The Facts: Human Papilloma Virus
HPV Infect Mucous Tissues in the Cervix Leading to Cervical Cancer.
Oct 19, 2008
HPV are DNA viruses that use DNA to code their genes. HPV are very small. They have only eight genes in their DNA. HPV uses the proteins made from the eight DNA genes to complete its life cycle. First, HPV infects the cells of a person and then replicates (make additional viruses) and releases new viruses. The new viruses can then infect a different person during sexual or other close person-to-person contact.
What types of cells do HPV infect?
There are two types of HPV. One type is harmless. This type infects skin and causes warts. The second type of HPV infects specific cells found in mucosal surfaces (mucosal HPV). Mucosal HPV is dangerous because it can cause persistent infections that can lead to cancer. The infections caused by mucosal HPV are generally symptom-free, although some mucosal HPV cause genital warts. Genital warts do not lead to cancer.
Mucosal Surfaces
Mucosal surfaces are wet sheets of cells inside the body in the nose, mouth, stomach, intestines, anus and genital areas. Mucosal surfaces protect the body but also must allow nutrients and water to move in and out of the body. Consequently, mucosal surfaces are not as protective and impermeable as is the outer skin of the body. Viruses, such as HPV, and other microorganisms take advantage of the weaknesses of mucosal surfaces during infection.
Transition Zones
The HPV that cause cancer appear to prefer a particular type of mucosal surface called a “transition zone”. In some parts of the body, two different types of mucosal surfaces meet. The meeting point is a transition zone. A transition zone is similar to a fault line in the earth’s crust – it is a point of weakness where damage (earthquake or infection) can occur. In the body, the mucosal surface has reduced anti-infection defenses at the transition zone.
HPV and the Cervical Transition Zone
Mucosal HPV infections cause most cervical carcinomas. There is a transition zone in the cervix where the cervical mucosal surface changes to the type of mucosal surface found in the vagina. The cervical transitional zone is comprised of layers of cells. New cells start at the bottom, move to the top of the layer and then die. The cervical transition zone appears to be especially vulnerable to persistent infection by the HPV types that cause carcinoma.
HPV enter the cervical transition zone through small tears in the mucosal surface. HPV move to the bottom of the mucosal surface and infect the new cells. The virus then completes its life cycle inside the cell as the cell slowly moves from the bottom layer to the top, outer layer of the transition zone. At the top of the layer, the infected cell dies and releases new HPV, which begin another life cycle of infection.
Increase your knowledge of HPV in order to protect yourself and your daughter from the consequences of HPV infection.
