HPV Virus: Structure and Function

Instructor: Jeremy Battista
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.

HPV under an electron microscope
HPV under electron micro

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.

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