KAROO NEWS - One-fifth. Nearly 20% of cancers worldwide are caused by a virus.
These viruses don’t cause cancer until long after they initially infect a person. Rather, the viruses teach the cells they take over how to escape the natural biological process of cell death.
This strategy sets these altered cells on a path for other genetic changes that can cause full-blown cancer years down the road.
As a microbiologist and researcher of viruses, I seek to understand how viruses affect living cells and the health of the people who are infected.
These particular viruses are unique and interesting, both for their effects on patients and because of the potential ways they might be treated or prevented.
Seven cancer-causing viruses
There are currently seven viruses known that can cause cancer, which are technically called "oncogenic viruses."
The viral landscape
All known viruses can be categorized into one of 22 distinct families. Five of these families are called “persisting,” because once a person is infected, the virus remains in their body for life.
One example is the herpes virus that causes chickenpox in children and can reappear later in life as shingles. This ability to survive over the long term helps the virus spread from person to person.
There are seven known viruses that can cause cancer. Five of them are members of persistent virus families. The human papillomavirus, commonly known as HPV and known to cause cervical cancer, is in the papilloma family. The Epstein-Barr virus, which causes Hodgkin lymphomas, and the Kaposi’s sarcoma-associated virus, are both in the herpes family.
The human T-lymphotropic virus, which can cause a type of leukemia, is what’s known as a retrovirus. And Merkel cell polyoma virus, which causes Merkel cell carcinoma, is in the polyoma family.
All five of these viruses contain genetic code for one or more proteins that teach cells how to avoid cell death, effectively immortalizing them and promoting cell growth.
The cancer cells that develop from these oncogenic viruses all contain their original viruses’ genetic information, even when they appear years after the initial infection.
But only a small percentage of people who are infected with one of these five oncogenic viruses ultimately develop the full-blown cancer associated with it.
