Deck 18: Influenza Viruses

Question 1

Which of the following describes a difference between transcription and genome replication in the influenza virus?

A) Transcription requires the PB2 protein while genome replication does not.
B) Transcription produces a shorter positive strand mRNA while replication produces a full-length antigenome.
C) Transcription produces a poly(A) tail at the 3' end of the viral mRNA while genome replication does not.
D) Transcription requires a primer derived from a cellular pre-mRNA while genome replication does not.
E) All of the above are correct.

Answer 1

E

Question 2

Cleavage of the HA protein of influenza by cellular proteases is important for which of the following?

A) Activation of the fusion peptide.
B) Creation of the sialic acid binding site.
C) Release of the envelope proteins from the Golgi.
D) Attachment of the envelope to the capsid.
E) Insertion of the HA protein into the membrane.

Answer 2

A

Question 3

Treatment of influenza infected cells with actinomycin D and a-amanitin, which inhibit the activity of the cellular RNA polymerase II, shut down the synthesis of viral mRNAs.Which of the following describes the mechanism of this inhibition?

A) The viral RNA-dependent RNA polymerase is also inhibited by these compounds.
B) The virus needs a supply of nuclear pre-mRNAs to snatch caps from.
C) These inhibitors reduce the supply of nucleotides for transcription.
D) The cellular RNA polymerase synthesizes the viral mRNAs.
E) This leads to the degradation of the viral RNA genome segments.

Answer 3

B

Question 4

Virions of the influenza virus can be either spherical or filamentous in shape.

Question 5

Several of the protein from influenza virus interact with the cellular protein a-importin.Why is this necessary for virus infection?

A) It allows the viral proteins to by glycosylated in the Golgi.
B) It is important for entry of the viral genomes into the cell.
C) It transports the viral proteins to the plasma membrane.
D) It transports the viral proteins into the nucleus.
E) It is involved in fusion of the viral envelope with the endosome.

Question 6

Most animal influenza viruses do not infect humans.Which of the following can explain this observation?

A) Animal viruses fail to destroy ciliated epithelium in that host.
B) Animal viruses do not induce specific cytokines in the host.
C) Animal viruses bind to a different form of sialic acid than human viruses.
D) The HA proteins of animal viruses are activated by the protease furin.
E) Both c and d are correct.

Question 7

Which of the following describes the function of the M2 protein from influenza virus?

A) It induces the fusion of the viral envelope with the cell membrane.
B) It binds to the host cell receptor for viral entry.
C) It acts as an ion channel to allow H+ ions to enter the virion.
D) It helps to initiate transcription of viral mRNAs.
E) It cleaves off the 5' caps from the cellular mRNAs.

Question 8

Many of the symptoms caused by infection with the influenza virus, including fever, headache and malaise, are actually the result of which of the following?

A) Factors produced by the virus during infection.
B) Direct damage to the cells of the lung.
C) Infection of the liver.
D) Loss of ciliated epithelium.
E) The effect of cytokines induced by the virus.

Question 9

Most seasonal outbreaks of human influenza are caused by the influenza C virus.

Question 10

How is the poly(A)tail added to the 3' ends of the mRNAs produced during infection with a influenza virus?

A) The viral polymerase stutters at a poly(U) sequence.
B) The cellular poly(A) polymerase adds it.
C) Influenza virus mRNAs do not have poly(A) tails.
D) The viral poly(A) polymerase adds it after the mRNA is released from the template.
E) The entire poly(A) tail is encoded in the genome.

Question 11

Which of the following describes the function of the NS1 protein made during an influenza virus infection?

A) Inhibition of cellular antiviral defenses.
B) Activation of viral RNA polymerase.
C) Transport of nucleocapsids out of the nucleus.
D) Inhibition of cellular RNA polymerase.
E) Inhibition of antibody production.

Question 12

New reassorted influenza viruses are USUALLY transmitted to human from which of the following pathways?

A) A reassortment of two avian viruses that is directly transmitted from birds to humans.
B) A reassortment of an avian virus and a human virus that is transmitted from a pig.
C) A reassortment of two pig viruses that is directly transmitted from pigs to humans.
D) A reasortment of a human virus and a pig virus that is transmitted from a bird.
E) A reassortment of two human viruses that is directly transmitted from a human.

Question 13

The NS2 protein from influenza can bind and inhibit cellular proteins involved in polyadenlyation of mRNAs.Why doesn't this affect the virus?

A) Influenza virus mRNAs don't have poly(A) tails.
B) Influenza virus uses a stuttering mechanism to add the poly(A) tail.
C) All of the viral mRNAs are polyadenylated before the NS2 protein is made.
D) Influenza virus encodes its own poly(A) polymerase that isn't affected by NS2.
E) The virus encodes the poly(A) tail in the genome.

Question 14

What function does the neuraminidase protein of influenza virus carry out?

A) It binds to sialic acid and helps the virus enter the host cell.
B) It helps release virions from virus producing cells.
C) It is involved in the glycosylation process of the NA protein.
D) It cleaves the HA protein into two functional domains.
E) It helps the virus evade the immune system.

Question 15

While often confused with milder upper-respiratory infections caused by rhinoviruses and coronaviruses, the symptoms of influenza infection are more severe.

Question 16

Genome segments 7 and 8 from influenza virus can produce two different proteins using which of the following mechanisms?

A) Ambisense coding.
B) RNA editing.
C) Readthrough of a stop codon.
D) Alternative mRNA splicing.
E) Use of alternative start codons.

Question 17

Why are reassorted influenza viruses usually more likely to cause a severe worldwide pandemic?

A) They are more immunosuppressive than other influenza viruses.
B) They contain new segments that produce more pathogenic proteins.
C) They can infect different types of cells.
D) They have acquired new glycoproteins for which there is no prior immunity.
E) They have acquired mutations that allow them to evade the immune system.

Question 18

The abundance of which of the following proteins from influenza virus controls whether the virus is producing mRNAs or full-length positive antigenomes.

A) PB1 protein
B) PB2 protein
C) PA protein
D) Nucleocapsid protein.
E) Matrix protein

Question 19

Influenza produces 11 different proteins from 8 genome segments.How many of these proteins are packaged into the viral particle?

A) 7
B) 8
C) 9
D) 10
E) 11

Question 20

Which of the following viruses was responsible for the death of 20 million people in 1918-1920?

A) Ebola virus
B) Influenza virus
C) Smallpox virus
D) Rift Valley Fever virus
E) Measles virus

Question 21

Influenza is unusual for an RNA virus because it replicates in the nucleus.

Question 22

Influenza virus is one of the only RNA viruses that replicates in the nucleus of the host cell.How does this virus regulate transport of viral nucleocapsids into and out of the nucleus at various times during the infection?

Question 23

Explain the role that antigenic drift and shift play in the ability of influenza to cause new outbreaks.Which one is thought to have caused the 1918 strain of influenza to emerge?

Question 24

Influenza virus is unusual for an RNA virus because it replicates in the nucleus of the host cell.Describe the two processes that influenza uses the nucleus to accomplish.For which of these two is replication in the nucleus essential?

Question 25

During an influenza virus infection, the spliced mRNAs are produced in higher abundance than the unspliced mRNAs.

Question 26

Since influenza virus replicates in the nucleus of the infected cell, it uses the cellular polyadenlyation enzymes to add the poly(A)tail on the viral mRNAs.

Question 27

Prophylatic treatment of a patient with an antiviral drug to influenza is the best way to prevent infection.