A virus has attached to a host cell, penetrated the plasma membrane, and released its genome into the cytoplasm. These events are part of which phase of viral replication?
A. Early phase
B. Late phase
C. Eclipse period
D.
Latent period
A. Early phase
Delivery of the viral genome to the nucleus belongs to which phase?
A. Assembly phase
B. Release phase
C. Late
phase
D. Early phase
D. Early phase
Which event marks the beginning of the late phase of the viral replication cycle?
A. Attachment to the host-cell receptor
B. Viral genome
replication
C. Penetration of the plasma membrane
D.
Uncoating of the viral genome
B. Viral genome replication
Which sequence occurs during the late phase of viral replication?
A. Attachment → penetration → uncoating
B. Receptor
recognition → nuclear entry → uncoating
C. Genome replication →
macromolecular synthesis → assembly → release
D. Release →
attachment → genome replication → assembly
C. Genome replication → macromolecular synthesis → assembly → release
A host cell contains viral nucleic acids and proteins, but no
newly assembled virions are yet detectable. The virus is
currently in which period?
A. Latent period only
B.
Eclipse period
C. Release period
D. Extracellular period
B. Eclipse period
Which event marks the end of the eclipse period?
A. Attachment
of the virus to the host cell
B. Release of new viruses from the
host cell
C. Appearance of newly assembled virions
D.
Entry of the viral genome into the nucleus
C. Appearance of newly assembled virions
Which event marks the end of the latent period?
A. Release of
newly produced viruses
B. Appearance of assembled intracellular
virions
C. Beginning of viral genome replication
D.
Uncoating of the viral genome
A. Release of newly produced viruses
How are the eclipse and latent periods related?
A. The eclipse
period begins after the latent period ends
B. The two periods
are identical and end with viral assembly
C. The latent period
occurs entirely within the eclipse period
D. The latent period
includes the eclipse period
D. The latent period includes the eclipse period
Viral particles contain defective genomes and compete with normal
viruses for host-cell replication machinery. What are these particles
called?
A. Temperate bacteriophages
B. Defective
interfering particles
C. Proviruses
D. Viroids
B. Defective interfering particles
Which description of defective interfering particles
is most accurate?
A. They always contain complete viral genomes
but lack capsids
B. They are normal virions that cannot bind
host-cell receptors
C. They are host-cell vesicles containing
viral proteins
D. They may contain defective genomes or may be
empty virions
D. They may contain defective genomes or may be empty virions
A mutation prevents a viral attachment protein from interacting with its corresponding host-cell molecule. Which step of viral replication is most directly impaired?
A. Uncoating
B. Attachment
C. Assembly
D. Release
B. Attachment — Viral attachment proteins (VAPs) bind specific receptors on the target cell.
Which entry mechanism is normally used by most nonenveloped viruses?
A. Fusion with the nuclear membrane
B. Budding through the plasma membrane
C. Fusion with the cellular membrane
D. Receptor-mediated endocytosis or viropexis
D. Receptor-mediated endocytosis or viropexis
An enveloped virus binds its receptor and then delivers its nucleocapsid directly into the cytoplasm. Which process most likely allowed this entry?
A. Fusion of the viral envelope with a cellular membrane
B. Passage through a bacterial secretion system
C. Replication within an endocytic vesicle
D. Destruction of the host-cell receptor
A. Fusion of the viral envelope with a cellular membrane
A drug prevents the disassembly of a newly internalized viral capsid. Which stage of viral replication is directly inhibited?
A. Attachment
B. Genome replication
C. Uncoating
D. Virion release
C. Uncoating — Uncoating removes or disassembles the capsid so that the viral genome becomes accessible.
After uncoating, the genome of a typical DNA virus must usually be transported to which cellular location?
______
Nucleus
After entering a host cell, the genome of most RNA viruses must be delivered to which cellular location?
_______— Most RNA viruses carry out _______ and _______ replication here
Cytoplasm — Most RNA viruses carry out transcription and genome replication in the cytoplasm.
Once a viral genome reaches the correct cellular compartment, which set of processes must it direct?
A. Viral mRNA synthesis, viral protein synthesis, and genome replication
B. Host chromosome duplication, mitosis, and cytokinesis
C. Antibody synthesis, complement activation, and phagocytosis
D. Peptidoglycan synthesis, binary fission, and sporulation
A. Viral mRNA synthesis, viral protein synthesis, and genome replication — The virus must produce its proteins and generate new copies of its genome.
A newly expressed viral protein binds nucleic acid and functions as a virus-encoded polymerase. This protein was most likely produced from which type of viral gene?
A. Capsid gene
B. Envelope gene
C. Early gene
D. Late structural gene
C. Early gene — Early genes commonly encode nonstructural proteins, including DNA-binding proteins and viral enzymes.
A viral gene is expressed primarily after genome replication and produces a protein needed in thousands of copies to construct new virions. What type of gene is this?
A. Regulatory host gene
B. Late viral gene
C. Early viral gene
D. Cellular housekeeping gene
B. Late viral gene — Late genes generally encode structural and packaging proteins needed for viral assembly.
Where does transcription of the genome of most DNA viruses occur, and what machinery is generally used?
In the _______ using host-cell polymerases and enzymes
nucleus
A large DNA virus carries out its transcription in the cytoplasm rather than the nucleus. Which virus family is the classic exception to the usual DNA-virus rule?
______
Poxviruses
What is the primary function of a DNA-dependent DNA polymerase during viral replication?
A. Synthesize RNA from an RNA template
B. Synthesize protein from viral mRNA
C. Synthesize RNA from a DNA template
D. Synthesize DNA from a DNA template
D. Synthesize DNA from a DNA template — DNA-dependent DNA polymerase copies a DNA genome using DNA as the template.
Which factors can most directly limit the replication of a DNA virus within a host cell?
A. Availability of bacterial ribosomes and folate
B. Availability of RNA-dependent RNA polymerase and uracil
C. Availability of DNA polymerase and deoxyribonucleotides
D. Availability of peptidoglycan and transpeptidase
C. Availability of DNA polymerase and deoxyribonucleotides — DNA replication requires both an appropriate polymerase and deoxyribonucleotide substrates.
A very small DNA virus infects erythroid precursor cells but cannot efficiently replicate in mature, nondividing cells. Which virus group has this characteristic?
______
Parvoviruses
When a virus multiplies inside a human cell, it creates a strange genetic structure that our immune system easily spots because healthy human cells don't make it. What is this structure?
A. Single-stranded human DNA
B. Circular bacterial DNA
C.
Double-stranded human DNA
D. Double-stranded RNA
D. Double-stranded RNA
Human cells typically use ______-stranded RNA, so ______-stranded RNA acts like a massive red flag for our immune system
single
double
What family do lymphocytic choriomeningitis virus and the virus causing Lassa fever encephalitis belong to?
______
Arenavirus
What virus is a part of the rhabdovirus family?
_____
rabies
What family of viruses is the middle eastern respiratory syndrome (MERS) a part of?
_____
coronavirus
What major virus is a part of the orthomyxovirus family?
______ virus
influenza
All ______ viruses are icosahedral and replicate in the nucleus except poxvirus
DNA
Viruses have no _____ activity
metabolic
reovirus is ______ stranded and has a double ______
stranded
caspid
What RNA viruses are segmented? (4)
BOAR
1. Bunyavirus
2. Orthomyxovirus
3. Arenavirus
4. Reovirus
What RNA viruses are circular? (3)
BAD
1. Bunyavirus
2. Arenavirus
3. Delta virus
1. What is the largest DNA virus? _____
2. What is the smallest DNA virus? _____
Poxvirus
Parvovirus
If you inject pure genetic material (RNA) from a naked positive-sense RNA virus straight into a healthy cell, the cell starts making whole new viruses. Why does this happen?
A. The RNA must first be copied into DNA
B. The RNA genome is infectious by itself
C. The RNA is already packaged with host ribosomes
D. The RNA can replicate without producing proteins
B. The RNA genome is infectious by itself — A naked positive-sense RNA genome can initiate infection when introduced into a susceptible cell.
Why can the genome of a positive-sense RNA virus immediately initiate viral protein synthesis after entering the cytoplasm?
A. It contains a DNA-dependent polymerase
B. It first integrates into a host chromosome
C. It is converted into double-stranded DNA
D. It can function directly as messenger RNA
D. It can function directly as messenger RNA — Positive-sense RNA can bind host ribosomes and be translated.
Purified RNA from a negative-sense RNA virus is introduced into a susceptible cell but fails to initiate infection. What best explains this result?
A. Negative-sense RNA cannot be translated directly by ribosomes
B. Negative-sense RNA is immediately converted into host DNA
C. Negative-sense RNA cannot enter the cytoplasm
D. Negative-sense RNA lacks nucleotide bases
A. Negative-sense RNA cannot be translated directly by ribosomes — It must first be transcribed into positive-sense mRNA.
Which enzyme must a negative-sense RNA virus carry inside the virion to begin producing viral mRNA?
A. DNA-dependent DNA polymerase
B. Host-cell RNA polymerase II
C. RNA-dependent RNA polymerase
D. Reverse transcriptase
C. RNA-dependent RNA polymerase — Host cells cannot produce RNA from a negative-sense RNA template.
Where is the RNA-dependent RNA polymerase of a negative-sense RNA virus typically located when the virus enters a host cell?
A. Bound to the host-cell membrane
B. Free within the viral envelope
C. Associated with the genome in the nucleocapsid
D. Integrated into the host chromosome
C. Associated with the genome in the nucleocapsid — The polymerase must enter the cell along with the viral genome.
Influenza is unusual among most RNA viruses because an important portion of its replication occurs in which cellular location?
A. Nucleus
B. Lysosome
C. Golgi apparatus
D. Rough endoplasmic reticulum
A. Nucleus — Influenza is a negative-sense RNA virus that carries out transcription and genome replication in the nucleus.
Which combination is normally packaged within a retrovirus particle?
A. One DNA genome, one ribosome, and integrase
B. One RNA genome, two ribosomes, and a helicase
C. Two DNA genomes, two tRNAs, and a transcriptase
D. Two RNA genome copies, two tRNAs, and reverse transcriptase
D. Two RNA genome copies, two tRNAs, and reverse transcriptase
A viral mutant is missing a segment of its genome and can no longer produce the protein encoded by that segment. What type of mutant is this?
A. Plaque mutant
B. Deletion mutant
C. Host-range mutant
D. Conditional mutant
B. Deletion mutant — A deletion mutant has lost a portion of the genome and the function encoded by it.
A viral strain forms unusually small, cloudy areas of cell destruction in culture compared with the wild-type virus. How should this mutant be classified?
A. Attenuated mutant
B. Host-range mutant
C. Conditional mutant
D. Plaque mutant
D. Plaque mutant — Plaque mutants differ from the wild type in plaque size or appearance.
A mutant virus can infect human epithelial cells but can no longer infect the animal cells normally used for propagation. Which property has changed?
A. Plaque morphology
B. Host range
C. Genome polarity
D. Virion symmetry
B. Host range — Host-range mutants differ in the species or tissue types they can infect.
A viral mutant replicates in the host but produces much less severe disease than the wild-type strain. What type of mutant is it?
A. Reassortant mutant
B. Deletion mutant
C. Attenuated mutant
D. Plaque mutant
C. Attenuated mutant — Attenuated viruses have reduced virulence and cause less serious disease.
A viral mutant produces progeny at one temperature but fails to produce progeny at another because an essential protein becomes nonfunctional. What type of mutant is this?
A. Conditional mutant
B. Host-range mutant
C. Plaque mutant
D. Recombinant mutant
A. Conditional mutant — A conditional mutant replicates only under permissive conditions.
A temperature-sensitive viral mutant grows normally at 33°C but fails to produce virus at 39°C. What most likely occurs at 39°C?
A. The viral receptor disappears
B. The viral genome becomes positive sense
C. The host ribosomes stop functioning
D. A mutated essential viral protein becomes inactive
D. A mutated essential viral protein becomes inactive — The higher restrictive temperature alters the function or stability of the mutant protein.
Which types of viral mutants are commonly useful in the production of live viral vaccines?
A. Conditional, host-range, or attenuated mutants
B. Virulent, plaque-forming, or lethal mutants
C. Reassortant, oncogenic, or latent mutants
D. Wild-type, deletion, or recombinant mutants
A. Conditional, host-range, or attenuated mutants — These mutations can restrict replication or reduce disease while retaining immunogenicity.
Two viral genomes exchange corresponding portions of genetic material, producing a hybrid genome. What process has occurred?
A. Complementation
B. Reassortment
C. Marker rescue
D. Recombination
D. Recombination — Recombination exchanges genetic material between nucleic acid molecules or genomes.
Genetic recombination occurs particularly readily between which viral group?
A. Unrelated negative-sense RNA viruses
B. Related segmented RNA viruses
C. Related DNA viruses
D. Viroids and prions
C. Related DNA viruses — Homologous regions in related DNA viruses can undergo recombination readily.
Integration of retroviral DNA into host chromatin can be regarded as which type of genetic event?
A. Complementation
B. Marker rescue
C. Reassortment
D. Recombination
D. Recombination — Viral DNA becomes joined to host-cell DNA during integration.
A cell is simultaneously infected with two related viruses, and a progeny virus receives genetic material from both parental strains. What has been produced?
A. A defective interfering particle
B. A recombinant hybrid strain
C. A bacterial plasmid
D. A noninfectious capsid
B. A recombinant hybrid strain — Coinfection permits related viruses to exchange genetic material.
Coinfection of a cell with HSV-1 and HSV-2 can generate which product?
A. An intertypic recombinant herpesvirus
B. A segmented influenza virus
C. A defective prion particle
D. A bacteriophage lysogen
A. An intertypic recombinant herpesvirus — The progeny virus can contain genetic material from both HSV types.
Two different flu viruses infect the exact same cell, and the new baby viruses swap whole genetic pieces (RNA segments) with each other. What is this process called?
A. Reassortment
B. Recombination
C. Complementation
D. Marker rescue
A. Reassortment — Reassortment involves exchange of entire genome segments.
Which viruses are capable of undergoing reassortment?
Viruses with _____ genomes
segmented
Which pair contains viruses capable of reassortment?
_____ and _____
Influenza and reoviruses
When two completely different flu viruses swap genetic pieces, it can cause a massive, sudden change in the virus's surface proteins. What is this major change called?
A. Antigenic drift
B. Antigenic shift
C. Latent infection
D. Plaque transformation
B. Antigenic shift
Recombination exchanges _____ of genetic material, whereas reassortment exchanges _____ genome segments.
portions
entire
A broken virus can only multiply if a second, working virus is in the same cell to give it the missing protein it needs. What is this interaction called?
A. Complementation
B. Recombination
C. Reassortment
D. Antigenic shift
A. Complementation
A disabled infectious single-cycle HSV vaccine lacks an essential viral gene. How can this virus be produced in the laboratory?
A. Grow it at a restrictive temperature
B. Grow it in a cell line that expresses the missing gene product
C. Coinfect cells with influenza virus
D. Remove the viral capsid before infection
B. Grow it in a cell line that expresses the missing gene product
A deadly, broken virus becomes healthy and alive again after scientists inject a specific piece of normal, healthy DNA to replace the missing genetic information. What is this process called?
A. Complementation
B. Reassortment
C. Marker rescue
D. Antigenic shift
C. Marker rescue — A defined genetic sequence rescues a lethal or conditional-lethal mutation.
Which laboratory material could be used to perform marker rescue of a viral mutant?
A restriction _____ DNA fragment containing the normal sequence
endonuclease
What is an important experimental use of marker rescue in herpes simplex virus research?
A. Measuring plaque size
B. Producing antigenic shift
C. Determining the host-cell receptor
D. Mapping mutations within the viral genome
D. Mapping mutations within the viral genome — The rescuing DNA fragment identifies the region containing the defective gene.
What is transcapsidation?
A. Exchange of genome segments
B. A virus has the proteins of one strain but the genome of another
C. Repair of a defective viral gene
D. Integration into host DNA
B. A virus has the proteins of one strain but the genome of another — Transcapsidation produces phenotypically mixed viruses.
A virus has the capsid proteins of strain A but the genome of strain B. What has occurred?
A. Reassortment
B. Complementation
C. Recombination
D. Transcapsidation
D. Transcapsidation — The outside proteins and inside genome come from different viral strains.
What is usually required for transcapsidation to occur?
A. Coinfection of one cell by different viruses
B. Integration into the host genome
C. Infection at a low temperature
D. Loss of part of the viral genome
A. Coinfection of one cell by different viruses — The viruses must be present in the same cell for their components to mix.
Where are viral pseudotypes most commonly produced?
A. In normal human infections
B. In laboratories
C. Only in insects
D. Only in bacteria
B. In laboratories — Pseudotypes are uncommon outside experimental settings.
Repeatedly growing a virus under mild laboratory conditions may select for what type of strain?
A. More virulent strain
B. Segmented strain
C. Attenuated strain
D. Latent strain
C. Attenuated strain — Laboratory growth can select viruses that grow well in culture but cause less disease.
What is the main purpose of a viral vector?
A. To deliver a foreign gene into a target cell
B. To destroy viral RNA
C. To exchange viral genome segments
D. To produce antibodies
A. To deliver a foreign gene into a target cell — Viral vectors use the natural ability of viruses to enter cells.
Viral vectors may be used for which purposes?
A. Only bacterial identification
B. Gene replacement, vaccines, and cancer therapy
C. Only antibiotic delivery
D. Only measuring viral plaques
B. Gene replacement, vaccines, and cancer therapy — Viral vectors can deliver therapeutic or immune-stimulating genes.
Viral vectors are usually made from which viruses?
A. Fully virulent viruses
B. Bacterial viruses only
C. Wild-type viruses that spread normally
D. Defective or attenuated viruses
D. Defective or attenuated viruses — These are safer because they cannot spread normally or cause severe disease.
How are defective viral vectors produced in the laboratory?
A. They are grown without host cells
B. They are mixed with antibodies
C. They are grown in complementing cell lines
D. They are exposed to high temperatures
C. They are grown in complementing cell lines
Which viral vector commonly integrates its genetic material into the host genome?
A. Adenovirus
B. Retrovirus
C. Herpes simplex virus
D. Poxvirus
B. Retrovirus — Retroviral vectors insert a DNA copy of their genome into host DNA.
Which viral vectors generally deliver genes without integrating them into the host genome?
A. Adenovirus and herpes simplex virus
B. Retrovirus and lentivirus
C. Influenza virus and reovirus
D. Parvovirus and retrovirus
A. Adenovirus and herpes simplex virus — These vectors generally deliver genes without permanent genome integration.
Why are viruses classified as obligate intracellular parasites? A. They divide through binary fission B. They grow on artificial media C. They require host biochemical machinery D. They contain independent ribosomes
C. They require host biochemical machinery
How do viruses produce new infectious particles? A. By assembling individual components B. By dividing into daughter cells C. By undergoing mitotic division D. By forming bacterial endospores
A. By assembling individual components
Which process is not used for viral reproduction? A. Genome replication B. Protein synthesis C. Virion assembly D. Binary fission
D. Binary fission
What does the name picornavirus mean? A. Large DNA virus B. Small RNA virus C. Mantled RNA virus D. Respiratory orphan virus
B. Small RNA virus
What does the name togavirus indicate? A. Small naked virus B. Mantled enveloped virus C. Enteric orphan virus D. Adenoid-associated virus
B. Mantled enveloped virus
What does the original name reovirus represent? A. Replicating enveloped orphan B. Retroviral enteric organism C. Respiratory enveloped organism D. Respiratory, enteric, orphan
D. Respiratory, enteric, orphan
Why were adenoviruses and reoviruses originally named? A. Their initial isolation sites B. Their nucleic acid types C. Their capsid symmetries D. Their replication enzymes
A. Their initial isolation sites
What forms when viral proteins associate with genomes? A. Viral envelope B. Host ribosome C. Nucleocapsid D. Cellular membrane
C. Nucleocapsid
Helical nucleocapsids usually occur in which viruses? A. Naked positive-strand RNA viruses B. Naked double-stranded DNA viruses C. Enveloped DNA viruses D. Enveloped negative-strand RNA viruses
D. Enveloped negative-strand RNA viruses
What is delivered into cells with viral genomes? A. Neutralizing antibodies B. Nucleocapsid proteins C. Host-cell receptors D. Envelope lipids
B. Nucleocapsid proteins
Genome-bound nucleocapsid proteins may supply what? A. Viral replication enzymes B. Host-cell ribosomes C. Cellular attachment receptors D. Antiviral antibodies
A. Viral replication enzymes
Which processes are supported by carried viral enzymes? A. Translation and glycosylation B. Attachment and penetration C. Transcription and replication D. Assembly and release
C. Transcription and replication
Where may viral attachment proteins be located? A. Viral genome interior B. Capsid or envelope surface C. Host-cell nucleus D. Nucleocapsid core
B. Capsid or envelope surface
What is the primary function of a VAP? A. Cleave viral proteins B. Replicate viral genomes C. Bind target-cell receptors D. Assemble viral capsids
C. Bind target-cell receptors
What results from disrupting the virion’s outer package? A. Faster genome replication B. Increased receptor binding C. Enhanced viral uncoating D. Viral inactivation
D. Viral inactivation
How do antibodies against VAPs prevent infection? A. They block viral attachment B. They enhance viral assembly C. They activate viral polymerases D. They stabilize the envelope
A. They block viral attachment
Naked capsid viruses commonly use which route? A. Blood-borne transmission B. Respiratory droplet transmission C. Fecal-oral transmission D. Tissue transplantation
C. Fecal-oral transmission
Enveloped viruses commonly spread through which materials? A. Fluids and respiratory droplets B. Dry soil and dust C. Food and drinking water D. Environmental fungal spores
A. Fluids and respiratory droplets
Which routes also transmit many enveloped viruses? A. Feces and contaminated water B. Blood and tissue C. Dry surfaces and soil D. Food and arthropod eggs
B. Blood and tissue
What gives naked viruses environmental stability? A. Genome-associated enzymes B. Lipid surface membranes C. Flexible glycoprotein spikes D. Rigid protein capsids
D. Rigid protein capsids
A rigid capsid helps viruses withstand what? A. Harsh environmental conditions B. Host-cell transcription C. Antibody synthesis D. Viral genome integration
A. Harsh environmental conditions
Why are enveloped viruses relatively fragile? A. They contain no proteins B. They lack attachment factors C. They contain no genomes D. They possess lipid membranes
D. They possess lipid membranes
Which environmental condition readily damages envelopes? A. Refrigeration B. Isotonic saline C. Drying D. Neutral pH
C. Drying
Which chemical condition can disrupt viral envelopes? A. Glucose exposure B. Acidic conditions C. Oxygen exposure D. Neutral buffers
B. Acidic conditions
Which agents readily destroy lipid envelopes? A. Cytokines and complement B. Sugars and amino acids C. Salts and buffers D. Detergents and ether
D. Detergents and ether
What constitutes the outermost virion layer? A. Genome or polymerase B. Ribosome or mitochondrion C. Capsid or envelope D. Nucleus or cytoplasm
C. Capsid or envelope
What does the virion outer layer package? A. Host-cell enzymes B. Viral genome C. Cellular ribosomes D. Antiviral antibodies
B. Viral genome
What does the outer virion layer provide? A. Protection during transmission B. Host-cell energy production C. Antibody class switching D. Independent protein synthesis
A. Protection during transmission
The virion outer layer helps deliver virus where? A. Host-cell ribosomes B. Bacterial colonies C. Target cells D. Bone marrow stem cells
C. Target cells
Within an infected host, the outer layer assists what? A. Host-cell mitosis B. Spread toward target cells C. Bacterial transformation D. Antibody production
B. Spread toward target cells
What additional materials may virions contain? A. Essential or accessory proteins B. Functional host ribosomes C. Complete host chromosomes D. Independent mitochondria
A. Essential or accessory proteins
Why may virions carry specialized enzymes? A. To perform binary fission B. To generate host antibodies C. To synthesize cellular ATP D. To initiate cellular replication
D. To initiate cellular replication
The simplest viral structures share which property? A. They are multicellular B. They are symmetric C. They contain organelles D. They reproduce independently
B. They are symmetric
Which is a basic symmetric viral architecture? A. Helical structure B. Rectangular structure C. Cuboidal structure D. Branched structure
A. Helical structure
Which is another symmetric viral architecture? A. Filamentous colony B. Circular membrane C. Spiral bacterium D. Icosahedral structure
D. Icosahedral structure
Which pair represents basic viral symmetries? A. Circular and cuboidal B. Filamentous and rectangular C. Helical and icosahedral D. Branched and spherical
C. Helical and icosahedral
Where are helical nucleocapsids usually found in negative-strand RNA viruses? A. Outside naked capsids B. Within viral envelopes C. Inside host ribosomes D. Within bacterial membranes
B. Within viral envelopes
Human viruses with helical nucleocapsids generally possess what? A. Double-stranded DNA B. Icosahedral capsids C. Lipid envelopes D. Bacterial cell walls
C. Lipid envelopes
What structures form spikes on enveloped viruses? A. Surface glycoproteins B. Capsid enzymes C. Genome-binding proteins D. Host ribosomes
A. Surface glycoproteins
What is the main function of viral glycoprotein spikes? A. Replicate viral genomes B. Assemble nucleocapsids C. Bind target cells D. Destroy host ribosomes
C. Bind target cells
Which structural feature is shared by negative-strand RNA viruses? A. Naked capsid B. Lipid envelope C. Double-stranded genome D. Icosahedral nucleocapsid
B. Lipid envelope
How do defective interfering particles suppress normal viruses? A. Destroy viral genomes B. Block host receptors C. Occupy replication machinery D. Produce neutralizing antibodies
C. Occupy replication machinery
What occurs during viral complementation? A. Missing function is temporarily supplied B. Defective genome becomes permanently repaired C. Viral RNA becomes host DNA D. Both viruses exchange complete genomes
A. Missing function is temporarily supplied
What happens to the defective genome after complementation? A. It becomes wild-type B. It remains genetically defective C. It integrates permanently D. It gains new mutations
B. It remains genetically defective
A replication-defective HSV vaccine can initially enter cells because it contains what? A. Borrowed required protein B. Corrected viral genome C. Host-cell chromosome D. Extra viral polymerase
A. Borrowed required protein
Why can progeny from a one-shot HSV vaccine not spread? A. They lack viral genomes B. They cannot leave nuclei C. They lack the borrowed protein D. They immediately lyse themselves
C. They lack the borrowed protein
Which statement best defines a pseudotype virus? A. Two complete viral genomes B. One genome, another virus’s protein C. A permanently corrected mutant D. A virus lacking all proteins
B. One genome, another virus’s protein
In a pseudotype, which component determines inherited viral information? A. Borrowed surface protein B. Host-cell membrane C. Viral genome D. Neutralizing antibody
C. Viral genome