6. Adaptive Immunity 3

Question 1

What is Antigen Processing?

Answer 1

• Enzymatic process of degrading proteins through proteases into antigenic peptides
• Antigen processing requires energy (ATP) and movement of endocytic vesicles

Question 2

Endogenous Antigens

Answer 2

MHC I

• Intracellular Antigen
• Antigen processing to peptides in proteasome
• Peptide transport into ER, facilitated by TAP 1 and TAP 2
• Peptide binding by MHC class I
• MHC Class I presents peptide at cell surface

Question 3

Exogeneous Antigens

Answer 3

MHC II

• Endocytosis of pathogen
• Breakdown of its proteins into peptides
• Complexed with MHC class II
• MHC class II presents peptide at cell surface

Question 4

How does the HSV evade the immune system?

Answer 4

HSV ICP47

• selectively binds TAP
• inhibits transfer of peptides into ER

Question 5

Where does MHC II loading takes place?

Answer 5

• in proteasome
• acidic pH here required for degradation into peptides
• Invariant chain is degraded and CLIP is exchanged with foreign peptide

Question 6

How do some viruses evade the MHC II pathway?

Answer 6

glycoprotein B in HSV inhibits production of invariant chain peptide