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Table of Contents
Section I: Introduction to Virology
1. Introduction to Virology 2 Nicholas H. Acheson
2. Virus Structure and Assembly 18 Stephen C. Harrison
3. Virus Classification: The World of Viruses 31 Nicholas H. Acheson
4. Virus Entry 45 Ari Helenius
Section II: Viruses of Bacteria and Archaea
5. Single-Stranded RNA Bacteriophages 59 Jan van Duin
6. Microviruses 69 Bentley Fane
7. Bacteriophage T7 77 William C. Summers
8. Bacteriophage Lambda 85 Michael Feiss
9. Viruses of Archaea 97 David Prangishvili
Section III: Positive-Strand RNA Viruses of Eukaryotes
10. Cucumber Mosaic Virus 112 Ping Xu, Marilyn J. Roosinck
11. Picornaviruses 125 Bert L. Semler
12. Flaviviruses 137 Richard Kuhn
13. Togaviruses 148 Milton Schlesinger, Sondra Schlesinger, Richard Kuhn
14. Coronaviruses 159 Mark Denison, Michelle M. Becker
Section IV: Negative-Strand and Double-Stranded RNA Viruses of Eukaryotes
15. Paramyxoviruses and Rhabdoviruses 175 Nicholas H. Acheson, Daniel Kolakofsky,
Christopher Richardson, Laurent Roux
16. Filovirouses 188 Heinz Feldman, Hans-Dieter Klenk, Nicholas H. Acheson
17. Bunyaviruses 200 Richard M. Elliott
18. Influenza Viruses 225 Terence S. Dermody, James D. Chappell
19. Reoviruses 225 Terence S. Dermody, James D. Chappell
Section V: Small DNA Viruses of Eukaryotes
20. Parvoviruses 238 Peter Beard
21. Polyomaviruses 247 Nicholas H. Acheson
22. Papillomaviruses 263 Greg Matlashewski, Lawrence Banks
Section VI: Larger DNA Viruses of Eukaryotes
23. Adenoviruses 274 Philip Branton
24. Herpesviruses 285 Bernard Roisman, Gabriella Campadelli-Fiume, Richard Longnecker
25. Baculoviruses 302 Eric B. Carstens
26. Poxviruses 312 Richard C. Condit
27. Viruses of Algae and Mimivirus 325 Michael J. Allen, William H. Wilson
Section VII: Viruses That Use A Reverse Transcriptase
28. Retroviruses 342 Alan Cochrane
29. Human Immunodeficiency Virus Alan Cochrane
30. Hepadnaviruses 365 Christopher Richardson
Section VIII: Viroids and Prions
31. Viroids and Hepatitis Delta Virus 378 Jean-Pierre Perreault, Martin Pelchat
32. Prions 387 Dalius J. Briedis
Section IX: Host Defenses Against Virus Infection
33. Intrinsic Cellular Defenses Against Virus Infection 398 Karen Mossman, Pierre Geninm, John
Hiscott
34. Innate and Adaptive Immune Responses to Virus Infection 415 Malcolm G. Baines, Karen
Mossman
Section X: Antiviral Agents and Virus Vectors
35. Antiviral Vaccines 428 Brian Ward
36. Antiviral Chemotherapy Donald M. Coen
37. Eukaryotic Virus Vectors 456
Chapter Number: 01
Question type: Multiple Choice
1) Which of the following terms describes the protein shell that surrounds the viral genome?
a) capsid
b) envelope
c) matrix
d) virion
e) capsomer
eAnswer: a
2) Which of the following would not be a nucleic acid form found in a viral genome?
a) dsDNA
b) ssDNA
c) dsRNA
d) ssRNA
e) an RNA:DNA
hybridAnswer: e
3) Which of the following is an enzyme that most RNA viruses encode in their genome?
a) DNA-dependent-RNA-polymerase
b) RNA-dependent-RNA-polymerase
c) DNA-dependent-DNA-polymerase
d) DNA-dependent-RNA-polymerase
e) RNA-dependent-proteinsynthetaseAnswer: b
4) Viruses play a major role in the ecology of the ocean by doing which of the following?
a) By infecting photosynthetic bacteria and increasing their growth.
b) By infecting harmful bacteria found in the ocean and limiting their growth.
c) By killing off fish and preventing them from becoming too plentiful.
d) By lysing unicellular organisms and releasing carbon and oxygen back into the ocean.
e) All of the above statements are correct.
Answer: d
5) If you wanted to show that an infectious agent is a virus, what experiment could you do?
a) Show that the agent can be seen under a light microscope.
b) Show that agent contains a lipid membrane.
c) Show that the agent can form single colonies on an agar plate.
d) Show that the agent can be diluted and can still cause disease in an animal.
e) Show that the agent can pass through a porcelain filter and is still infectious.
Answer: e
6) What does the word “virus” mean in Latin?
a) infectious agent
b) liquid
c) poison
d) death
e) diseas
e
Answer:
c
7) The word “phage” is a shortened version of the name of a virus that can infect which type of
organism?
a) bacterial cell
b) human cell
c) eukaryotic cell
d) plant cell
e) inset
cell
Answer:
a
8) The study of which group of viruses led to the discovery of cellular genes that can promoter
cancer inanimal cells?
a) papillomaviruses
b) retroviruses
c) adneoviruses
d) polyomaviruses
e) picornaviruse
sAnswer: b
9) When doing a plaque assay with human or animal cells, a layer of nutrient media mixed with
agar is put on top of the cells after they have been infected with the diluted virus. What is the
major purpose ofthis agar layer?
a) It helps to feed the cells as they grow.
b) It promotes the replication of the virus.
c) It makes the infected cells easier to visualize.
d) It limits the movement of virus particles.
e) All of the above are correct.
Answer: d
10) To start an experiment, you do an infection by putting 0.5 ml of a virus stock that has a titer
of 6 x 107 pfu/ml onto a plate of animal cells that contains 5 x 106 cells. What is the multiplicity
of infection forthis experiment?
a) 12
b) 6
c) 5
d) 3
e) 1
Answer:
b
11) During a single growth cycle experiment, the titer of extracellular and intracellular virus
drops in thefirst hour. What explains this observation?
a) The virus is inactivated by antibodies in the medium.
b) The virus is inactivated by cellular enzymes.
c) The virus enters the cell and is uncoated.
d) The virus binds to the cells in the dish and can’t be released.
e) The cell’s antiviral defenses prevent replication of the virus
Answer: c
12) What is another term for an RNA-dependent-DNA-polymerase?
a) DNA polymerase
b) RNA polymerase II
c) RNA replicase
d) RNA transcriptase
e) Reverse
transcriptaseAnswer:
e
13) Plant viruses use which cellular structures to spread between host cells?
a) endosomes
b) plasmodesmata
c) plasma membranes
d) vesicles
e) receptor
sAnswer:
b
14) All viruses that use a negative-sense RNA genome must package which of the following
proteins intheir virion?
a) RNA-dependent-RNA-polymerase
b) matrix protein
c) RNA helicase
d) RNA methylase
e) scaffolding
proteinAnswer: a
15) Which of the following is a description of a plaque?
a) A viral particle as seen by electron microscopy.
b) A region of dead cells in a monolayer of infected cells.
c) A skin lesion caused by a virus infection in an animal.
d) A button of red blood cells seen in a hemagglutination assay.
e) A region of crystallized virus particles in an infected cell.
Answer: b
16) Which of the following processes in cells was NOT discovered by studying a virus?
a) the sequence of the genetic code.
b) DNA replication in both prokaryotic and eukaryotic cells
c) DNA is the genetic material
d) regulation of gene expression in eukaryotic cells.
e) mRNA splicing in eukaryotic cells
Answer: a
17) You are given a solution of virus and asked to determine the titer. You carry out a plaque
assay with0.5mls of a 105 dilution of the virus solution and obtain an average of 150 plaques.
What is the titer of the solution?
a) 1.5 x 105 pfu/ml
b) 3 x 105 pfu/ml
c) 1.5 x 107 pfu/ml
d) 3 x 107 pfu/ml
e) 1.5 x 108
pfu/mlAnswer:
d
18) The Baltimore classification system describes the relationship between a viral genome and
the:
a) the complementary genome sequence.
b) early viral proteins.
c) early mRNAs.
d) cellular polymerases.
e) Latin classification system.
Answer: c
19) If the genome of a positive-strand RNA virus, which has been purified away from all of
the virionproteins, was injected into the cytoplasm of an appropriate host cell, what would
happen first?
a) The genome would be copied into complementary negative RNA.
b) The genome would be translated by cellular ribosome’s.
c) The genome would be transcribed by a cellular RNA-dependent-RNA-polymerase.
d) The genome would be transcribed by a viral RNA-dependent-RNA-polymerase.
e) None of the above.
Answer: b
20) If the genome of a negative-strand RNA virus, which has been purified away from all of
the virionproteins, was injected into the cytoplasm of an appropriate host cell, what would
happen first?
a) The genome would be copied into complementary negative RNA.
b) The genome would be translated by cellular ribosome’s.
c) The genome would be transcribed by a cellular RNA-dependent-RNA-polymerase.
d) The genome would be transcribed by a viral RNA-dependent-RNA-polymerase.
e) None of the above.
Answer: e
21) Most DNA viruses that replicate in the nucleus of the host cell use which of the
following totranscribe their genes into mRNA?
a) cellular DNA-dependent-RNA polymerase
b) viral DNA-dependent-RNA polymerase
c) viral DNA-dependent-DNA polymerase
d) cellular DNA-dependent-DNA polymerase
e) viral RNA-dependent-DNA
polymeraseAnswer: a
22) The development of which of the following instruments or techniques in the 1930’s allowed
scientists to visualize viral particles for the first time?
a) polymerase chain reaction
b) electron microscope
c) confocal microscope
d) thermal cycler
e) plaque
assay
Answer: b
Question Type: True/False
24) The common cold can be caused by viruses from three different families, some of which
have RNAgenomes and some of which have DNA genomes.
Answer: True
25) The major advantage of a hemagglutination assay to measure the amount of virus
particles in asolution is that it is very accurate.
Answer: False
26) Phages, viruses that can infect bacterial cells, may someday be used to treat bacterial
infections.
Answer: True
Question type:
Essay
27) The particle to plaque ratio for most animal viruses is much greater than one. What are the
reasons why not 100% of animal virus particles, as seen under the electron microscope, can
productively infect cells?
Answer: Not all virus particles as seen under the electron microscope are intact virions
capable of binding and entering a host cell. Some virus particles contain defective genomes
that lack one or morecritical genes necessary for viral replication. Some viral particles contain
empty capsids, which means that there is not genome inside the virion. Finally, cells have
many antiviral defense mechanisms that can shut down a virus infection before it can be
completed.
28) Viruses are not the only obligatory intracellular parasites. Describe how the replication of
viruses is different than cellular organisms that replicate inside of cells, like chlamydiae and
rickettsiae.
Answer: Unicellular parasitic cells that need to replicate inside of other cells do not replicate in
the sameway that viruses do. First of all, unicellular parasites have their own ribosomes to
translate their mRNAs and do not use the host cell ribosomes, like viruses do. In addition they
are intact cells that contain theirgenome entirely within their own cellular membranes and do not
release their genome into the host cell, the way that viruses do. These cellular parasites
undergo binary fission in the same way that independently living cells do. Viruses do not have
their own ribosomes and actually disintegrate their virion, releasing the genome out of the
capsid and into the cytoplasm before they begin their replication. They do not undergo binary
fission.
Package Title: Testbank
Course Title: Acheson 2nd
editionChapter Number: 02
Question type: Multiple Choice
1) The lipid membrane that surrounds the nucleocapsid of some virus particles is called the:
a) matrix
b) tegument
c) capsid
d) envelope
e) glycoprotei
nAnswer: d
2) The nucleocapsid describes the structure that includes the:
a) capsid and the genome
b) capsid and the envelope
c) envelope and the glycoproteins
d) helical capsid and an envelope
e) icosahedral capsid and an
envelopeAnswer: a
3) Depending on the type of virus, which of the following is a function of the virus capsid?
a) To attach to the correct type of host cell.
b) To protect the viral genome from nucleases.
c) To ensure delivery of the genome into the host cell.
d) To protect the viral genome from damage by UV light.
e) All of the above functions are correct.
Answer: e
4) Virus particles can be visualized with which of the following?
a) negative staining of virions with electron microscopy
b) negative staining of virions with x-ray diffraction
c) negative staining of thin sections of infected cells with electron microscopy
d) positive staining in cryoelectron microscopy
e) positive staining of infected cells with x-ray
diffractionAnswer: a
5) Most viruses that use a spherical shaped capsid arrange their capsid proteins with
which of thefollowing symmetries?
a) cubic
b) tetrahedral
c) icosahedral
d) dodecagon
e) helical
Answer:
c
6) Which of the following is NOT a characteristic of a regular icosahedron?
a) It has 12 vertices of 5-fold symmetry.
b) It has 20 triangular faces.
c) It has 20 sides with 3-fold symmetry.
d) It has 30 edges with 2-fold symmetry
e) It has 6 square faces.
Answer: e
7) How many copies of the capsid protein would there be in an icosahedral capsid with a
Triangulationnumber of 7?
a) 70
b) 210
c) 280
d) 420
e) 490
Answer: d
8) Which of the following h and k values will produce a triangulation number of 13?
a) 1 and 1
b) 1 and 2
c) 1 and 3
d) 2 and 3
e) 2 and
4
Answer:
c
9) The capsid of SV40 contains 360 protein copies. Why is this unusual?
a) There is only 1 kind of protein in this capsid.
b) 360 is not the correct number of protein capsids for a T = 6 capsid.
c) Six is not a mathematically allowed triangulation number.
d) The proteins have equivalent interactions.
e) The capsid is not large enough to hold the entire genome.
Answer: c
10) The Jelly Roll
barrel is:
a) a structure found in many viral envelope glycoproteins.
b) a structure found in many viral capsid proteins.
c) the structure the viral genome takes inside of a helical capsid.
d) the structure the viral genome takes inside an icosahedral capsid.
e) the structure of many helical capsids as the wrap around the genome.
Answer: e
11) Which of the following describes the number of subunits per turn in a helical capsid?
a) P (pitch)
b) (mu)
c) (rho)
d) Triangulation number
e) symmetr
yAnswer:
b
12) A very common structure for bacteriophage particles is which of the following?
a) an icosahedral head and an envelope
b) a naked icosahedral head
c) a naked helical tail
d) an icosahedral head with a helical tail
e) a cubic head with a helical
tail Answer: d
13) A Type I membrane protein has which of the following structures?
a) Both the C-terminus and the N-terminus face the inside of the virion.
b) It passes through the viral envelope multiple times.
c) The N-terminus faces outside the virion and the C-terminus faces inside the virion.
d) The N-terminus faces inside the virion and the C-terminus faces outside the virion.
e) The protein lacks a transmembrane domain and is secreted from the infected cell.
Answer: c
14) What does the term “quasi-equivalent” mean with respect to the proteins in an icosahedral
capsid?
a) If the identical protein is used, it has both 5-fold and 6-fold interactions with the other proteins
in thecapsid.
b) There are different proteins in the capsid with similiar shapes.
c) They all use the “jelly-roll” protein structure.
d) There can be more than one type of glycoprotein in the envelope.
e) All of the proteins interact in a 5-fold arrangement.
Answer: a
15) Which of the following is a description of a scaffolding protein?
a) A cellular protein that acts as a chaperone during assembly of a helical capsid.
b) A viral protein that is used on the outside of an icosahedral capsid during assembly.
c) A viral protein used on the inside of an icosahedral capsid during assembly and then removed.
d) A protease that trims the proteins during assembly of an icosahedral capsid.
e) A energy dependent motor used to package the genome into larger icosahedral capsids.
Answer: c
16) A scaffolding protein is important for assembly of an icosahedral capsid…..
a) but does not bind to the viral genome.
b) but does not become part of the final virion.
c) and helps to cut the genome into unit lengths.
d) and binds to the host cell receptor.
e) and assists the virion in exiting the host cell.
Answer: b
17) A packaging sequence is involved in which of the following assembly processes?
a) The assembly of the capsid around the genomic nucleic acid.
b) The correct binding of capsid proteins to each other.
c) The insertion of the viral glycoproteins in the envelope.
d) The acquisition of the envelope by the capsid.
e) The packaging of the matrix proteins into the virion.
Answer: a
18) In a helical nucleocapsid, which of the following MOST affects the LENGTH of the capsid?
a) the (mu) value
b) the (rho) value
c) the size of the genome and the P (pitch) of the helix
d) the size of the capsid protein
e) None of the above.
Answer: c
19) Enveloped virions assemble and acquire their envelope by which of the following
mechanisms?
a) The nucleocapsids interact directly with the cytoplasmic tails of the envelope glycoproteins
and budthrough the cellular membrane.
b) The nucleocapsids interact with the matrix protein, which interact with the cytoplasmic tails
of theenvelope glycoprotein, and the virion buds through the cellular membrane.
c) The envelope is assembled de novo around the nucleocapsid by cellular enzymes.
d) The virion acquires the envelope after it leaves the host cell from extracellular vesicles.
e) Both a and b are used by viruses.
Answer: e
20) Viral proteins that assemble between the nucleocapsid and the envelope are called
a) matrix proteins
b) envelope glycoproteins
c) scaffolding proteins
d) core proteins
e) packaging proteins
Question Type:
True/False
21) It is possible to get high resolution images of enveloped virus particles using x-ray diffraction.
Answer: False
22) Some viruses particles have a rigid capsid surrounding an internal membrane.
Answer: True
23) Cryoelectron microscopy uses computer reconstruction of images of multiple virions to
produce ahigh resolution image of a virion or capsid.
Answer: True.
24) Viral envelopes often have very different lipid compositions than the cellular membranes
that theyoriginate from.
Answer: False
Question type:
Essay
25) Describe the concept of “quasi-equivalence” as it applies to icosahedral capsid structure.
Answer: Quasi-equivalence describes the situation in icosahedrons with triangulation numbers
higher than 1 and that use a single protein to assembly their capsid. In these capsids, the
protein must interactin a 5-fold symmetry at the 12 vertices and in a 6-fold symmetry in the
hexagonal faces. Therefore its interactions are not always identical but depend on the protein’s
location within the capsid.
26) Virions are often described as being energetically “metastable”. What does this mean and
why is it
important for entry and uncoating of the viral genome into the next host cell?
Answer: Virons are described as “metastable” because they are not at their lowest, most
stable, energy state. If they were, they would not be able to “pop open” to release the genome
in the next host cell. Instead, they are like a “Jack-in-the-box”, primed to spring open and
release the genome after some triggering event. The triggering event that causes the virion to
open and release the genome is often theinteraction with the host cell receptor or some other
change, like a drop in pH, that occurs during attachment and entry. Often proteolytic cleavage of
a virion protein is involved in setting up the
metastable state and “setting the spring” that will eventually allow the virion to pop open.
Package Title: Testbank
Course Title: Acheson 2nd
editionChapter Number: 03
Question type: Multiple Choice
1) Which of the following types of genomes is most commonly found in viruses that can infect
fungi?
a) ssDNA
b) dsDNA
c) ssRNA
d) dsRNA
e) All of the above are found.
Answer: d
2) The name of a virus family in the Latin classification system has which of the following
endings?
a) -viridae
b) -virales
c) -virinae
d) -virus
e) virusdae
Answer: a
3) The family classification scheme for DNA bacteriophages is not very useful for
describing theevolutionary relationships between these viruses. What is the best
explanation for this?
a) DNA bacteriophages can infect more than one host species.
b) DNA bacteriophages have a wide variety of virion structures.
c) The viral genomes are genetic mosaics due to recombination.
d) There are too many bacteriophages to classify into families.
e) These viruses do not have an evolutionary relationship to each other.
Answer: c
4) Which of the following is a type of nucleic acid NOT found as the genome of a virus that
can infectvertebrates?
a) ssDNA
b) dsDNA
c) ssRNA
d) dsRNA
e) All of the above are found.
Answer: e
5) Most viruses that infect plants have the following type of genome?
a) ssDNA, positive sense
b) ssDNA, negative sense
c) ssRNA, positive sense
d) ssRNA, negative sense
e) None of the above.
Answer: c
6) What is a possible explanation for why ssDNA viruses have genomes less that 10kb in size?
a) ssDNA is not as physically stable as dsDNA.
b) ssDNA is not transcribed by host cells.
c) ssDNA can form hairpin structures because of base-pairing.
d) Larger pieces of ssDNA can not be replicated.
e) Larger pieces of ssDNA can not easily enter the host cell.
Answer: a
7) An interesting observation is that many highly pathogenic and deadly human viruses
have thefollowing type of genome?
a) ssDNA, positive sense
b) ssDNA, negative sense
c) ssRNA, positive sense
d) ssRNA, negative sense
e) dsRN
A
Answer:
d
8) Which of the following virus families have the ability to synthesize reverse transcriptase?
a) Retroviruses
b) Caulimoviruses
c) Hepadnaviruses
d) None of the above are correct.
e) All of the above are correct.
Answer: e
9) What distinguishes a satellite virus from a satellite nucleic acid?
a) A satellite virus encodes its own capsid protein while a satellite nucleic acid does not.
b) A satellite virus packages its own replication protein while a satellite nucleic acid does not.
c) A satellite virus requires a helper virus while a satellite nucleic acid does not.
d) Genomes of satellite viruses are smaller than those of satellite nucleic acids.
e) Satellite viruses do not encode any proteins while satellite nucleic acids do.
Answer: a
10) What is a ribozyme?
a) A molecule of RNA that is independently capable of replicating without cellular enzymes.
b) A molecule of RNA that codes for an enzyme.
c) Another name for a small infectious molecule of RNA
d) A virus that uses a small piece of RNA as its genome.
e) A molecule of RNA that can carry out an enzymatic process.
Answer: e
11) According to the RNA World hypothesis, which of the following subcellular entities
may haveevolved first?
a) Retroviruses
b) RNA Viruses
c) Viroids
d) DNA Viruses
e) Bacteriophag
esAnswer: c
12) According to the RNA World hypothesis, which of the following enzymes may have evolved
first?
a) DNA-dependent RNA polymerase
b) DNA-dependent DNA polymerase
c) RNA-dependent RNA polymerase
d) RNA-dependent DNA polymerase
e) self-replicating
RNAsAnswer: e
13) Which of the following virus families contains viruses with the longest ssRNA genomes?
a) Picornaviruses
b) Coronaviruses
c) Flaviviruses
d) Togaviruses
e) Bromoviruse
sAnswer: b
14) What is approximately the largest size of a double-stranded DNA genome of a virus
that infectvertebrates?
a) 25 kbp.
b) 50 kbp
c) 100 kbp
d) 300 kbp
e) 500
kbp
Answer:
d
15) Almost all of the viruses with positive-strand RNA genomes and enveloped virions
infect whichgroup of hosts?
a) Bacteria.
b) Vertebrates
c) Plants
d) Fungi
e) Algae.
Answer: b
16) Which of the following may be a factor in explaining why viral ssRNA genomes are not
usually aslong as the dsDNA genomes?
a) It is much more difficult to package a large ssRNA genome into a capsid.
b) Long ssRNA molecules form too many secondary structures that inhibit replication.
c) Long RNA genomes are difficult to translate.
d) Long RNA genomes are difficult to transcribe.
e) Long pieces of RNA are easily broken by mechanical damage.
Answer: e
17) The advantage of using a helical instead of an icosahedral nucleocapsid to package a ssRNA
genome
is…..
a) it is more efficient to envelope a helical nucleocapsid than an icosahedral capsid.
b) it is easier to produce a helical nucleocapsid than an icosahedral capsid.
c) it better protects the genome from degradation inside the cell.
d) it requires a smaller protein to build than an icosahedral capsid.
e) it requires fewer copies of the nucleocapsid protein than an icosahedral capsid.
Answer: c
18) There are a number of small DNA viruses that are highly dependent on their host cells for
transcription and replication enzymes. Which of the following could explain the evolutionary
origins ofthese viruses?
a) They originated from fragments of the genomes of larger more independent viruses.
b) They originated from intracellular plasmids found in bacteria.
c) They originated from the genomes of intracellular organelles, such as mitochondria.
d) They originated from fragments of cellular DNA that broke away from the cell genome.
e) All of the above could be correct.
Answer: d
19) The RNA World hypothesis is supported by the observation that:
a) there are viruses that still use RNA as their genomic nucleic acid.
b) some viruses can covert RNA to DNA.
c) some RNA molecules have enzymatic activity.
d) some viruses encode RNA-dependent RNA polymerases.
e) All of the above support the RNA World hypothesis.
Answer:
20) Which of the following characteristics are NOT one of the most important criterion used to
classifyviruses into families?
a) topology of genome (linear or circular)
b) strandedness of genome (double or single stranded)
c) type of nucleic acid used in genome (DNA or RNA)
d) structure of virion
e) species of host
infectedAnswer: e
Question Type: True/False
21) There are several types of viruses with enveloped virions that can infect plants.
Answer: False
22) Retroviruses are the only virus family known to package two copies of its genome.
Answer: True.
23) Viroids do not require a helper virus in order to replicate and cause disease.
Answer: True
Question type:
Essay
24) Why is the type of disease caused not the best criteria to use when classifying a virus?
Answer: The disease caused by a specific virus is not usually related to the evolutionary
history of thatvirus. Viruses with very different types of genomes, virion structures, and
replication pathways can cause the same type of disease. For example, there are at least 5
different viruses that cause a form ofhepatitis in humans and these viruses are in 5 different
families. Families, which are based on genomeand virion structure, represent evolutionary
relationships between viruses.
25) Mimivirus, which infects an amoeba, is the largest known dsDNA virus and has a genome
larger than some free living bacteria and archae. Even though it encodes many of its own
enzymes and even tRNAs, it still does not produce its own ribosomes. Describe the possible
evolutionary origin of such a large andcomplex viruses.
Answer: Mimiviruses, along with poxviruses, are thought to have possibly once been
independently replicating cells that lost the ability to make their own ribosomes and took on an
intracellular parasitic life style. These viruses are capable of synthesizing and processing their
mRNAs using mechanisms very
similar to those used by the host cell. Another hypothesis is that they may have been
precursors to theeukaryotic cell nucleus by at one point becoming incorporated into a
prokaryotic cell.
Package Title: Testbank
Course Title: Acheson 2nd
editionChapter Number: 04
Question type: Multiple Choice
1) Before the viral genome can be transcribed or replicated in a new host cell it must….
a) be trimmed by cellular nucleases.
b) be transported through the receptor mediated endocytosis pathway.
c) be processed through the cellular exocytosis pathway.
d) enter the host cell nucleus and be bound by cellular histone proteins.
e) be uncoated in the appropriate compartment of the correct cell type.
Answer: e
2) Unenveloped viruses must get their genome past the hydrophobic cell membrane. Some
accomplishthis by doing which of the following?
a) They cause the plasma membrane to lyse.
b) They insert viral proteins into a vesicle membrane.
c) They inject their genome into the nucleus via the nuclear pore complex
d) They create a pore through the membrane and extrude the genome directly into the cytoplasm
e) They create a clatherin coated pit during
entryAnswer: d
3) Because of the rigid plant cell wall, the entry of plant viruses is difficult. Which of the
following is adescription of how plant viruses move between individual cells within in a whole
plant?
a) They move between cells using plasmodesmata.
b) They cause the formation of syncytia.
c) They use the receptor mediated endocytosis pathway.
d) They rely on insect vectors to transfer virions between the cells in a single host.
e) They produce movement proteins that can create holes in the plant cell wall, allowing
movement ofthe virions between cells.
Answer: a
4) Which of the following is the best description of a syncytia?
a) A cellular structure that viruses us to move within a host cell.
b) A fusion of two cells causes by viral envelope glycoproteins.
c) A structure between two plant cells that viruses can use for cell to cell movement.
d) A vesicle involved in the receptor mediated endocytosis pathway.
e) A protein that is involved in the transport of proteins into the nucleus.
Answer: b
5) Orthymyxoviruses and paramyxoviruses both bind to which receptor on the surface of
which hostcells?
a) an immunoglobulin family receptor protein
b) the CD4 protein
c) the carbohydrate sialic acid
d) the neuraminidase enzyme
e) a multiple membrane spanning transport
proteinAnswer: c
6) Which of the following is an example of a virus that requires two different host cell
receptors tocomplete its entry into the host cell?
a) HIV-1
b) Adenovirus
c) Polio (picornavirus)
d) Influenza virus (orthomyxovirus)
e) Both HIV an Adenovirus require two cell receptors for entry.
Answer: e
7) Which of the following organelles is used as a sorting and recycling station in the receptor
mediatedendocytosis pathway?
a) Early endosome.
b) Clatherin-coated vesicle.
c) Lysosome.
d) Golgi apparatus.
e) Caveola
eAnswer:
a
8) Most viruses must exit the endosome before it fuses with a lysosome. Why?
a) Their envelope will not fuse easily with the lysosomal membrane.
b) To avoid the very low pH in the lysosome, which causes destructive conformational changes.
c) To avoid being degraded by lysosomal proteases and nucleases.
d) To enhance their movement towards the nucleus of the cell.
e) The pH of the lysosome is too high to induce membrane fusion.
Answer: c
9) Which of the following is an accurate description of cavelolae?
a) Small, flask-shaped invaginations of the plasma membrane enriched in cholesterol.
b) Vesicles surrounded by a cage of clatherin proteins.
c) Regions of the plasma membrane rich in cell signaling molecules.
d) A cytoskeletal network that is involved in transport of vesicles to the nucleus.
e) A cellular motor protein that is involved in intracellular transport.
Answer: a
10) The major different between class I fusion proteins and class II fusion proteins is that ….
a) class I protein mediate fusion at the plasma membrane and class II protein mediate fusion
with theendosome membranes.
b) only class I proteins contain fusion peptides.
c) only class II proteins have a transmembrane domain.
d) only class I proteins undergo large conformation changes within the protein during entry.
e) class I proteins are found in unenveloped virus particles while class II proteins are found in
envelopedparticles.
Answer: d
11) Adenoviruses use which of the following entry mechanisms?
a) The fibers on the virion can penetrate the endosome membrane can cause it to lyse open.
b) An interaction between the penton base of the virus and the cellular integrin proteins
causes theendosome membrane to lyse open
c) The capsid forms a pore through the cell membrane and extrudes the genome into the
cytoplasm
d) The viral envelope fuses at the plasma membrane after binding to the host integrin protein.
e) The viral envelope fuses with the nuclear membrane after binding to the nuclear pore complex.
Answer: b
12) Inhibition of the M2 protein of influenza with the drug amantadine will block which step
of virusentry?
a) fusion of the viral envelope with the endosome membrane.
b) movement of the RNA genome segments through the nuclear pore
c) the conformational change that the HA proteins exhibit in response to the drop in pH
d) binding to sialic acid on the surface of the host cell
e) unpacking of the viral RNA genome segments from the
virion Answer: e
13) Why would some viruses have the enzyme neuraminidase, which can cleave their receptor
sialic acidfrom membranes, in their envelopes?
a) It removes sialic acid from the viral envelope so that it doesn’t interfere with binding to the
next hostcell.
b) It allows virions to mature their envelope proteins so that they can attach to the next host cell.
c) It prevents the virions from attaching to dead cells, which would not lead to a productive
infection.
d) It removes sialic acid from the host cell membranes, which exposes their high affinity
proteinreceptor.
e) It allows the released virus particles to move more easily through the extracellular matrix.
14) Many large DNA viruses use which of the following cellular components to get their
nucleocapsidnear to the host cell nucleus
a) intermediate filaments
b) nuclear pore complex
c) actin filaments
d) microtubules
e) importin
sAnswer:
d
15) What mechanism do most retroviruses, but not HIV, use to get their genome into the
host cellnucleus?
a) They actively inject their genome into the nucleus through the nuclear pore complex.
b) These viruses do not need to enter the nucleus to replicate.
c) They attach their genome to importin proteins which carry them into the nucleus.
d) They wait until the cell enters mitosis and the nuclear envelope breaks down.
e) The genome is bound to viral proteins that contain nuclear localization signals that move the
genomethrough the nuclear pore complex.
Answer: d
16) Which of the following describes the function of dynein?
a) It is a protein involved in importing cargo into the nucleus through the nuclear pore complex.
b) It is a motor protein that moves along microtubules towards the nucleus.
c) It is a motor protein that moves along microtubules towards the cell periphery.
d) It is a cell structure used to pass virus particles directly between host cells.
e) It a cellular membrane protein used as a cell receptor by many viruses.
Answer: b
17) Which of the following statements is a good explanation for the observation that many
differentrhinovirus strains can all use the same host cell receptor?
a) The receptor binding site is buried at the base of a narrow canyon on the viral capsid
which isinaccessible to antibody proteins.
b) The recptor binding site is the most exposed area of the capsid which is highly accessible to
antibodyproteins.
c) The amino acid sequence of the canyon region of the capsid is highly variable.
d) The amino acid sequence on the antibody exposed surfaces of the capsid is highly variable.
e) The amino acid sequence on the exposed areas of the capsid are highly conserved in each
strain.
Answer: a
18) A soluble form of the CD4 protein was once investigated as a treatment for HIV
infection. Howwould this protein work to block infection.
a) It would raise the pH of the endosome and prevent activation of the fusion protein.
b) It would bind to the cell membrane and prevent fusion of the HIV virion with the plasma
membrane.
c) It would interact with the host cell receptor and prevent binding by the virion glycoproetin.
d) It would interact with the HIV envelope glycoprotein and block its interaction with the
host cellreceptor.
e) It would inhibit entry of the viral genome into the cell nucleus.
Answer: c
19) As part of an experiment, you take a solution of purified influenza virus particles and lower
the pH ofthe solution to 5.5. You then add the virus to a culture of the appropriate host cell.
What do you think would happen?
a) The HA protein would become inactivated and the virus would not be able to enter the host
cell.
b) The viral genome would be degraded and the virus would not be able to start the infection.
c) The HA protein would be able to bind more tightly to the host cell receptors.
d) The cell would not be able to take up the virus particles into clatherin coated pits.
e) The virus particles would not be able to be transported into the nucleus.
Answer: a
Question Type: True/False
20) The interaction between the viral particle and the host cell receptor is a major determinant
of thespecies specificity of viral infections.
Answer: True
21) Most DNA viruses replicate in the cytoplasm of the host cell, since the ribosomes they
need totranslate their mRNAs are located in this cellular compartment.
Answer: False
22) It would be correct to say that in a topological sense the nucleocapsid of an enveloped
virion hasnever left the cytoplasm of a host cell.
Answer: True
23) The diameter of the opening in the nuclear pore complex is much too narrow to allow
passage ofany virus particles directly into the nucleus.
Answer: False
Question type:
Essay
24) Enveloped viral particles require activation energy in order to penetrate the host cell.
Describe thetwo events that these viruses can use to provide this activation energy.
Answer: Some enveloped viruses use the interaction between the host cell receptor and an
envelopeglycoprotein, which induces a conformational change in the viral glycoprotein and
provides the necessary energy for fusion. Other viruses require the drop in pH that occurs in
endosomes, which causes conformation changes in the viral glycoproteins and provides
energy for membrane fusion.
25) Describe what a fusion peptide is and how it is involved in mediating membrane fusion
between theviral envelope and the cell membrane?
Answer: A fusion peptide is a hydrophobic 10-12 amino acid region at the N-terminus of the
transmembrane subunit of an viral envelope glycoprotein. During entry of an enveloped virus,
the viralglycoprotein is activated by either binding to the host cell receptor or the drop in pH in
the endosome. This activation causes a conformational changes or rearrangement in the
glycoprotein and exposes the
fusion peptide. This peptide is then inserted into the host cell membrane and mediates
fusion of theviral envelope with the host membrane.
Package Title: Testbank
Course Title: Acheson 2nd
editionChapter Number: 05
1) Which of the following structures found on E. coli cells is required for infection with a
ssRNAphage?
a) Cell wall
b) Lipopolysaccharide
c) F-pili
d) Cell surface receptor
e) All of the above are required.
Answer: c
2) The discovery of the ssRNA phages was useful to scientists working on
which of thefollowing processes:
a) Structure of ribosomal RNA
b) Translation of messenger RNA
c) Structure of proteins
d) Transcription of messenger RNA
e) Replication of
DNAAnswer: b
3) Why are ssRNA phages used as an index organism to detect the presence of
pathogenicenteroviruses in the sewage treatment process?
a) The RNA phage are smaller than the pathogenic viruses.
b) The RNA phage are easier to inactivate than the pathogenic viruses.
c) The RNA phage are more stable than the pathogenic viruses.
d) The RNA phage are easier to quantify using a plaque assay than the pathogenic
viruses.
e) The RNA phage are easier to see with an electron microscope than the
pathogenic viruses Answer: d
4) Translational readthrough occasionally occurs in the coat protein gene of the
ssRNA phageQ . Which of the following describes this process?
a) The stop codon (UGA) is read as a tryptophan codon (UGG).
b) The RNA-dependent RNA polymerase reads into the next gene.
c) The RNA-dependent RNA polymerase inserts an extra base in this gene.
d) The ribosome shifts back one base and reads a different reading frame.
e) The ribosome shifts forward one base and reads a different reading frame.
Answer: a
5) How is the structure of an RNA phage virion different from the structure of the virion
of manydsDNA phages?
a) They have much shorter tails than the DNA phages.
b) The heads do not use icosahedral symmetry.
c) The icosahedral head has a very large triangulation number.
d) They are solely composed of a helical nucleocapsid.
e) They lack the tail structure used to inject the genome into the host cell.
Answer: e
6) Which of the following proteins in the virions of the ssRNA phages binds to the
F-pilusduring virus attachment and entry?
a) Lysis protein
b) Attachment protein
c) Coat protein
d) Maturation protein
e) Replicase
proteinAnswer: d
7) When an RNA phage virion is assembled with either a defective or missing
maturationprotein, which of the following occurs?
a) The viral RNA genome is more sensitive to RNAse degradation.
b) The virion is more sensitive to protease degradation.
c) The virion is unstable and disassembles easily in the environment.
d) The virion is not able to carry out genome replication.
e) The tail cannot inject the genome into the host cell.
Answer: a