Adaptive Immunity to Viruses

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Humoral

• Production of neutralising antibody
• Antibody-dependent cell mediated cytotoxicity (ADCC)

Antibody-labelled cells can be targeted by NK Cells as another defence against viral infection. Antibody produced against viral protein can attach to infected cells during their budding phase, which effectively labels them for NK targeting. NK cells express Fcγ receptors with which to detect such cells. Once activated, they release a host of enzymes to induce apoptosis of the budding cell.

Cell-Mediated

• CD8+ T-cell mediated killing of virus infected cells
  • Main cells involved in the immune response to intracellular virus infection
  • Recognition of MHC I-peptide complex
  • Infected cells are killed by apoptosis
    • Perforin and granzymes activate the caspase cascade
    • Fas-ligand triggers the Fas-mediated apoptosis pathway
    • Cytotoxic cytokines (especially TNF-α & TNF-β lymphotoxin) act on TNF receptors to induce programmed cell death

Also see Immunity to Viruses