Deck 21: Polyomaviruses

Question 1

Studying the circular genomes of polyomaviruses allowed scientists to study the different properties of supercoiled DNA.

Answer 1

True

Question 2

Which of the following describes a function of the large T antigen from SV40?

A) Binds to early promoters and inhibits transcription of early mRNAs.
B) Induces new transcription factors that leads to late gene transcription.
C) Binds to the viral origin of replication and separates the DNA strands.
D) Binds to the cellular p53 protein, which prevents apoptosis.
E) All of the above are correct.

Answer 2

E

Question 3

Which of the following cellular proteins are packaged into the polyomavirus virions?

A) Tubulin monomers.
B) Actin monomers.
C) Histone octomers.
D) Myristylated proteins.
E) Transcription factors.

Answer 3

C

Question 4

The nuclear localization signal on which of the following proteins directs the SV40 genome into the nucleus of the infected cell?

A) Importin
B) VP1
C) VP2
D) Histone 2A
E) Large T antigen

Question 5

Binding of the large T antigen of SV40 to the cellular protein pRb causes which of the following to occur?

A) Degradation of the cellular protein p53
B) Activation of the apoptosis pathway.
C) Replication of viral DNA
D) Dissociation of the transcription factor E2F.
E) Blocks progression through the cell cycle.

Question 6

Under which of the following conditions do polyomaviruses cause tumors in their hosts?

A) Injection of high titers in young animals.
B) Injection of high titers in older animals.
C) Exposure to the virus via an aerosol.
D) Exposure to particularly tumorigenic strains of the virus.

Question 7

The simian virus 40 (SV40)was isolated from which of the following?

A) Mouse tissue extracts.
B) Monkeys used for HIV research.
C) Hepatitis virus B vaccine.
D) Cells used to produce poliovirus vaccine.
E) Human adenoidal tissue.

Question 8

Which of the following describes the structure of the polyomavirus capsid?

A) 72 capsomeres composed of hexamers of VP1
B) 72 capsomeres composed of pentamers of VP1
C) 60 capsomeres composed of hexamers of VP1
D) 60 capsomeres composed of pentamers of VP1
E) 12 capsomeres composed of pentamers of VP1 with the remaining capsomeres composed of hexamers of VP1

Question 9

The intergenic region on the SV40 chromosome contains DNA sequences that control which of the following processes?

A) Early gene transcription.
B) Late gene transcription.
C) DNA replication.
D) mRNA splicing.
E) All of the above EXCEPT "d" are correct.

Question 10

The SV40 middle T antigen can activate cell metabolism and the cell cycle by doing which of the following?

A) Binding to MAP kinase and activating it.
B) Interacting with the cellular c-Src protein.
C) Inactivating the PP2A phosphatase.
D) Interacting with the pRb protein.
E) Binding to and cleaving the p300 protein.

Question 11

Most individuals who were born in the US between 1941 and 1961 have been accidentally injected with SV40 contaminated poliovirus vaccine.

Question 12

If the histone proteins are removed from genome of SV40, which of the following will happen?

A) The DNA becomes supercoiled.
B) The DNA becomes nicked.
C) The DNA assumes a relaxed circle form.
D) The DNA becomes denatured.
E) Nothing happens to the DNA.

Question 13

The large T antigen from SV40 can bind to all of the following cellular proteins EXCEPT….

A) Poly(A) polymerase
B) DNA polymerase a
C) p53
D) pRb
E) p300

Question 14

The small T antigen of SV40 regulates the cell cycle of the host cell by DIRECTLY doing which of the following?

A) Turning on transcription of cyclin D1.
B) Turning on the activity of the MAP kinase.
C) Inhibiting the activity of the PP2A phosphatase.
D) Phosphorylating the transcription factor AP1.
E) Inactivating the p53 protein.

Question 15

SV40 induces the infected cell to enter the S phase of the cell cycle.What purpose does this serve for the virus?

A) The virus requires the breakdown of the nuclear envelope.
B) The virus requires the cellular splicing enzymes present during S phase.
C) The virus requires transcription factors made during S phase.
D) The virus requires the RNA polymerase II only present during S phase.
E) The virus requires the DNA replication enzymes made during S phase.

Question 16

Polyomaviruses are a major infectious cause of human cancers.

Question 17

Which of the following enzymes can permanently remove supercoiling from circular DNA molecule?

A) Histones
B) Restriction endonuclease
C) DNA ligase
D) Topoisomerase I
E) DNA gyrase

Question 18

Which of the following mechanisms is used by SV40 to produce several proteins from a single transcription unit?

A) Use of alternative start codons.
B) RNA editing.
C) Alternative mRNA splicing.
D) Ribosomal frameshifting.
E) All of the above.

Question 19

Which of the following must occur in nonpermissive cells which become transformed by the polyomavirus SV40?

A) The viral origin of replication must become inactivated.
B) Cellular DNA becomes packaged into virions.
C) The early viral genes become integrated into the host chromosome.
D) The Rb protein becomes bound to E2F.
E) The large T antigen proteins become degraded.

Question 20

The SV40 large T antigen contains all of the following functional protein domains EXCEPT:

A) Transactivation domain
B) DNA helicase domain
C) ATPase domain
D) Spliceosome binding domain
E) DNA binding domain

Question 21

The polyomavirus SV40 has been used as an in vitro model for studying the biochemistry of DNA replication in mammalian cells.Explain why SV40 is a good model for studying this process.

Question 22

The large T antigen of SV40 is a highly multifunctional protein.Describe three of the most important functions that this protein has in regulating the infection of a host cell with SV40.

Question 23

The enhancer sequence on the SV40 chromosome is located on the opposite side of the genome from the intergenic region.

Question 24

SV40 will only transform cells which are nonpermissive for productive viral infection.

Question 25

While SV40 can not cause tumors in monkeys or humans, it can transform rodent cells.Explain the molecular mechanisms that cause this to happen.

Question 26

If the smallest introns in the SV40 genome are lengthened, then the levels of the Large T-antigen increase.