Deck 25: Baculoviruses

Question 1

Which of the following assays was used to identify the baculovirus late expression factors?

A)A Southern blot
B)A reporter assay using the luciferase gene.
C)A reporter assay using the chloramphenicol acetyl transferase gene
D)A DNA replication assay using the restriction enzyme DpnI.
E)An in vitro transcription assay.

Answer 1

C

Question 2

Baculoviruses can infect and replicate in human but do not cause any disease.

Answer 2

False

Question 3

Which of the following describes the size and structure of the dsDNA genome of AcMNPV,a member of the baculovirus family?

A)Covalently closed circle of about 50kbp.
B)Covalently closed circle of about 150kbp.
C)Linear molecule of about 50kbp.
D)Linear molecule of about 150kbp.
E)Three linear segments of about 50kbp each.

Answer 3

B

Question 4

The late and very late genes of baculoviruses contain promoters that have sequences that are distinct from those of the host cell promoters.Which of the following explains why?

A)These unique sequences bind the cellular RNA polymerase more tightly.
B)The virus uses virus specific transcription factors to regulate viral transcription.
C)These sequences are recognized by the viral DNA polymerase.
D)These sequences are recognized by the viral RNA polymerase.
E)These sequences form a unique secondary structure that influences transcription.

Question 5

Assays that were used to study baculovirus DNA replication had to distinguish the plasmid DNA that was originally transfected into the cells from the DNA that was replicated in the eukaryotic cells.Which of the following describes how this was accomplished?

A)Digestion of DNA with a methylation dependent restriction enzyme.
B)Using a southern blot to distinguish the different types of DNA.
C)Using electron microscopy to distinguish the different types of DNA.
D)Using standard agarose gel electrophoresis to measure different sizes of DNA.
E)Measuring the sizes of the large DNA with a pulsed-field gel electrophoresis.

Question 6

The occlusion bodies of baculovirus consist of a single protein.Which of the following is this protein?

A)polyhedrin
B)occludin
C)tegument
D)GP64
E)baculin

Question 7

Which of the following groups of organisms is the primary host for baculoviruses?

A)mammals
B)insects
C)plants
D)bacteria
E)worms

Question 8

All of the following describe differences between the budded and occluded virions of baculovirus EXCEPT:

A)Occluded virions can survive in the environment better than budded virions.
B)Occluded virions usually contain more than one viral genome.
C)Occluded virions can infect a wider variety of insect species than budded virions.
D)The tegument of occluded virions contains the GP41 tegument protein.
E)Occluded virions are much less infectious in cultured cells.

Question 9

The budded virions produced during a baculovirus infection are primarily involved in which of the following?

A)Shutting down host defense mechanisms.
B)Surviving the harsh conditions of the environment.
C)Transmission via eggs laid by an infected female.
D)Transmission between different hosts.
E)Transmission of the virus between cells within a host.

Question 10

A great deal of research has gone into making baculoviruses more pathogenic and deadly to their hosts.Which of the following explains why?

A)They are investigated as germ warfare agents.
B)They could be used to destroy weeds and other undesirable plants.
C)They could be used as pesticides to kill insects.
D)They kill bacteria and could be used as antibiotics.
E)They could be used to kill cancer cells.

Question 11

Which of the following observations was the MOST crucial in the development of recombinant baculoviruses that can express large amounts of foreign proteins?

A)Baculoviruses can enter mammalian cells but can not replicate.
B)The polyhedrin gene is not essential for virus replication in cell culture.
C)Viruses missing the polyhedrin gene can be distinguished from wild-type viruses microscopically.
D)Recombinant viruses can produce large amounts of a foreign protein when introduced into insect cells in culture.
E)The polyhedrin gene has a very strong promoter that produces large amounts of mRNA late in the infection.

Question 12

Which of the following is an unusual feature of baculovirus infections?

A)They produce two distinct types of virions.
B)The virion has two separate envelopes.
C)The virion contains a tegument layer.
D)They package more than one copy of the genome into a nucleocapsid.
E)They replicate their DNA genome in the cytoplasm.

Question 13

All of the following distinguish the baculovirus RNA polymerase from the eukaryotic RNA polymerase II EXCEPT:

A)The baculovirus RNA polymerase is only composed of 4 protein subunits.
B)The baculovirus RNA polymerase is associated with a capping enzyme.
C)The baculovirus RNA polymerase only recognizes viral promoters.
D)The baculovirus RNA polymerase transcribes viral DNA in the cytoplasm.
E)The baculovirus RNA polymerase is required for viral gene expression.

Question 14

How do the hosts of baculoviruses typically become infected with the virus?

A)They are injected with virus by a parasitic wasp
B)They hatch from an infected egg.
C)They breathe in aerosoled virus particles.
D)They feed on virus contaminated plants.
E)They mate with an infected host.

Question 15

Treatment of cells infected with baculovirus with $\alpha$ -amanitin toxin will inhibit immediate-early or early but not late viral gene expression.

Question 16

Treatment of baculovirus infected cells with the toxin $\alpha$ -amanitin,which inhibits RNA polymerase II,does not reduce levels of the viral late transcripts.Which of the following explains why?

A)Baculoviruses use the cellular RNA polymerase III to transcribe their late genes.
B)Baculoviruses produce their own RNA-dependent RNA polymerase.
C)Baculoviruses produce their own DNA-dependent RNA polymerase.
D)Baculoviruses produce such high levels of the late mRNAs that the inhibition does not matter.
E) Insect cells do not use RNA polymerase II to transcribe their genes.

Question 17

Which of the following proteins from baculovirus is responsible for transactivating the viral early genes and is the major regulator of viral gene expression?

A)IE-0
B)IE-1
C)IE-2
D)PE38
E)LEF-1

Question 18

What is the function of the products of the very late genes in baculoviruses?

A)Replication of viral DNA.
B)Death of the host organism.
C)Assembly of budded virions.
D)Assembly of occluded virions.
E)Lysis of the host cell.

Question 19

The homologous repeat sequencs (hrs)found in the genome of baculoviruses are involved in which of the following viral events?

A)Processing of mRNAs
B)Translation of mRNAs
C)Enhancement of transcription.
D)Initiation of DNA replication.
E)Both transcription and replication.

Question 20

The tubular nucleocapsids of baculovirus allows the virion to accept a longer genome than normal.

Question 21

Describe some of the characteristics of baculoviruses that make them able to be used as safe pesticides to kill insects that are agricultural pests.

Question 22

During evolution of baculoviruses they appear to have acquired several genes from the genomes of their cellular hosts via recombination.

Question 23

You want to express large amounts of a foreign protein in insect cells.Describe how you would prepare a recombinant baculovirus that would be able to do this.Assume that you have the DNA encoding the foreign gene.

Question 24

Polyhedrin proteins from different baculoviruses have unique and different amino acid sequences.

Question 25

The budded or occluded virions of baculoviruses are identical in makeup except for the number of genomes they contains.