Synthesis of bovine leukemia virus antigens in Escherichia coli.

Plasmids were constructed by the use of pEX vectors that encode and express different parts of the bovine leukemia virus (BLV): main core protein p24, nucleic acid-binding protein p12, transmembrane protein gp30, and different segments of envelope protein gp51. Expression of fusion proteins with molecular weights higher than 117 kD for all recombinant plasmids was shown in Coomassie-blue stained gels and by Western blot analysis with rabbit anti-BLV sera. Coupling of a gp51-encoding with a p24-encoding DNA fragment in pEX vectors led to synthesis of a fusion protein that was recognized by monoclonal antibodies directed against gp51 and p24 epitopes. Using another vector, a gp51-encoding DNA fragment of BLV was expressed as a fusion protein with 100 amino acids of the MS2 polymerase. The fusion protein was recognized by monoclonal antibodies directed against gp51.