Podcast
Questions and Answers
What drives the collision of virions and host cells during the initiation of infection?
What drives the collision of virions and host cells during the initiation of infection?
- Magnetic attraction
- Thermal expansion
- Chemical reactions
- Brownian motion (correct)
Which group of viruses includes Retroviruses such as HIV?
Which group of viruses includes Retroviruses such as HIV?
- ssRNA-RT viruses (correct)
- dsRNA viruses
- ssDNA viruses
- dsDNA viruses
What is one of the major steps in a virus finding the right host cell?
What is one of the major steps in a virus finding the right host cell?
- Using lytic enzymes
- Replicating its genetic material
- Entering the nucleus of the cell
- Adhering to the cell surface via electrostatic interaction (correct)
Which statement is true regarding the specificity of infection by viruses?
Which statement is true regarding the specificity of infection by viruses?
What is the role of receptor molecules on the surface of host cells in virus infection?
What is the role of receptor molecules on the surface of host cells in virus infection?
How are DNA viruses typically transcribed during their infection process?
How are DNA viruses typically transcribed during their infection process?
Which statement describes virions during the initial stages of infection?
Which statement describes virions during the initial stages of infection?
What type of interaction aids in the viruses’ collision with host cells?
What type of interaction aids in the viruses’ collision with host cells?
What is the role of TMPRSS2 and Cathepsin B/L in the process of viral infection?
What is the role of TMPRSS2 and Cathepsin B/L in the process of viral infection?
What occurs to the receptor binding domain (RBD) during infection?
What occurs to the receptor binding domain (RBD) during infection?
Which of the following statements is true regarding the fusion peptide?
Which of the following statements is true regarding the fusion peptide?
Why is the receptor binding domain (RBD) considered a target for neutralizing antibodies?
Why is the receptor binding domain (RBD) considered a target for neutralizing antibodies?
Which enzymes are primarily responsible for exposing the receptor binding domain (RBD)?
Which enzymes are primarily responsible for exposing the receptor binding domain (RBD)?
What is the role of high affinity receptors in viral infection?
What is the role of high affinity receptors in viral infection?
How do disruptions in receptor genes affect viral infections?
How do disruptions in receptor genes affect viral infections?
Which statement about accessory receptors is true?
Which statement about accessory receptors is true?
What happens when a cell fails to express the appropriate receptor for a virus?
What happens when a cell fails to express the appropriate receptor for a virus?
What is a key factor in the reason why some viruses infect specific cell types?
What is a key factor in the reason why some viruses infect specific cell types?
Why might avian influenza someday affect humans?
Why might avian influenza someday affect humans?
What is the function of neuraminidase in viral infections?
What is the function of neuraminidase in viral infections?
Which of the following best describes the role of receptor genes in viral infections?
Which of the following best describes the role of receptor genes in viral infections?
What role do fibrous stems play in the viral fusion process?
What role do fibrous stems play in the viral fusion process?
What occurs after the virus binds to the receptor on the target cell?
What occurs after the virus binds to the receptor on the target cell?
What triggers the conformational change in HA during the viral fusion of influenza virus?
What triggers the conformational change in HA during the viral fusion of influenza virus?
What is the purpose of pumping H+ ions into the endosome?
What is the purpose of pumping H+ ions into the endosome?
What happens to the viral and host cell membranes during fusion?
What happens to the viral and host cell membranes during fusion?
What occurs following the formation of an endosome during the viral entry process?
What occurs following the formation of an endosome during the viral entry process?
How are globular heads relevant to the viral fusion process?
How are globular heads relevant to the viral fusion process?
What is the primary outcome of the conformational change in HA during influenza viral fusion?
What is the primary outcome of the conformational change in HA during influenza viral fusion?
What is the primary effect of the endosome formation on the dengue virus?
What is the primary effect of the endosome formation on the dengue virus?
How does the dengue virus adapt during endosome formation?
How does the dengue virus adapt during endosome formation?
What occurs to the viral RNA after the capsid is released into the cytoplasm?
What occurs to the viral RNA after the capsid is released into the cytoplasm?
What characteristic does the viral RNA possess that allows it to be translated into proteins directly?
What characteristic does the viral RNA possess that allows it to be translated into proteins directly?
Which structure binds to initiate the translation of the viral RNA?
Which structure binds to initiate the translation of the viral RNA?
What is the result of the translation of the whole viral genome?
What is the result of the translation of the whole viral genome?
Where are the capsid proteins located after translation?
Where are the capsid proteins located after translation?
What differentiates the location of the envelope and membrane proteins from the capsid protein?
What differentiates the location of the envelope and membrane proteins from the capsid protein?
Study Notes
Initiation of Infection
- Viruses initiate infection by colliding with host cells, a process influenced by Brownian motion, diffusion laws, and electrostatic interactions.
- DNA viruses can be transcribed to RNA intermediates, which can then be reverse transcribed back to DNA.
Finding the Right Cell
- Viruses exhibit specificity of infection; not all cells can be targeted.
- Major steps for viruses to find the correct host cell:
- Adhere to cell surface through electrostatic interactions.
- Attach to specific receptor molecules once in proximity to the cell membrane; multiple receptors may be involved.
- Disruption of receptor gene blocks viral infection, explaining susceptibility variations across different cell types.
Replication Cycle of Viruses
- Viral attachment involves accessory receptors for low-affinity binding, which may facilitate penetration but are not essential for entry.
- High-affinity receptors are crucial for viral entry; cells lacking appropriate receptors cannot be infected.
Viral Fusion Mechanism
- Fusion peptide undergoes configuration changes when activated by TMPRSS2 and Cathepsin B/L proteases.
- The receptor-binding domain (RBD) configuration shifts, exposing the binding site, initiating viral infection through ACE2 enzyme interaction.
Viral Entry Process (Influenza Virus)
- Virus approaches a target cell and binds via the hemagglutinin (HA) to the receptor.
- Endocytosis occurs, leading to endosome formation and a decrease in pH, causing conformational changes in HA.
- Acidic endosome environment allows the viral capsid to release its genetic material into the cytoplasm.
Dengue Virus Infection
- Aedes aegypti mosquitoes are the primary carriers of the dengue virus.
- The viral RNA is a positive-sense strand that gets directly translated into proteins by the ribosomes in the rough endoplasmic reticulum.
- Viral genome is expressed as a polyprotein chain, which has to be processed into functional proteins.
Important Notes
- Receptor mutations can lead to new modes of infection, demonstrating the dynamic nature of viral adaptability (example: avian influenza).
- Configuration changes during fusion can promote the infectious process, indicating the importance of structural adaptations in viral success.
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Description
This quiz covers the process of viral invasion of host cells, focusing on the critical initial phase of infection. It discusses how viruses collide with host cells to initiate infection, highlighting the mechanisms involved in this stage. Understanding these concepts is essential for studying virology and infectious diseases.
