-risk total HPV, real-time PCR (Hybrid Capture II test) is used. This assay assists in the diagnosis of sexually transmitted HPV infection and provides high-quality molecular detection of 13 different types of high-risk HPV (16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59, 68 - without differentiating the individual type of the virus (that is, genotyping).Therefore, there is no such thing as the norm of HPV type 68, and the result of the analysis establishes the viral load - the number of copies of genomic DNA (Lg) per cell equivalent (log10 viral copies / 1 ng of cell If in the decoding of the analysis the indicator does not exceed 3 Lg, then the concentration of CHD is considered clinically insignificant. [3]
We do not yet have a PCR kit with a genotype-titer HPV HCR (R-V67-F-CE) to identify, differentiate and quantify 14 HPV types (16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59, 66 and 68). Here, each type of HPV is registered separately, which makes it possible to differentiate the genotype of the virus and determine its amount. [4]