A nonstructural polypeptide encoded by immediate-early transcription unit 1 of murine cytomegalovirus is recognized by cytolytic T lymphocytes

We have constructed target cells by cotransfection of the MHC gene
Ld and fragments of murine cytomegalovirus (MCMV) DNA coding for
nonstructural immediate-early (IE) proteins. Transfectants were
tested by using CTL clone IE1 with specificity for an IE epitope
presented in association with Ld. Data show that clone IE1
recognizes a product of the ie1 transcription unit of MCMV, and
that its specificity is shared by approximately 25% of polyclonal
IE-specific CTL. The results provide the first definite evidence
that expression of a herpes virus IE gene encoding a regulatory
protein gives rise to antigen expression detectable by specific CTL