Chapter 6

Question 1

There are 2 main categories of oncogenic viruses DNA and RNA. One of the first viruses to be recognized was the Rous ___ virus. This virus was noted to contain a mutated version of which normal gene? This virus caused the development of ____ (type of tumors) in what species? This virus is what type of virus (DNA or RNA)?

Answer 1

Rous sarcoma virus
v-src
Sarcomas
Chickens
RNA/retrovirus

Question 2

The process of recombination of cellular and viral retroviral genes in front of a cellular oncogene is called ____.

Answer 2

Transduction

Question 3

For the following viruses, say whether they are DNA or retroviruses (RNA).

1. Hepatitis B Virus.
   * Assoc with what tumor type?
   * What animal has also been shown to induce tumor formation by this virus
   * In this animal what gene is often affected?
2. Hepatits C Virus.
3. HTLV
4. HIV
   * What subcategory of virus does this belong to?
5. Adenovirus
6. Epstein Barr Virus
   * Associated w/ what cancer type?
7. FeLV
8. Papillomavirus (HPV)
   * Assoc with what cancer type?
   * How does it cause tumor formation?

Answer 3

1. Hepatitis B - DNA
   * Assoc w HCC
   * Woodchuck hepatitis virus
   * Myc affected in woodchuck!
2. Hepatitis C - same family as W. Nile
3. HTLV - retrovirus (Adult T cell leukemia)
4. HIV - RNA (lentivirus)
5. Adenovirus - DNA (used for vax bc very immunogenic but cn be used repeatedly dt IR)
6. Epstein Barr - Burkitt’s LSA - B cell LSA w/ translocation bt c-myc and IgG heavy chain or light chain. Results in deregulation of c-myc expression (overexpressed since near IgG locus)
7. FeLV - retrovirus
8. HPV - DNA
   * Cervical carcinoma
   * Targets p53 for degradation (via ubiquitin pathway) leading to decrease p53 functional in the cells leading to decreased tumor surveillance and t/f tumor production

Question 4

In Hodgkin’s LSA,
What is malignant cell type?
What other cells commonly seen in association w/ these (ie. what cell is classic hallmark and what other group of non-cancerous cells are often seen in association w/ this diagnosis)

Answer 4

Hodgkin’s is a malignant mononuclear B cell LSA.
Other malignant cells include the multi-nuclear Reed Sternberg cells. These two cell types are set amongst background of reactive non-malignant lymphs.

RSCs are generally non-B/non-T and have escaped apoptosis

Question 5

Retroviruses have 3 main genes. Describe their functions:

Answer 5

ENV - envelope protein - a glycoprotein w/in the envelope that surrounds the core of the virus

GAG - makes the nuclecapsid core which contains 2 IDENTICAL single strands of viral RNA that are linked together at the 5’ ends

POL - reverse transcriptase enzyme (polymerase)

Question 6

There are 2 main categories of retroviruses - acute and chronic.

Explain the difference bt these 2 groups and give 1 example of each

Answer 6

Acute transforming viruses - rapidly transforming viruses. Contain viral oncogenes. Are replication deficient and need a competent partner in order to replicate. No introns present so transformation can occur quickly.
Ex: Feline Sarcoma Virus - affects signaling

Chronic or slowly transforming retroviruses do not have oncogenes. They transform by inserting the viral genome into chromosomal DNA (INSERTIONAL MUTAGENESIS) - proviral integration into normal genome leads to activation of oncogene in the normal genome or inactivation of a TSG - not as random as previously thought…which is why can see same mutation in multiple individuals.
Ex: Avian Leukemia Virus - induces B cell LSA by transforming myc (FeLV, Mouse Mammary tumor virus)