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Cellular and Molecular Biology

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MHC Presentation of M. tuberculosis Antigens

CELLS-QFAVF$

The causative agent of Tuberculosis, Mycobacterium tuberculosis, induces host cells to engulf them via phagocytosis. Once inside the host cell in the phagosome, M. tuberculosis is able to block the fusion of the phagosome with the lysosome and remains protected within the phagosome where it replicates. As a consequence, M. tuberculosis is considered an intracellular pathogen.

Given this lifestyle, which of the following statements BEST describes how you would expect M. tuberculosis antigens to be presented on the surface of an infected dendritic cell?

A

The phagosomes containing M. tuberculosis would fuse with endosomal compartments that contain MHC I molecules and antigen would be loaded. MHC I molecules displaying antigen would then transit to the surface of the cell via exocytosis.

B

The phagosomes containing M. tuberculosis would fuse with endosomal compartments that contain MHC II molecules and antigen would be loaded. MHC II molecules displaying antigen would then transit to the surface of the cell via exocytosis.

C

The phagosomes containing M. tuberculosis would deliver antigen to the rough endoplasmic reticulum (RER), where it would be loaded onto MHC I molecules. MHC I molecules displaying antigen would then transit through the Golgi and the secretory pathway to reach the surface of the cell.

D

The phagosomes containing M. tuberculosis would deliver antigen to the rough endoplasmic reticulum (RER), where it would be loaded onto MHC II molecules. MHC II molecules displaying antigen would then transit through the Golgi and the secretory pathway to reach the surface of the cell.