29 Questions
Which cellular process is activated by engaging apoptotic receptors?
Apoptosis
What is the primary focus of virology according to the text?
Cell biology
How do non-enveloped and enveloped viruses enter cells?
Endocytosis
What is critical for uncoating or disassembling viruses within cells?
$pH$ transitions
Where does viral replication and assembly primarily occur?
$Cytosol$
How do viruses achieve exit from the endosome into the cytosol?
Through multiple mechanisms
What mechanism do viruses use to mimic apoptotic fragments for efficient uptake?
$Cloaking$ mechanism
Which transcriptional targets inhibit host cell receptors receiving pro-inflammatory signals from neighbouring cells?
Targets within innate immune pathways
What are some transcriptional targets that are secreted factors for neighbouring cells?
Anti-inflammatory factors
Which class of viral fusion proteins can be activated upon docking to cell surface receptors or require pH transitions to become activated?
Class I, II, and III
Where does viral genome replication typically occur for RNA viruses?
Cytosol
How does the egress from the nucleus of enveloped viruses occur?
Distinct mechanisms
Where does Herpesvirus bud into?
Perinuclear space
What is the target of the vaccine for SARS-CoV-2?
Spike protein
Which entry pathways for SARS-CoV-2 require ACE2 receptor binding?
Endosomal entry and cell surface entry
What is required for S2 essential for viral fusion in SARS-CoV-2?
Cleavage event
How does influenza virus infection involve viral glycoproteins?
Attaching to host epithelial cells
What is a characteristic of rotavirus, a non-enveloped virus?
Causes acute gastroenteritis
How does rotavirus enter cells?
Through clathrin and non-clathrin mediated endocytosis
What explains viral protein interaction with the endosomal membrane during viral escape?
"Carpet model" and "pore formation" model
What was identified as major determinants of rotavirus infection, linking the viral life cycle with host cell biological processes?
AMPK and vacuolar ATP synthase
How does picornavirus RNA exit the capsid?
Through a pore, driven by a pH change and dissociation of viral proteins
What do over 75,000 viral genomes code for?
2 to 2000 proteins
Which type of life cycle do NOT ALL bacteriophages go into?
Lytic pathway
What results from the integration of a phage genome into the bacterial genome?
Reproduction of phages and lysis of the cell host
What do bacteriophages inject through the bacterial wall?
DNA
What resulted in the identification of the Crispr-Cas9 gene editing system?
Bacterial anti-viral immune system
What makes phage therapy very promising as an antibacterial treatment?
High specificity and adaptability
What can phages re-evolve to overcome bacterial anti-viral strategies?
Enzymes to degrade coats or modifications
Study Notes
Viral Life Cycle and Host Interaction
- Phages are abundant and do not disturb the microbiome, making them a potential alternative to antibiotics
- Phages can self-replicate and lyse cells, making phage therapy an efficient system to improve antibiotic potency
- Over 75,000 viral genomes have been sequenced, coding for 2 to 2000 proteins
- Influenza virus infection involves viral glycoproteins attaching to host epithelial cells, followed by viral RNA and protein assembly into new virions
- Animal viruses can be enveloped or non-enveloped, with different characteristics and entry mechanisms
- Rotavirus, a non-enveloped virus, causes acute gastroenteritis and led to the death of ~453,000 children under 5 in 2008
- Rotavirus enters cells through clathrin and non-clathrin mediated endocytosis, requiring specific cellular factors for viral exit from the endosome
- Viral exit from the endosome generally relies on pH transitions, which can open helical proteins in capsid proteins or activate viral proteases
- The "carpet model" and "pore formation" model explain viral protein interaction with the endosomal membrane during viral escape
- Picornavirus RNA exits the capsid through a pore, driven by a pH change and dissociation of viral proteins
- A genome-wide siRNA screen identified host genes that either increased or decreased rotavirus infection, linking the viral life cycle with host cell biological processes
- AMPK and vacuolar ATP synthase were identified as major determinants of rotavirus infection, with links to endosomal acidification and mTOR signaling.
Test your knowledge on viral life cycles, host interactions, and the potential of phage therapy as an alternative to antibiotics. Explore the mechanisms of viral entry, replication, and escape from host cells, and the impact of viral infections on public health.
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