Human cytomegalovirus (CMV, HCMV) is a member of the herpes virus group. Between 50% and 85% of human adults are infected with CMV. Once infected, the virus persists in the organism. In healthy individuals, the infection is asymptomatic, but in immunocompromised patients CMV can cause severe disease. The pp65 protein (65 kDa lower matrix phosphoprotein), also known as glycoprotein 64 or UL83, is a virion tegument protein and the main component of the enveloped subviral particle. pp65 is an immunodominant target of CD4+
as well as CD8+
T cell responses to CMV. pp65-specific T cells predominantly produce cytokines such as IFN-γ, IL-2, and TNF-α.