Deck 24: Herpesviruses

Question 1

Which of the following describes the function of the $\alpha$ -TIF/VP16 protein from herpes simplex virus?

A)It shuts off expression of cellular proteins.
B)It activates transcription of immediate-early genes.
C)It uncoats the viral DNA at the nuclear pore.
D)It represses transcription of immediate-early genes.
E)It is required for the transition between a and b gene expression.

Answer 1

It activates transcription of immediate-early genes.

Question 2

The EBNA1 protein is absolutely required for replication of the genome of Epstein-Barr virus during latent infection of B lymphocytes.Which of the following is NOT a function of the EBNA1 protein?

A)Binds to multiple sites on the oriP.
B)Serves as the primer for DNA replication.
C)Directs cellular replication enzymes to the viral genome.
D)Segregates the viral DNA into daughter cells.
E)Enhances expression of the latency genes.

Answer 2

B

Question 3

Both HSV and EBV,which are members of the herpesvirus family,have mechanisms that prevent the immune system from recognizing and killing infected cells.Which of the following explains why this is important?

A)Herpesviruses are maintained in the host for life in a latent infection.
B)Herpesviruses are very sensitive to the effects of the immune system.
C)Herpesviruses are rarely transmitted to new hosts.
D)Herpesviruses infect cells that are components of the immune system.

Answer 3

A

Question 4

A few of the latency-associated transcripts (LATs)from herpes simplex virus have an unusual structure.Which of the following describes how they are unusual?

A)They are covalently closed circular RNA.
B)They have a high degree of secondary structure.
C)They have two separate open reading frames.
D)They represent a stable intron lariats.
E)They form double-stranded RNA with the ICP0 mRNA.

Question 5

Which of the following describes the distinguishing features of the three types of latency exhibited by the Epstein-Barr virus?

A)Whether the viral DNA is integrated into the host chromosome or not.
B)The number of copies of the viral genome maintained.
C)The type of envelope glycoproteins on the cell surface.
D)The cell types that are latently infected.
E)The number and type of EBNA and LMP genes expressed.

Question 6

Herpes simplex virus (HSV)maintains a latent infection in neurons while Epstein-Barr virus (EBV)maintains latency in B lymphocytes.While EBV maintains a low level of viral DNA replication,HSV does not replicate its genome at all during latency.Which of the following explains this difference?

A)B lymphocytes degrade some of the EBV genomes.
B)Neurons are a non-dividing cell type while B cells still divide.
C)HSV integrates its genome into the host cell genome while EBV does not.
D)Neurons replicate much more quickly than B cells.
E)Neurons live for the life of the host and never die.

Question 7

In addition to encoding enzymes and proteins directly involved in replicating the viral genome,herpes simplex virus also encodes thymidine kinase and ribonucleotide reductase,which are absolutely required for infection of neurons.Which of the following explains what role these proteins play?

A)They phosphorylate cellular proteins,which force the neuron into S phase.
B)They increase the pool of nucleotide triphosphates required for DNA replication.
C)They phosphorylate the tegument proteins before they are packaged into the virion.
D)They cleave the concatemers of the viral DNA as they are being packaged into capsids.
E)They help assemble the DNA replication complex on the viral origin.

Question 8

Herpesviruses hardly ever cause serious or fatal infections,even in patients with reduced immune function.

Question 9

The $\alpha$ genes of herpes simplex are expressed at which time point during the viral replication cycle?

A)Immediate-early
B)Early
C)Delayed-early
D)Late
E)Delayed-early and late

Question 10

During one round of infection with the herpes simplex virus,all four isoforms of the viral genome are produced.

Question 11

Which of the following describes the major function of the proteins made from the $\alpha$ genes of herpes simplex virus?

A)Replication of the viral DNA.
B)Assembly of the capsid.
C)Regulation of viral gene expression.
D)Inhibition of the production of antibodies.
E)Formation of the tegument and envelope.

Question 12

Which of the following two herpesviruses have been associated with human cancers?

A)Herpes simplex 1 and 2
B)Herpes simplex 1 and varicella-zoster virus.
C)Epstein-Barr virus and cytomegalovirus.
D)Epstein-Barr virus and Kaposis' sarcoma virus
E)Human herpesvirus virus 6 and 7.

Question 13

Which of the following characteristics of the virion of herpesviruses is atypical of most enveloped viruses?

A)There is an amorphous protein layer between the capsid and envelope.
B)The capsid is composed of both a major and a minor protein.
C)The envelope contains multiple glycoproteins.
D)The capsid has icosahedral structure.
E)The DNA is packaged through a portal protein.

Question 14

Epstein-Barr virus particles released from infected B lymphocytes have reduced infectivity for B lymphocytes but enhanced infectivity for epithelial cells.Which of the following explains this phenomenon?

A)Epithelial cells have higher levels of the HVEM receptor protein.
B)B lymphocytes do not contain the correct host cell receptor.
C)B lymphocytes have MHCII protein,which binds to the viral gp42 protein.
D)The viral envelope glycoproteins are not processed correctly in B lymphocytes.
E)Lymphocytes have different lipids in their membranes,which inhibit fusion of the viral envelope.

Question 15

Which of the following is a disease NOT caused by a member of the herpesvirus family?

A)Cold sores.
B)Chickenpox
C)Common cold.
D)Encephalitis.
E)Hepatitis.

Question 16

The ICP27 protein from herpes simplex inhibits cellular gene expression by inhibiting mRNA splicing.

Question 17

Which of the following events during assembly of herpesvirus virions causes the scaffolding proteins to be ejected from the capsid?

A)Conformational change that seals the capsid.
B)Cleavage of the scaffolding proteins by a cellular protease.
C)Acquisition of the tegument around the capsid.
D)Insertion of the portal protein into one of the 12 vertices.
E)Packaging of the viral DNA into the capsid.

Question 18

Which of the following is NOT used a host cell receptor for herpes simplex virus?

A)Proteoglycans.
B)Nectin 1
C)Integrin
D)Heparan sulfate.
E)Herpesvirus entry mediator

Question 19

Which of the following viral glycoproteins from herpes simplex virus are involved with fusion of the envelope with the cellular plasma membrane?

A)gH and gL
B)gB
C)gC
D)gD
E)All of the above.

Question 20

What is unusual about the structure of the genome of herpes simplex virus?

A)It is a covalently closed circle.
B)It has two unique sequences flanked by inverted repeats
C)It has one long unique sequence flanked by terminal repeats.
D)It is linear with a terminal protein bound to each of the 5' ends.
E)It consists of two DNA segments.

Question 21

The EBER RNAs encoded by the Epstein-Barr virus are synthesizes by RNA polymerase III.

Question 22

Epstein-Barr virus particles produced in B lymphocyes will infect other B lymphocytes with a higher efficiency than they will infect epithelial cells.

Question 23

Explain the three models proposed for how newly assembled herpesvirus nucleocapsids exit the nucleus and acquire the tegument and envelope/

Question 24

The symptoms of mononucleosis,which include an enlarged spleen and fatigue,are caused by the expansion of infected B lymphocytes soon after primary infection.

Question 25

Describe what happens during a primary infection with herpes simplex virus I (HSVI),how the virus enters into latency,and then how the virus can be reactivated back to a lytic infection.Your answer should focus on the cell types affected by each stage of the infection.

Question 26

From an evolutionary perspective,herpesviruses have been very successful pathogens in the human population since they are so widely distributed and only cause severe disease in rare circumstances.Describe some of the biological characteristics of herpesviruses that have allowed them to be so successful.

Question 27

Both herpes simplex virus and Epstein-Barr virus have multiple mechanisms to suppress both cellular antiviral pathways as well as allow latently infected cells to hide from the adaptive immune system.Describe two of these mechanisms used by either virus.