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Viruses can cause cancer in animals and humans. A principle of viral carcinogenesis is that
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(A) Retroviruses cause most types of human cancer.
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(B) Not all infections with a human cancer virus lead to tumor formation.
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(C) Short latent periods elapse between time of virus infection and tumor appearance.
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(D) Animal models seldom predict cellular mechanisms in human cancer.
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(E) Host factors are insignificant in influencing the development of virus-induced human cancer.
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Cellular oncogenes represent activated genes involved in cancer. A second class of cancer genes is involved in cancer development only when both alleles of such a gene are inactivated. The second class of genes is called
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(C) Tumor suppressor genes
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A 38-year-old woman is diagnosed with cervical cancer. This cancer is common worldwide and has a sexually transmitted viral etiology. The causative agent of human cervical cancer is
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(C) Human papillomaviruses, high-risk types
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Retroviruses encode an enzyme called reverse transcriptase. The function of the reverse transcriptase enzyme is
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(B) RNA-dependent DNA polymerase activity
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(C) DNA-dependent RNA polymerase activity
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(D) RNA-dependent RNA polymerase activity
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(E) Topoisomerase activity
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Two months after a kidney transplant, a 47-year-old man developed nephropathy. Up to 5% of renal allograft recipients develop nephropathy. A viral cause of some of the nephropathy cases has been identified as
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(B) Human papillomavirus, all types
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(C) Human papillomavirus, low-risk types
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(E) Human cytomegalovirus
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Human papillomavirus can cause cancer in humans and is most commonly associated with
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A virus that causes human cancer is also associated with a nervous system disorder called tropical spastic paraparesis. That virus is
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(D) Human T-lymphotropic virus
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(E) Human immunodeficiency virus
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The polyomaviruses encode oncoproteins called T antigens. These viral gene products
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(A) Are not needed for virus replication
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(B) Interact with cellular tumor suppressor proteins
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(C) Function to integrate the viral provirus into the cellular chromosome
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(D) Mutate rapidly to allow the virus to escape immune clearance by the host
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(E) Are not able to transform cells in culture
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Cancer viruses are classified in several virus families. Which of the following virus families contains a human cancer virus with an RNA genome?
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Laryngeal papillomas in children are generally caused by the same viruses that cause benign genital condylomas. These viruses are
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(A) Papillomaviruses, types 6 and 11
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(D) Molluscum contagiosum virus
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(E) Papillomaviruses, types 16 and 18
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Vaccines against the most common HPV types that cause genital infections were approved in 2006 and 2007. They are aimed for use in which of the following population(s)?
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(A) All adults, both men and women
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(C) Women with precancerous cervical lesions
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(D) All adolescents and young adults, both boys and girls
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(E) Adolescent and young adult females
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Which of the following best describes available HPV vaccines?
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(A) Live attenuated virus
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(B) Live recombinant virus
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(C) Noninfectious subunit
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Many of the oncogenic retroviruses carry oncogenes closely related to normal cellular genes, called proto-oncogenes. Which one of the following statements concerning proto-oncogenes is incorrect?
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(A) Several proto-oncogenes have been found in mutant form in human cancers that lack evidence for viral etiology.
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(B) Several viral oncogenes and their progenitor proto-oncogenes encode protein kinases specific for tyrosine.
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(C) Some proto-oncogenes encode cellular growth factors and receptors for growth factors.
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(D) Proto-oncogenes are closely related to transposons found in bacteria.