FIG. 1.

(A) BHV-1-specific CTL were induced in PBMC bulk cultures stimulated with UV-inactivated BHV-1 (MOI, 10). The effector cells were PBMC isolated from BHV-1 immunized cattle and stimulated with UV-inactivated BHV-1 and rhIL-2 at 80 U/ml for 7 to 10 days. Target cells were macrophages recovered from PBMC and pulsed for 2 h with BHV-1 polypeptides and 1 h with ⁵¹Cr before the CTL assays. The CTL assay mixtures were incubated for 6 h. Effector cells from a nonimmunized seronegative animal served as a control. This result is representative of 12 separate experiments. (B) BHV-1 polypeptide antigen (Ag) concentration was titrated for CTL activity. At an effector-to-target (E:T) ratio of 50:1, BHV-1-specific lysis increased as the BHV-1 polypeptide concentration increased. Samples were counted as positive when the mean lysis exceeded the medium control by 3 standard deviations. The spontaneous release was less than 25% of the maximum release. This experiment was repeated once with similar results.