Lecture 4a: Oncogenic Viruses

Question 1

______ of all cancers are associated with infectious agents

Answer 1

20%

Question 2

______ of viral cancers occur in the developing world

Answer 2

80%

Question 3

Viral cancers do not arise acutely after infection, but instead develop __________ later

Answer 3

15-40 years

Question 4

Oncogenic viruses or tumor viruses

Answer 4

Viruses that cause or give rise to cancer

Question 5

The 7 well-accepted human oncoviruses account for ______ of all human cancer cases.

Answer 5

12%

Question 6

What are the seven well accepted human oncoviruses

Answer 6

-Epstein-Barr Virus (EBV)
-Human papillomavirus
-Hepatitis B and C viruses (HBV and HCV)
-Human T-cell lymphotropic virus-1 (HTLV-1)
-Human herpesvirus-8 (HHV-8)
-Merkel Cell Polyomavirus (MCPyV)

Question 7

The World Health Organization estimates _________ people worlwide are chronically infected with hepatitis C, which causes nearly _________ deaths per year, mostly from cirrhosis and liver cancer.

Answer 7

-71 million people
-400,000 deaths

Question 8

The most common risk factor for liver cancer is chronic infection with ___________

Answer 8

Hepatitis B virus (HBV) or Hepatitis C virus (HCV)

Question 9

HPV vaccination can prevent over ______ of cancers caused by HPV, as well as anal, vaginal, cervical, and vulvar precancers

Answer 9

90%

Question 10

Three most common types of cancer’s in people with HIV

Answer 10

-Kaposi’s Sarcoma
-Non-Hodgkins lymphoma
-Cervical Cancer.

Question 11

Direct Carcinogenic Viruses

Answer 11

Possess viral oncogenes that directly contribute to neoplastic cellular transformation (Kaposi Sarcoma herpesvirus or HPV)

Question 12

Indirect Carcinogenic Viruses

Answer 12

Cause chronic inflammation which may lead to oncogenic transformation

Question 13

The role of Oncoviruses in Aggressiveness of Malignancies

Answer 13

Oncoviruses may modulate the aggressiveness of cancers due to increased genomic instability, induction of phenotypic changes in cancer cells, and retuning of tumoral microenvironment

Question 14

Direct mechanisms of viral carcinogenesis

Answer 14

After infection oncoviruses are persistently maintained as genetic elements which can cause viral genomes to form episomes or integrate into the host genomic DNA

Question 15

Rous Sarcoma Virus discovery

Answer 15

In 1911, Peyton Rous discovered the Rous Sarcoma virus from a chicken sarcoma which reproduced all aspect of the tumor on injection into closely related chickens.