Identification of the gene product encoded by the PstI repeats (IR4) of the Epstein-Barr virus genome.

The Epstein-Barr virus (EBV) genome contains several clusters of internal repeats (IR). Here we report the identification of the repetitive protein encoded by the IR4 region (PstI repeats). This IR4 protein is inducible by TPA and n-butyrate and belongs to the EA-D subgroup of the EBV-encoded early antigens. Its molecular size varies between different EBV strains. Furthermore, several human EBV-positive sera reacted with a part of the IR4 protein expressed as a fusion protein. These data indicate the in vivo expression of this protein during the course of an EBV infection.