We encounter viruses in our everyday life, some being worse than others. In this lesson, you will learn about the function and structure of HPV, including how it is transmitted and symptoms to look for.
What Is HPV?
Human papillomavirus (HPV) is an infectious human virus of the skin. There has actually been over 170 different forms of the virus identified. Of those forms, almost a quarter are transmitted sexually.
The virus, as most papillomaviruses do, can cause papillomas, or skin lesions. Often times, these come in the form of warts. As an STD, we see HPV to be the cause of genital warts. Other times, HPV causes no symptoms at all, making it nearly impossible for infected individuals to know they have it.
Unfortunately, some more sinister forms of HPV do not cause warts, but instead cause cervical cancer in women. Men are not safe from cancer either, as some forms can cause penile cancers. In both sexes, anal and pharyngeal cancers can also form from exposure to HPV.
How is it Spread?
HPV is spread most often through skin-to-skin contact between an infected and non-infected person. Typical infection will include warts or papillomas on the infected area. Upon infection, many (but not all) patients will experience flu-like symptoms prior to or at the same time as having an outbreak of warts.
An infected person can also pass the virus to other parts of their body through skin-to-skin contact. For instance, touching the infected genitals and then touching their face or body can spread the virus.As mentioned above, the most typical route of transmission is skin to skin. However, there is the possibility of a mother passing it to a newborn. To complicate things, if the newborn receives the virus this way, they run the risk of getting respiratory papillomavirus, or HPV of the lungs. Studies have found that blood can transmit the virus as well, however, the extent of this is still under investigation as it is a fairly new finding.
Structure of the Virus
Human papillomavirus is a non-enveloped virus.
What this means is that the virus exists without an envelope surrounding it for protection. Researchers have found that these types of viruses are typically more virulent and can thrive even in harsh environments.HPV exists as genetic material (DNA) surrounded by a protein-infused capsid. The genetic material is the blueprint for the virus, and the capsid acts to surround and protect the genetic material. The capsid is the car that drives the genetic material around to different host cells.The capsid also helps to bind to the particular cells that the virus needs to infect. Since there is no envelope, the virus is only protected by the capsid, and this has all of the proteins and enzymes needed to help the virus copy itself in order to survive.
Function of the Virus
HPV will only function and replicate in the epithelial cells of the skin, which can be found in the outermost layer of skin in humans. Exposure occurs when the epithelial cells are rubbed or broken by abrasion, such as that which occurs during sexual intercourse. This allows a break in the layer of cells, which in turn opens the door for the virus to attack. Exposure can also occur in places like the anus or throat since there are epithelial cells that line those areas.
As mentioned earlier, only certain types of HPV cause cancer. Unfortunately, a person may be exposed to multiple forms of the virus in one exposure, thus becoming infected with the wart-causing and cancer-causing versions of HPV.
The way HPV causes cancer is rather complex and is still being studied, but it works in the following, simplified way. The cancer-causing HPV viruses infect the host cells and turn off specific proteins that suppress tumor growth. Once these proteins are turned off, tumors or cancerous lesions can begin to grow without anything to stop them.
Human papillomavirus (HPV) is a skin infection in humans that can pass via skin-to-skin contact with an infected individual. It is found in over 170 different forms, some of which can cause warts, others of which can cause different types of cancers. There are also forms that cause no symptoms at all.HPV is a non-enveloped virus, meaning it has no envelope to protect the entire virus. It simply consists of genetic material (DNA) covered by a capsid, or protein shell. The virus enters the body through a break in epithelial cells, usually caused by friction or abrasion.With cancer-causing forms of HPV, the virus turns off tumor-suppressing proteins, which can lead to cervical, penile, anal, and esophageal cancers.