1) Which one of the following choices correctly identifies the nature of interac
ID: 274105 • Letter: 1
Question
1) Which one of the following choices correctly identifies the nature of interactions that occur between glycan attachment factors and viral proteins?
They are relatively nonspecific and electrostatic
They are generally specific and electrostatic
They are relatively nonspecific and hydrophobic
They are generally covalent and involve hydrogen bonds
They are generally specific and hydrophobic
2) Which one or more of the following statements is/are true about viral attachment factors and receptors? Note: points will be deducted for wrong answers.
Glycoproteins are the only components of viruses that can interact with attachment factors and receptors
Binding of attachment factors is usually irreversible, whereas receptor binding is usually reversible
Receptor binding is more specific than attachment factor binding
Receptor binding actively promotes viral penetration, whereas attachment factor binding does not
Some viruses bind to two or more cell surface receptors to initiate the viral entry process.
3) Most viruses gain entry into host cells via the endocytic pathway, which offers a virus several advantages. In the following list, identify those statements that represent advantages. Note: points will be deducted for wrong answers.
The virus can gain direct entry to the nucleus
The virus can move via endocytic vesicles deep into the cytoplasm
The virus can gain direct entry to the endoplasmic reticulum
The virus does not have to bind to a receptor or attachment factor
The virus can exploit molecular motors to move it to the nucleus
The virus uses the low pH of the endosome as a signal to activate penetration reactions that allow virus escape into the cytoplasm at specific locations or before the virus is delivered to the hydrolytic lysosomes.
No viral component remains on the cell surface after penetration for detection by the host’s immune defenses.
a.They are relatively nonspecific and electrostatic
b.They are generally specific and electrostatic
c.They are relatively nonspecific and hydrophobic
d.They are generally covalent and involve hydrogen bonds
e.They are generally specific and hydrophobic
Explanation / Answer
1 e. The glycan attachment to viral protein interaction is specific and hydrophobic in nature especially the secondary interactions. The interaction mainly occurs through sialylated carbohydrate domains and hydrophobic region of protein.
2 c and e are the correct options. Receptor binding to ligand is considered to be more specific as compared to viral attachment factors. Most of the time the binding to the receptor leads to higher kd value compared to viral attachment factors. Few viruses like SARS bind to 2 or more receptors to gain entry to the host cell.
3. b and f represent the correct option as viruses caan move into endocytic vesicles/lysosomes (lowere pH) and gain entry to cytoplasm where it utilises host cell machinery to produce more virus particles.
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