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45 Cards in this Set

  • Front
  • Back
what does expression of a viral oncogene product do to a cell?
disrupts reguation of cellular growth control
how can oncogenic viruses be detected in tumors?
by preparing a cell free extract of a tumor and testing the particle's ability to cause tumors when injected into lab animals AND by immunological methods
which three laboratory tests can be run to detect viral nucleic acids?
PCR, Southern blot, or northern blot
do virally induced tumors retain part of the viral genome or not?
yes, frequently
what is the difference in shape between normal and cancer cells?
normal cells are flat in culture. Cancer cells are more round
what is unique about the levels of actin and fibronectin in cancer cells?
loss of actin and reduced surface fibronectin
do viruses grow better in cells that are actively synthesizing DNA or not actively synthesizing DNA?
active DNA synthesis
what is the normal result of DNA viruses encoding genes that push a host cell into the cell cycle by modifying host proteins or gene expression?
cell death, but sometimes the host cells can transform
what is the name for the virus in humans, rodents, and monkeys from the papovavirus family?
human -- papilloma virus, rodents -- polyoma virus, monkeys -- SV40
what is the relative size of papovaviruses? Do they have envelopes? What is their nucleocapsid symmetry?
small; no; icosahedral
does the papovavirus rely on host cell proteins for many functions?
yes -- it has a small genome and must use host cell machinery
how many of the papovavirus genes are not used?
none. All are indispensable
what are the two categories of genes of papovaviruses?
early and late genes
is the T antigen gene an early or late gene in papovaviruses? What is its role?
early; it binds to the origin of replication and recruits host DNA polymerases
when does late transcription of genes occur in papovavirus? Which genes are encoded late?
after cell replication; capsid proteins
how are viral particles released in papovaviral infections?
cell lysis
what is the name of the papovavirus protein which binds to and inactivates tumor suppressor genes Rb and p53 in cells?
T antigen
which diseases are associated with human papilloma virus?
plantar warts, genital warts, cervical cancer, head cancer, neck cancer
what percentage of the HPV strains are associated with anogenital lesions?
33%
what percentage of cervical carcinomas harbor HPV viral sequences integrated into cellular DNA?
80-90%
what is the most common manifestation of urogenital HPV infection? Are these caused by the oncogenic HPV?
condylomas; no
75% of all cervical carcinomas are caused by which two HPV strains?
HPV16 and HPV18
which two HPV oncogenes have been identified? Are they early or late genes?
E6 and E7; early
in which, warts or carcinoma, is the viral genome found to be incorporated into host genome?
carcinoma
does E6 bind to Rb or p53? E7?
p53; Rb
are women with HPV 16 or 18 guaranteed to get cervical cancer? Why or why not?
no; because other cofactors are inbolved (such as cigarette smoking)
what kind of HPV vaccine is now available?
subunit
what kinds of tumors are adenoviruses associated with?
none in humans
which two proteins are involved in transformation of adenovirus infected cells in hamsters and rats? Which is capable of partially transforming cells on its own?
E1A and E1B; E1A
what is the action of E1 protein in adenovirus infections?
binds to Rb, p300, CBP and to cellular transcription factors to stimulate transcription associated with S phase where DNA replication occurs
which two herpesviruses are known to cause cancer? What are the cancers each causes?
epstein barr and kaposi's sarcoma herpes virus (HHV8); Burkitt's lymphoma and Kaposi's sarcoma, respectively
what is the most common childhood tumor in Africa? Are boys or girls at a greater risk?
Burkitt's lymphoma; boys
which type of cells are infected in Burkitt's lymphoma? Where are the tumors normally present?
B cells; jaw or lower abdomen
what is the histological appearance of tumors in Burkitt's lymphoma?
starry
how long is the life expectancy of patients who are diagnosed with burkitt's lymphoma?
6 months
is integration of viral genes required for cell transformation in Burkitt's lymphoma?
no
what chromosomal translocation is present in Burkitt's lymphoma patients? What does this do?
8 and 14 or 8 and 22; puts a proto-oncogene under control of an Ig gene
in what instances do chromosomal translocations in EB infected cells grow into tumors?
in immunocompromised patients; normally T cells take care of tumors
why is malaria thought to be a cofactor in development of Burkitt's lymphoma?
because it inhibits cell-mediated immunity in children
other than Burkitt's lymphoma, what other type of cancer can EB virus cause? In what population is this most prevalent?
nasopharyngeal carcinoma; older males in southern China and Southeast Asia
what is the impact of EB on immunosuppressed graft recipients?
causes post-transplant lymphoproliferative disease
what is the most frequent neoplasm occurring in patients with AIDS? What percentage of AIDS patients develop this?
AIDS-associated Kaposi's sarcoma; 15-20%
what characterizes tumors in Kaposi's sarcoma?
multiple pigmented, highly vascularized nodules of the skin
expression of which protein is high in kaposi's sarcoma cells? Is this a viral or cellular protein?
vascular endothelial growth factor, an angiogenic factor; cellular
which viral genes in kaposi's sarcoma are thought to be oncogenes?
G protein receptor, cyclin homolog, and LANA antigen