Production of p16, p25, or p14 gag-specific T-cell lines. PBMC of MVV-infected sheep were used to generate gag-specific T-cell lines by two cycles of specific antigen and IL-2 stimulation. The specificity of the lines was determined using 5 × 104 T cells cultured with autologous irradiated PBMC per well in the presence of different concentrations (in micrograms per milliliter) of purified rp16 (A, closed squares), rp25 (B, closed circles), and rp14 (C, closed triangles) or pRSET C peptide (open circles) for 5 days. T cells in the presence of specific recombinant antigen but no irradiated PBMC (open squares) or T cells and irradiated PBMC with no antigen (×) were used as controls. Lymphocyte proliferation was assessed by [3H]thymidine incorporation. Data are expressed as mean cpm ± standard deviations (error bars) of triplicate cultures.