Figure 1: Strategies of viruses to evade NK cell-mediated immune surveillance. A) Upon recognition of virus-infected cells by activating NK cell receptors, NK cells secrete cytokines and kill infected cells to control viral infection. However, viruses have evolved strategies to evade NK cell immune surveillance, such as listed in B-E. B) Viruses encode their own MHC class I homolog to inhibit NK cell function through binding to NK cell inhibitory receptors. C) Viruses encode anti-inflammatory cytokine IL-10 mimicry to suppress NK cell function. D) Viruses encode soluble ligands binding to NK cell activating receptor NKG2D to block NK cell recognition of infected cells. E) Viruses directly infect NK cells resulting impaired NK cell function and NK cell apoptosis.