MAREKS-DISEASE VIRUS TYPE 1-SPECIFIC PHOSPHORYLATED PROTEINS PP38 ANDPP24 WITH COMMON AMINO-ACID TERMINI ARE ENCODED FROM THE OPPOSITE JUNCTION REGIONS BETWEEN THE LONG UNIQUE AND INVERTED REPEAT SEQUENCES OFVIRAL GENOME

The nucleotide sequence of the junction region between the long unique (U-L) and terminal inverted repeat (TR(L)) sequences of Marek's disea se (MD) virus type 1 (MDV1) DNA revealed the presence of a rightward o pen reading frame of 155 amino acids. The ORF inserted into an eukaryo tic expression vector transiently expressed an antigen in the cytoplas m of COS7 cells which reacted with the monoclonal antibody M21 against an MDV1-specific phosphorylated protein complex consisting of at leas t the proteins pp38 and pp24. In addition, RNA synthesized in vitro fr om the ORF under the control of the T7 promoter was translated in vitr o using rabbit reticulocyte lysates. A polypeptide of about 24 kDa was immunoprecipitated with M21 antibody. Thus, the MDV1-specific phospho rylated proteins pp38 and pp24 with common amino termini are encoded i n the opposite junction regions between the U-L and IR(L) and between the U-L and TR(L), respectively, of the MDV1 genome. The pp38 gene is transcribed leftward from the viral genome, while the pp24 gene was sh own here to De transcribed rightward in a MD tumor cell line as well a s in cells productively infected with MDV1. (C) 1994 Academic Press, I nc.