Question 1 : Characteristics of a malignant state include: 1) Dysregulation of the cell cycle and 2) Inhibition of apoptosis. These mechanisms are also hallmarks of a many viral infections? Why are these characteristics also beneficial to many viruses? Explain how viral genes/proteins from a specific virus dysregulate the cell cycle.

Question 2 : The first “cancer vaccines” have recently been approved by the FDA to prevent cervical cancer caused by the Human Papilloma Virus (HPV). Why would a vaccine against HPV prevent cancer? What are some of the mechanisms and viral proteins involved in induction of cancer by HPV?

Question 3 : Are viruses responsible for all cancers? This is a simple yet, provocative question. Read the article by evolutionary biologist Paul Ewald. Ewald postulates that most cancers are likely caused by pathogens such as viruses. What are the arguments for and against this theory? If his theory is true, how might this revolutionize the treatment and prevention of cancer? Why do viruses with low rates of transmission establish persistent infections that are frequently associated with cancer?

Question 4 : Read the article by Moore & Chang entitled "Why Do Tumor Viruses Cause Cancer?" Compare and contrast how viruses can act as direct or indirect carcinogens.

Objectives 

• You should understand what cancer is and the properties that distinguish transformed cells and untransformed cells.

• You should understand the four major cellular barriers to tumor formation in humans and why circumnavigation of these barriers can be helpful to a virus (See minilecture).

• You should understand common mechanisms viruses employ to circumnavigate normal controls on cellular proliferation

• You should be able to explain the differences between oncogneic viruses, transducing viruses and non-transducing viruses.