Host immune response to cytomegalovirus

To confirm that immediate-early (IE) genes of murine
cytomegalovirus (MCMV) give rise to antigens recognized by specific
cytolytic T lymphocytes (CTL), a 10.8-kilobase fragment of MCMV DNA
which is abundantly transcribed at IE times was transfected into L
cells expressing the Ld class I major histocompatibility
glycoprotein. The viral genome fragment contains sequences of the
three IE transcription units of MCMV: ie1, ie2, and ie3. In the
transfected cell lines, only the predominant 2.75-kilobase
transcript of ie1 and its translation product pp89 could be
detected. The transfectants were analyzed for membrane expression
of an IE antigen by employing clone IE1, an IE-specific CTL clone,
as the probe. Only cells that expressed both the MCMV IE gene(s)
and the Ld gene were recognized by the CTL clone.