Podcast
Questions and Answers
What is the purpose of staining cells in the plaque assay?
What is the purpose of staining cells in the plaque assay?
- To enhance the growth of viruses
- To visualize plaques, which appear clear (correct)
- To isolate and store red blood cells
- To measure the number of bacteria
Why are dilutions done in virus counting?
Why are dilutions done in virus counting?
- To increase the size of plaques
- To enhance the infectivity of the viruses
- To prevent bacterial growth
- To make it easier to count the number of viruses (correct)
What is the result of excess virus binding with red blood cells in a hemagglutination assay?
What is the result of excess virus binding with red blood cells in a hemagglutination assay?
- Clearing of red blood cells
- Lysis of red blood cells
- Agglutination (clumping) of red blood cells (correct)
- Increased solubility of red blood cells
What causes a clearing of the bacterial culture in the presence of bacteriophages?
What causes a clearing of the bacterial culture in the presence of bacteriophages?
What method is used to visualize virus particles?
What method is used to visualize virus particles?
How are virus replication cycles studied?
How are virus replication cycles studied?
What is the initial drop in infectious titer attributed to?
What is the initial drop in infectious titer attributed to?
How are viruses classified based on the system developed by David Baltimore?
How are viruses classified based on the system developed by David Baltimore?
What are capsids composed of?
What are capsids composed of?
What defines the symmetry of helical capsids?
What defines the symmetry of helical capsids?
What type of symmetry do identical subunits in capsids have?
What type of symmetry do identical subunits in capsids have?
What is used to study detailed pathways of virus replication?
What is used to study detailed pathways of virus replication?
What is the method for ensuring each cell receives at least one infectious particle during virus replication cycle studies?
What is the method for ensuring each cell receives at least one infectious particle during virus replication cycle studies?
What is the basis for the classification of viruses into seven groups by David Baltimore's system?
What is the basis for the classification of viruses into seven groups by David Baltimore's system?
What is the role of identical subunits in capsids?
What is the role of identical subunits in capsids?
What is the method for visualizing virus particles as light images against a dark background?
What is the method for visualizing virus particles as light images against a dark background?
What is the basis for grouping virus species into genera?
What is the basis for grouping virus species into genera?
How are virus families grouped according to the International Committee on Taxonomy of Viruses (ICTV)?
How are virus families grouped according to the International Committee on Taxonomy of Viruses (ICTV)?
What distinguishes most viruses with dsDNA genomes?
What distinguishes most viruses with dsDNA genomes?
What is a characteristic of viruses with reverse transcriptase (RT) in their replication cycle?
What is a characteristic of viruses with reverse transcriptase (RT) in their replication cycle?
What is a distinguishing feature of 'Â' RNA viruses that infect vertebrates?
What is a distinguishing feature of 'Â' RNA viruses that infect vertebrates?
What is a characteristic of dsRNA viruses that contributes to their broad host range?
What is a characteristic of dsRNA viruses that contributes to their broad host range?
What is a distinguishing feature of satellite viruses?
What is a distinguishing feature of satellite viruses?
How do satellite nucleic acids replicate in the presence of a helper virus?
How do satellite nucleic acids replicate in the presence of a helper virus?
What distinguishes viroids from other viruses?
What distinguishes viroids from other viruses?
What is a unique characteristic of dsRNA viruses' mechanism of transcription?
What is a unique characteristic of dsRNA viruses' mechanism of transcription?
What is the process of developing viral envelopes at the cell membrane called?
What is the process of developing viral envelopes at the cell membrane called?
What reflects the composition of the membrane from which the viral lipid bilayer was derived?
What reflects the composition of the membrane from which the viral lipid bilayer was derived?
Where can viral glycoproteins be inserted during the budding process?
Where can viral glycoproteins be inserted during the budding process?
What interacts directly with cytoplasmic tails of envelope proteins during budding?
What interacts directly with cytoplasmic tails of envelope proteins during budding?
What do some viruses use to interact with both viral spikes and nucleocapsids during budding?
What do some viruses use to interact with both viral spikes and nucleocapsids during budding?
What is inserted into the lipid membrane to form the viral envelope?
What is inserted into the lipid membrane to form the viral envelope?
What is the nature of viral envelopes in terms of symmetry?
What is the nature of viral envelopes in terms of symmetry?
Aside from lipid analyses, what other method can be used to determine where a virus budded from?
Aside from lipid analyses, what other method can be used to determine where a virus budded from?
What is the process of developing viral envelopes at internal membranes called?
What is the process of developing viral envelopes at internal membranes called?
What is wrapped in a membrane into which viral glycoproteins have been inserted?
What is wrapped in a membrane into which viral glycoproteins have been inserted?
Where are envelope proteins synthesized?
Where are envelope proteins synthesized?
What prevents dehydration of virus particles' external surfaces?
What prevents dehydration of virus particles' external surfaces?
What directs the specificity for incorporation of viral genomes into virions?
What directs the specificity for incorporation of viral genomes into virions?
What neutralizes the negative charges on DNA and condenses the viral DNA for optimal packaging?
What neutralizes the negative charges on DNA and condenses the viral DNA for optimal packaging?
What drives the formation of viral envelopes by budding?
What drives the formation of viral envelopes by budding?
What can some viruses generate during budding?
What can some viruses generate during budding?
How is the release of the viral genome from virions achieved?
How is the release of the viral genome from virions achieved?
What are virions energetically?
What are virions energetically?
What is virus classification based on?
What is virus classification based on?
What can capsid assembly depend on?
What can capsid assembly depend on?
What is the process of developing viral envelopes at the cell membrane called?
What is the process of developing viral envelopes at the cell membrane called?
What reflects the composition of the membrane from which the viral lipid bilayer was derived?
What reflects the composition of the membrane from which the viral lipid bilayer was derived?
Where are viral glycoproteins inserted during the budding process?
Where are viral glycoproteins inserted during the budding process?
What interacts directly with cytoplasmic tails of envelope proteins (viral spike) during budding?
What interacts directly with cytoplasmic tails of envelope proteins (viral spike) during budding?
What is the nature of viral envelopes in terms of symmetry?
What is the nature of viral envelopes in terms of symmetry?
What drives the formation of viral envelopes by budding?
What drives the formation of viral envelopes by budding?
What is a distinguishing feature of dsRNA viruses' mechanism of transcription?
What is a distinguishing feature of dsRNA viruses' mechanism of transcription?
What is the method for visualizing virus particles as light images against a dark background?
What is the method for visualizing virus particles as light images against a dark background?
What is the basis for grouping virus species into genera?
What is the basis for grouping virus species into genera?
What is wrapped in a membrane into which viral glycoproteins have been inserted?
What is wrapped in a membrane into which viral glycoproteins have been inserted?
What is a distinguishing feature of most 'Â' RNA genomes less than 10kb?
What is a distinguishing feature of most 'Â' RNA genomes less than 10kb?
What is a characteristic of dsRNA viruses that contributes to their broad host range?
What is a characteristic of dsRNA viruses that contributes to their broad host range?
What is a unique characteristic of dsRNA viruses' mechanism of transcription?
What is a unique characteristic of dsRNA viruses' mechanism of transcription?
What is a distinguishing feature of satellite viruses?
What is a distinguishing feature of satellite viruses?
What is the basis for grouping virus species into genera?
What is the basis for grouping virus species into genera?
What is a characteristic of viruses with reverse transcriptase (RT) in their replication cycle?
What is a characteristic of viruses with reverse transcriptase (RT) in their replication cycle?
What is a distinguishing feature of most viruses with dsDNA genomes?
What is a distinguishing feature of most viruses with dsDNA genomes?
What is a distinguishing feature of viroids?
What is a distinguishing feature of viroids?
What is a distinguishing feature of satellite nucleic acids?
What is a distinguishing feature of satellite nucleic acids?
What is a characteristic of viruses with ssDNA genomes?
What is a characteristic of viruses with ssDNA genomes?
Which organelle is involved in the glycosylation process of viral proteins?
Which organelle is involved in the glycosylation process of viral proteins?
What drives the formation of viral envelopes by budding?
What drives the formation of viral envelopes by budding?
What is the role of packaging signals in virion assembly?
What is the role of packaging signals in virion assembly?
What is the basis for virus classification according to David Baltimore's system?
What is the basis for virus classification according to David Baltimore's system?
What is the function of core proteins in viral assembly?
What is the function of core proteins in viral assembly?
What can some viruses generate during budding?
What can some viruses generate during budding?
What is the characteristic of virions in terms of stability?
What is the characteristic of virions in terms of stability?
What is the function of scaffolding proteins in capsid assembly?
What is the function of scaffolding proteins in capsid assembly?
What type of integral membrane proteins are involved in viral assembly?
What type of integral membrane proteins are involved in viral assembly?
Where are envelope proteins synthesized?
Where are envelope proteins synthesized?
What is the process of developing viral envelopes at the cell membrane called?
What is the process of developing viral envelopes at the cell membrane called?
Where can viral envelopes be derived from?
Where can viral envelopes be derived from?
What do some nucleocapsids interact directly with during budding?
What do some nucleocapsids interact directly with during budding?
What reflects the composition of the membrane from which the viral lipid bilayer was derived?
What reflects the composition of the membrane from which the viral lipid bilayer was derived?
Where are envelope glycoproteins synthesized?
Where are envelope glycoproteins synthesized?
What is the role of glycosylation in viral proteins?
What is the role of glycosylation in viral proteins?
What directs the specificity for incorporation of viral genomes into virions?
What directs the specificity for incorporation of viral genomes into virions?
What neutralizes the negative charges on viral DNA and condenses it for optimal packaging?
What neutralizes the negative charges on viral DNA and condenses it for optimal packaging?
What drives the formation of viral envelopes by budding?
What drives the formation of viral envelopes by budding?
What is the basis for virus classification?
What is the basis for virus classification?
What can some viruses generate during budding?
What can some viruses generate during budding?
What is the basis for grouping virus species into genera?
What is the basis for grouping virus species into genera?
What can cause the release of the viral genome?
What can cause the release of the viral genome?
What is a distinguishing feature of most viruses with dsDNA genomes?
What is a distinguishing feature of most viruses with dsDNA genomes?
What are virions energetically?
What are virions energetically?
What is a unique characteristic of dsRNA viruses' mechanism of transcription?
What is a unique characteristic of dsRNA viruses' mechanism of transcription?
What are the two types of integral membrane proteins involved in viral assembly?
What are the two types of integral membrane proteins involved in viral assembly?
What is a characteristic of viruses with reverse transcriptase (RT) in their replication cycle?
What is a characteristic of viruses with reverse transcriptase (RT) in their replication cycle?
What can depend on the size, shape, and complexity of the capsid in viral assembly?
What can depend on the size, shape, and complexity of the capsid in viral assembly?
What is a distinguishing feature of satellite nucleic acids?
What is a distinguishing feature of satellite nucleic acids?
Where does the glycosylation process of viral proteins occur?
Where does the glycosylation process of viral proteins occur?
What is a distinguishing feature of satellite viruses?
What is a distinguishing feature of satellite viruses?
What is a distinguishing feature of viroids?
What is a distinguishing feature of viroids?
What is a characteristic of viruses with ssDNA genomes?
What is a characteristic of viruses with ssDNA genomes?
What is a distinguishing feature of dsRNA viruses' mechanism of transcription?
What is a distinguishing feature of dsRNA viruses' mechanism of transcription?
What is a distinguishing feature of satellite nucleic acids' replication?
What is a distinguishing feature of satellite nucleic acids' replication?
What is a distinguishing feature of satellite viruses' replication?
What is a distinguishing feature of satellite viruses' replication?
What is a distinguishing feature of viroids' replication?
What is a distinguishing feature of viroids' replication?
Study Notes
Virus Replication and Structure Overview
- Not all virus particles are infectious, as disrupted or defective virions, empty capsids, and cellular anti-viral defenses can interfere with virus replication
- Electron microscopy is used to visualize virus particles, which appear as light images against a dark background due to negative staining
- Virus replication cycles are studied using the MOI (Multiplicity of Infection) by infecting 10^3-10^6 cells with an excess of virus to ensure each cell receives at least one infectious particle
- The initial drop in infectious titer is due to defective particles and uncoating inside the host cell
- Analysis of viral macromolecules can reveal detailed pathways of virus replication, which vary greatly depending on host cell, viral genome, and virus complexity
- Virus replication cycles involve attachment to a host cell, entry into the host cell, genome replication and gene expression, assembly and morphogenesis, and release/exit
- Viruses can be divided into seven groups based on the system developed by David Baltimore
- Virions have evolved structures to efficiently transmit RNA or DNA genomes, with a rigid, symmetrical capsid and enclosed viral genome
- Capsids are composed of many copies of identical subunits, providing genetic economy and self-assembly
- Identical subunits can have tetrahedral, cubic, or icosahedral symmetry, with helical nucleocapsids accommodating variable genome lengths
- Helical capsids' symmetry is defined by the number of subunits per turn and the displacement along the helical axis between subunits
- For negative strand RNA viruses, the genome winds along a groove that follows a helical path of protein subunits, with each protein subunit binding a fixed number of nucleotides
Viral Structure and Assembly Overview
- Envelope glycoproteins have a large glycosylated external domain, a hydrophobic transmembrane anchor domain, and a short internal tail.
- Envelope proteins are synthesized on ribosomes in the ER and inserted into the plasma membrane via standard export pathways for cell surface proteins.
- There are two types of integral membrane proteins, Type I and Type II, with different orientations and signal sequences for membrane insertion.
- The glycosylation process of viral proteins occurs in the ER/Golgi and prevents dehydration of virus particles' external surfaces.
- Capsid assembly can depend on the size, shape, and complexity of the capsid, and some viruses require scaffolding proteins for procapsid formation.
- Packaging signals direct the specificity for incorporation of viral genomes into virions by interacting with capsid proteins.
- Core proteins neutralize the negative charges on DNA and condense the viral DNA for optimal packaging, resembling chromatin.
- Interactions between viral proteins drive the formation of viral envelopes by budding, involving membrane curvature and different mechanisms.
- Budding can be driven by interactions between envelope glycoproteins, matrix, or nucleocapsids, and some viruses can generate empty envelopes during budding.
- The release of the viral genome can occur by proteolytic cleavage of capsid proteins, unspooling of the genome, or interaction with cytoplasmic components.
- Virions are energetically metastable and can easily dissociate with the right trigger, and assembly and disassembly are not a simple reversal of the processes.
- Virus classification is based on molecular architecture, genetic relatedness, and host organism, using criteria such as nucleic acid genome type, capsid symmetry, and presence of an envelope.
Viral Structure and Assembly Overview
- Envelope glycoproteins have a large glycosylated external domain, a hydrophobic transmembrane anchor domain, and a short internal tail.
- Envelope proteins are synthesized on ribosomes in the ER and inserted into the plasma membrane via standard export pathways for cell surface proteins.
- There are two types of integral membrane proteins, Type I and Type II, with different orientations and signal sequences for membrane insertion.
- The glycosylation process of viral proteins occurs in the ER/Golgi and prevents dehydration of virus particles' external surfaces.
- Capsid assembly can depend on the size, shape, and complexity of the capsid, and some viruses require scaffolding proteins for procapsid formation.
- Packaging signals direct the specificity for incorporation of viral genomes into virions by interacting with capsid proteins.
- Core proteins neutralize the negative charges on DNA and condense the viral DNA for optimal packaging, resembling chromatin.
- Interactions between viral proteins drive the formation of viral envelopes by budding, involving membrane curvature and different mechanisms.
- Budding can be driven by interactions between envelope glycoproteins, matrix, or nucleocapsids, and some viruses can generate empty envelopes during budding.
- The release of the viral genome can occur by proteolytic cleavage of capsid proteins, unspooling of the genome, or interaction with cytoplasmic components.
- Virions are energetically metastable and can easily dissociate with the right trigger, and assembly and disassembly are not a simple reversal of the processes.
- Virus classification is based on molecular architecture, genetic relatedness, and host organism, using criteria such as nucleic acid genome type, capsid symmetry, and presence of an envelope.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Description
Test your knowledge of virus replication and structure with this quiz. Explore topics such as electron microscopy, virus replication cycles, viral macromolecules, viral classification, and virion structures. Understand the intricate pathways of virus replication and the evolution of virions' structures to transmit RNA or DNA genomes efficiently.
