[Campbell Biology P.1008] A virus infects a host cell and replicates inside it. If this infec... | Practice Question

A virus infects a host cell and replicates inside it. If this infected host cell completely loses the ability to synthesize and display Major Histocompatibility Complex MHC molecules on its surface, how would T cell recognition be affected?

  • A: T cells would directly recognize the intact viral particles on the cell surface, leading to a normal immune response.
  • B: B cells would compensate by recognizing the viral antigens directly on the infected cell, activating a strong antibody response.
  • C: The infected cell would fail to present viral antigen fragments on its surface, preventing T cells from recognizing the infection and mounting an effective immune response against it.
  • D: T cells would still be able to recognize the infected cell, but their activation would be delayed due to the absence of MHC molecules.

Explanation

The text explicitly states: 'antigen receptors of T cells bind only to fragments of antigens that are displayed, or presented, on the surface of host cells. The host protein that displays the antigen fragment on the cell surface is called a major histocompatibility complex MHC molecule. By displaying antigen fragments, MHC molecules are essential for antigen recognition by T cells.' Therefore, without MHC molecules, T cells cannot recognize the infected cell.