Devita, Hellman, and Rosenberg's Cancer

LWBK1006-03 LWW-Govindan-Review November 24, 2011 11:19

Chapter 3•Etiology of Cancer Part 1 37

Question 3.20. Retroviruses are:

A. RNA viruses that have the capacity to synthesize double-stranded

DNA from single-stranded viral RNA genome

B. DNA viruses that have the capacity to synthesize double-stranded

RNA from single-stranded viral DNA genome

C. Dependent on host nucleotide synthesis enzymes to replicate the viral

genome

D. Viruses that cause oncogenic transformation in humans only through

a direct transforming effect

Question 3.21. Retroviruses participate in oncogenic transformation through the follow-

ing mechanisms, EXCEPT:

A. By causing insertional mutagenesis

B. By affecting the expression of cellular growth and differentiation

genes

C. Acutely transforming viruses that insert an oncogene in the infected

cells

D. By inducing an inflammatory response in the tissue

Question 3.22. Which of the following features does the human T-cell lymphotropic virus

type I (HTLV1) have in common with human immunodeficiency virus

(HIV)?

A. Both HIV and HTLV1 lead to induction of syncytia in cultured

T cells.

B. Both retroviruses have a tropism for CD4+T lymphocytes, and result

in marked cellular immunodeficiency.

C. Significant viremia is detected in individuals infected with either

HTLV-1 or HIV.

D. All of the above.

Question 3.23. Pathogenesis of adult T-cell leukemia (ATL) from HTLV1 infection is

related to:

A. Insertion of the viral genome at specific locations in the T-cell genome

B. Presence of host-derived oncogene in the viral genome

C. The viral protein Tax transactivating many cellular genes, particularly

interleukin (IL)-2 and IL-2 receptor

D. HTLV1 infection increasing susceptibility of T cells to other trans-

forming viruses

Question 3.24. HTLV2 is a retrovirus with the following characteristics, EXCEPT:

A. It is closely related to HTLV 1.

B. HTLV2 can also cause ATL-like HTLV1.

C. It is transmitted by the same routes as HTLV1, such as sexual inter-

course, contaminated blood, and breastfeeding.

D. Convincing data for an etiologic role for HTLV2 in human disease

are lacking.