CMB1003/L13 Viral Transmission & Structure Flashcards
Briefly outline the 6 steps of virus multiplication.
Attachment
Penetration
Uncoating
Biosynthesis
Assembly
Release
Describe the attachment phase of virus multiplication using the example of HIV. (4)
Diffusion
Low affinity receptor - heparan sulphate - binding induces conformational change in gp120 to expose:
Primary receptor (CD4 or DC-SIGN on dendritic cells)
Coreceptor(s) - CCR5 or CXCR4
What is the function of ICAM-1 receptor and the virus that targets it?
Intracellular adhesion molecule
Rhinovirus
What is the function of Acetylcholine receptor and the virus that targets it?
Neuronal signal transducer
Rabies virus
What is the function of CDW150 (SLAM) receptor and the virus that targets it?
Lymphocyte activation
Measles virus
What is the function of Angiotensin-converting enzyme 2 (ACE2) receptor and the virus that targets it?
Maturation of angiotensin - vasoconstriction and blood pressure
SARS-CoV-2
What is the function of CCR5 receptor and the virus that targets it?
Chemokine receptor
HIV
Give 2 ways in which internalization of viruses occurs.
Fusion from without
Receptor mediated endocytosis
Give an example of a virus that fuses from without.
Pseudorabies virus
HIV
Give an example of a virus that uses receptor mediated endocytosis.
Influenza
Poliovirus
What enzyme do RNA viruses require?
Own RNA polymerases
(RNA-dependent RNA polymerase)
What is the function of the proteins encoded by the virus genome? (3)
Replication of genome
Packaging of genome into virus particles
Alter metabolism of infected cell
What is translation of most viral mRNAs dependent on?
5’ terminal cap
Why must viruses compete for host cell ribosomes?
They do not have their own ribosomes
What binds to the cap and 40S ribosomal subunit?
Eukaryotic initiation factors (eIFs)
How is protein synthesis inhibited in virally infected cells? (2)
Directly by virus
Action of interferon
What post-translational modifications do viral proteins undergo?
The same as the host cell proteins
How do enveloped viruses acquire a membrane and surface glycoproteins?
Budding through plasma membrane or nucleus
Give an example of a virus which is released by cell lysis.
Poliovirus
Give an example of a virus which is released by budding from plasma membrane, and into lumen of ER.
Membrane - Influenza
ER - Rotavirus
Give an example of a virus which is spread from cell to cell via pores, and inducing fusion of membranes.
Pores - herpesvirus
Fusion - RSV
What can precede or follow release of a virus?
A maturation step
What is viremia?
An increase in the concentration of the virus in your bloodstream or the lymphatic system
Describe the M13 filamentous bacteriophage. (4)
Circular ssDNA
Cloning and DNA-sequencing
Released without lysing host cell
‘Budding’
Why are bacteriophage important?
Can turn bacteria virulent
Alternative to antibiotics
Recombinant DNA technology
