Identification of a Kd-restricted antigenic peptide encoded by murine cytomegalovirus early gene M84

The two sister cytomegaloviruses (CMVs), human and murine CMV, have both evolved immune evasion functions that interfere with the major histocompatibility complex class I (MHC-I) pathway of antigen processing and presentation and are effectual in the early (E) phase of virus gene expression. However, studies on murine CMV have shown that E-phase immune evasion is leaky. An E-phase protein involved in immune evasion, namely mO4-gp34, was found to simultaneously account for an antigenic peptide presented by the MHC-I molecule D-d. Recent work has demonstrated the induction of protective immunity specific for the E-phase protein M84-p65, one of two murine CMV homologues of the human CMV matrix protein UL83-pp65. In this study, the identification of the MHC-I K-d-restricted M84 peptide (297)AYAGLFTPL(305) is documented. This peptide is the third antigenic peptide described for murine CMV and the second that escapes immunosubversive mechanisms.