Final answer:
The class II MHC molecule of infected cells must go through the process of antigen processing and presentation before presenting the antigen to be detected by a T cell.
Step-by-step explanation:
The process that the class II major histocompatibility (MHC) molecule of infected cells must go through before presenting the antigen to be detected by a T cell is antigen processing and presentation. Antigens are internalized by antigen-presenting cells (APCs) through phagocytosis, digested, and then brought to the surface of the cell associated with MHC II molecules. This complex of antigen and MHC II is recognized by T cells, leading to T cell activation.