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