Epitope mapping of bovine leukemia virus transactivator protein Tax.

The immunogenicity of the bovine leukemia virus (BLV) transactivator protein (tax) was studied by mapping its B-cell and T-cell epitopes. Peptides (18 to 20-mer) overlapping by 10 amino acids, spanning whole amino acid sequence of BLVtax were synthesized. Recombinant BLVtax protein was used to immunize two different strains of mice, C57BL/6 and BALB/c. B-cell and T-cell epitopes of recombinant BLVtax protein was determined by screening all the 30 synthetic peptides, against immune serum in ELISA for antibody reactivity, and against immune spleen cells in lymphocyte proliferation assay for T-cell stimulation. Peptides with amino acids at position 111-130 and 131-150 were T-cell epitopes for C57BL/6 and BALB/c mice immune cells, respectively. B-cell epitope was mapped to amino acid sequence at 261-280 in both strains of mice. These results imply that BLVtax protein contains some of BLV- immunodominant epitopes and this information may be applied for designing an effective peptide vaccine capable of inducing neutralizing antibodies as well as cellular immunity.