Virus entry attatchment Flashcards
Examples of virus attatchment factors:
Glycoaminoglycans
Linear polysaccharides
Linked or unliked cell surface proteins. often negatively charged
Is Human rhinovirus enveloped or non enveloped?
Non enveloped
What is the receptor for HRV14/16 (major)?
ICAM-1
What is the receptor for HRV2 (minor)?
Low density lipoprotein receptor (LDLR)
What is the normal function of ICAM-1
Intracellular adhesion
What is the normal function of LDLR?
Uptake of lipids
Where is the picornavirus receptor binding site?
Base of canyon
What is at the base of the canyon?
A pocket occupied by a pocket factor, a lipid.
Primary receptor of HIV
CD4
What is the normal function of CD4?
Binding tp Class II MHC on APC, also binds IL16.
What chemokine receptors does HIV also bind to?
CCR5 and CxCR4
What gps multimerise to form spikes on HIV?
Gp41 and gp120 –> trimers.
What loop is there on the gp120 HIV protein?
V3 loop
What does V3 loop bind to prior to CD4/CCR5?
GAGs
Timeline of cell tropism in HIV
Early HIV infection in macrophages expressing CCR5
V3 loop mutation, acidic to basic amino acids
Later, HIV infects T-cells expressing CxCR4.
What drug is a CCR5 antagonist?
Maraviroc
Is influenza A, enveloped?
Yes
What are the two influenza A surface glycoproteins
Hemagglutinin (HA)
Neuraminidase (NA)
What determined flu host range?
Sialic acid linkage
What does avain HA sialic acid bind to
2,3-linkage to galactose
What does human HA sialic acid bind to
2,6-linkage to galactose
What is the trimer glycoprotein of SARS-CoV-2?
Spike glycoprotein S.
Is SARS-CoV-2 enveloped?
Yes
What is S cleaved into (covid)
S1 and S2
What does S1 contain (covid)
Receptor binding domain
What is the SARS-CoV-2 primary receptor?
Angiotensin converting enzyme 2 (ACE-2)
Normal function of ACE-2
Cleaves angiotensin into Ang1-9, role in blood pressure and inflammation
What is the additional receptor of SARS-CoV-2?
Transmembrane protease serine 2 (TMPRSS2)
What does TMPRSS2 do to S?
Cleaves into S1 and S2
What is TMPRSS2 cleavage of S dependent on?
pH.
How does clathrin mediated endocytosis work?
Clathrin cage causes membrane to curve. Pinches off to form vesicle, targeted to endosome.
How does non clathrin dependent endocytosis work?
Caveolae form from cholesterol rich lipid rafts. Targeted to ER/late endosomes
What viruses use non clathrin dependent endocytosis
Polyomaviruses and bunyaviruses
How does macropintoctosis work?
Membrane ruffling large vesicles, targeted to late endosome
What viruses use macopinoctosis?
Large viruses e.g herpes, pox and ebola
What is phagocytosis activity based on?
Actin and surface receptors
What type of endocytosis occurs in macrophages?
Phagocytosis
What type of endocyotsis does the mimivirus use?
Endocytosis
How do enveloped viruses penetrate?
Receptor binding
Endocytosis
Endosome under acidic pH
Fusion of biral and endosomal membranes lead to release of capsid into cytoplasm
What drives the conformational change in the influenza virus HA.
Low pH
How does HIV penentrate?
Receptor binding
Fusion of viral and plasma membranes cause release of capsid into cytoplasm
Where are fusion peptides found?
In viral glycoproteins
What is a fusion peptide
Short hydrophobic amino acid sequences that are able to fuse the viral and cellular membranes.
Penetration of non-enveloped virus (1)
Receptor binding
Endocytosis
Held in an endosome, acidic pH
Three options: Uncoating before or after endosome distruption or pore formation
Penetration of poliovirus (acid stable)
Receptor binds, memnbrane disruption and uncoating and pore formation
