A 7 kDa protein encoded by the BamHI-H gene family of Marek's disease virus is produced in lytically and latently infected cells

Marek's disease virus (MDV) BamHI-H gene family was transcribed specifically in cells infected with oncogenic MDV, and the transcripts were prematurely terminated in cells infected with non-oncogenic attenuated strains of MDV due to the amplification of a 132 bp repeat located downstream of their promoter. There are six small open reading frames in the two differently spliced and two unspliced transcripts. This report describes expression of BHa gene open reading frame A, present in 1.7 kb unspliced transcript. Antibody was raised against BHa C-terminal polypeptide. The antibody showed specific reaction to the GST fusion protein derived from BHa protein. Immunoprecipitation with the lysates of infected cells was carried out. The results indicated that 7 kDa BHa protein was immunoprecipitated from the lysates of oncogenic MDV infected chicken embryo fibroblasts (CEF) and a MSB-1 lymphoblastoid cell line derived from Marek's disease tumor but not from non-oncogenic MDV infected CEF or uninfected CEF. 36 kDa protein was co-immunoprecipitated with 7 kDa BHa protein in oncogenic MDV infected CEF but was not detected in MSB-1 cells. This is the first report to show that a small open reading frame of the BamHI-H gene family was in fact expressed in MDV infected cells.