Viral protein involved in host immune evasion thereby optimizing viral growth and dissemination. Viral immune evasion strategies are typical of viruses which persist in their host throughout life. For example: Herpesviridae, Adenoviridae, Poxviridae and Retroviridae have developed subversions of the MHC class I antigen-presentation pathway. In order to reduce the effectiveness of cytotoxic T-lymphocytes immunity, they express proteins that either down-modulate MHC class I expression (degradation or mislocalization) or interfere with the antigen binding/presentation process (down-regulation of the expression of the transporter associated with antigen processing TAP). Some proteins of these virus families also down-regulate other molecules involved in immune recognition.