Question 1

Which of the following describes the best treatment for papillomavirus induced cervical lesions?

Accepted Answer

Treatment of papillomavirus induced cervical lesions typically involves removal of the lesion using a laser, known as a loop electrosurgical excision procedure (LEEP), or a cold knife conization. Vaccination with the vaccine against HPV is important for prevention, but is not a treatment for existing lesions. Radical surgery (hysterectomy) is only required for severe cases or if there is evidence of cancer. Injection of antibodies against HPV into the lesion and systemic anticancer drugs are not effective treatments for cervical lesions caused by HPV.

Question 2

The E2 protein from papillomaviruses can bind to the viral DNA and to mitotic chromosomes.What purpose might this serve for the virus?

Accepted Answer

The ability of the E2 protein to bind to mitotic chromosomes allows the viral DNA to be properly segregated to each daughter cell during cell division, increasing the chances of the virus being transmitted to future generations of cells.

Question 3

Which of the following describes the mechanism used by the E6 protein of papillomaviruses to remove the p53 protein.

Accepted Answer

The E6 protein of papillomaviruses promotes the ubiquitination of the p53 protein, leading to its degradation by the proteasome.

Question 4

Cervical tumors caused by human papillomavirus do not show the typical mutations in the p53 gene that most cancer cells have.Which of the following explains why?

Accepted Answer

The E6 protein produced by human papillomavirus binds to and degrades the p53 protein, preventing it from functioning properly. This is a common mechanism by which HPV-induced cervical tumors avoid the typical p53 mutations seen in other cancers.

Question 5

The cultured human cell line HeLa expresses the E6 and E7 proteins of human papillomavirus.What would happen to these cells if the expression of these proteins was shut off?

Accepted Answer

The E6 and E7 proteins of human papillomavirus (HPV) are known to inhibit tumor suppressor proteins p53 and Rb, respectively. Shutting off their expression would remove this inhibition, allowing these tumor suppressor pathways to become active again, leading to apoptosis.

Question 6

Which of the following proteins from papillomavirus can bind to the viral origin of DNA replication and unwind the DNA strands?

Accepted Answer

E1 is the papillomavirus protein that binds to the viral origin of DNA replication and unwinds the DNA strands, allowing for the initiation of viral DNA replication. E2 is also involved in viral replication but does not directly unwind the DNA strands. E6 and E7 are oncoproteins that promote cellular proliferation and disruption of cell cycle control, and L1 is the major capsid protein of the viral particle.

Question 7

The E7 proteins from the oncogenic strains of papillomaviruses bind to pRb more tightly than the E7 proteins from nononcogenic strains of the virus.

Accepted Answer

This statement is true. The E7 proteins from oncogenic strains of papillomaviruses have amino acid sequences that are better suited for binding to the tumor suppressor protein pRb, compared to the E7 proteins from nononcogenic strains. This allows the oncogenic strains to more effectively disrupt the regulation of the cell cycle and contribute to the development of cancer.

Question 8

The E6 proteins from highly oncogenic papillomaviruses have been shown to interact with cellular proteins, which control cell polarity and proliferation, that contain which of the following protein domains?

Accepted Answer

The E6 proteins from highly oncogenic papillomaviruses have been shown to interact with cellular proteins that contain the PDZ domain, which controls cell polarity and proliferation.

Question 9

In papillomaviruses, plasmid replication produces a large number of viral genomes which will be packaged into new virions.

Accepted Answer

Papillomaviruses do not use plasmid replication to produce new virions. Instead, they use the host cell's DNA replication machinery to make multiple copies of their genome, which are then assembled and packaged into new virions.

Question 10

Which of the following describes the form that the papillomavirus genome is found in most cervical cancer cells?

Accepted Answer

In most cervical cancer cells, a fragment of the papillomavirus genome, particularly the E6 and E7 oncogenes, is integrated into the host cell's genome, which disrupts normal cell regulation and contributes to cancer development.

Question 11

The human papillomavirus can produce condylomas.What is the more common term to describe this type of skin lesion?

Accepted Answer

The more common term to describe this type of skin lesion produced by the human papillomavirus is genital wart.

Question 12

The currently available HPV vaccines contain virus-like particles composed of which of the following?

Accepted Answer

The currently available HPV vaccines contain virus-like particles composed of the L1 protein alone. These virus-like particles are non-infectious because they lack the viral DNA, but they can still stimulate the immune system to produce antibodies against HPV.

Question 13

Which of the following cellular events causes the papillomavirus to enter "vegetative replication"?

Accepted Answer

Papillomavirus enters vegetative replication when the infected keratinocytes undergo terminal differentiation. This process allows the virus to replicate its DNA and produce viral proteins necessary for assembling new virus particles in the upper layers of the epithelium.

Question 14

The E7 protein from papillomavirus stabilizes the cellular p53 protein, which leads to cell cycle arrest.Which of the following explains the mechanism by which p53 causes cell cycle arrest?

Accepted Answer

p53 activates transcription of p21, which in turn inhibits cyclin-dependent kinase activity, leading to cell cycle arrest. This occurs by blocking phosphorylation of pRb, which is necessary for progression through the cell cycle. Choices B and C are incorrect, as p53 does not directly bind to pRb or p21 to cause their release or degradation, respectively. Choice D is also incorrect, as p53 binds to the viral E6 protein, not the other way around.

Question 15

Which of the following is thought to be the reservoir for human papilomaviruses?

Accepted Answer

Human papillomaviruses (HPVs) are primarily associated with the human genital tract, affecting both males and females. They are known to infect the skin and mucous membranes of the genitals, making both male and female genital tracts reservoirs for these viruses.

Question 16

Papillomaviruses replicate in differentiated keratinocytes, which are not actively dividing.How does the virus handle this situation?

Accepted Answer

The answer of Papillomaviruses replicate in differentiated keratinocytes, which are...

Question 17

When the late promoter of papillomaviruses is activated, it increases production of the E1 and E2 proteins.Which of the following explains why an increase in these two proteins would contribute to vegetative replication of the virus?

Accepted Answer

The E1 and E2 proteins of papillomaviruses are involved in initiating DNA replication of the viral genome. Therefore, an increase in these proteins would contribute to vegetative replication of the virus.

Question 18

Productive infections with human papillomaviruses have been difficult to study in cultured cells.Which of the following explains why?

Accepted Answer

Productive infections with human papillomaviruses only occur in differentiated keratinocytes, which are difficult to maintain in culture. Therefore, it is difficult to study productive infections with these viruses in cultured cells.

Question 19

Mutations in the p53 gene are seen in over 50% of human tumors.

Accepted Answer

Mutations in the p53 gene are commonly observed in cancer, with a frequency of approximately 50% or higher.

Question 20

The papillomaviruses used to be classified in the same family as the polyomaviruses.Which of the following is a feature that distinguishes them from polyomaviruses?

Accepted Answer

Papillomaviruses transcribe their genome from only one strand, unlike polyomaviruses.

Quiz 22: Papillomaviruses