Viruses can cause cancer in animals and humans. A principle of viral carcinogenesis is that
(A) Retroviruses cause most types of human cancer.
(B) Not all infections with a human cancer virus lead to tumor formation.
(C) Short latent periods elapse between time of virus infection and tumor appearance.
(D) Animal models seldom predict cellular mechanisms in human cancer.
(E) Host factors are insignificant in influencing the development of virus-induced human cancer.
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
(C) Tumor suppressor genes
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
(C) Human papillomaviruses, high-risk types
Retroviruses encode an enzyme called reverse transcriptase. The function of the reverse transcriptase enzyme is
(B) RNA-dependent DNA polymerase activity
(C) DNA-dependent RNA polymerase activity
(D) RNA-dependent RNA polymerase activity
(E) Topoisomerase activity
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
(B) Human papillomavirus, all types
(C) Human papillomavirus, low-risk types
(E) Human cytomegalovirus
Human papillomavirus can cause cancer in humans and is most commonly associated with
A virus that causes human cancer is also associated with a nervous system disorder called tropical spastic paraparesis. That virus is
(D) Human T-lymphotropic virus
(E) Human immunodeficiency virus
The polyomaviruses encode oncoproteins called T antigens. These viral gene products
(A) Are not needed for virus replication
(B) Interact with cellular tumor suppressor proteins
(C) Function to integrate the viral provirus into the cellular chromosome
(D) Mutate rapidly to allow the virus to escape immune clearance by the host
(E) Are not able to transform cells in culture
Cancer viruses are classified in several virus families. Which of the following virus families contains a human cancer virus with an RNA genome?
Laryngeal papillomas in children are generally caused by the same viruses that cause benign genital condylomas. These viruses are
(A) Papillomaviruses, types 6 and 11
(D) Molluscum contagiosum virus
(E) Papillomaviruses, types 16 and 18
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)?
(A) All adults, both men and women
(C) Women with precancerous cervical lesions
(D) All adolescents and young adults, both boys and girls
(E) Adolescent and young adult females
Which of the following best describes available HPV vaccines?
(A) Live attenuated virus
(B) Live recombinant virus
(C) Noninfectious subunit
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?
(A) Several proto-oncogenes have been found in mutant form in human cancers that lack evidence for viral etiology.
(B) Several viral oncogenes and their progenitor proto-oncogenes encode protein kinases specific for tyrosine.
(C) Some proto-oncogenes encode cellular growth factors and receptors for growth factors.
(D) Proto-oncogenes are closely related to transposons found in bacteria.