FIG. 4.

Proliferative responses of PBMC from RAP-1α1-immunized cattle to recombinant proteins containing Th cell epitopes. PBMC obtained prior to B. bigemina challenge were cultured for 6 days with 5 and 25 μg of antigen per ml consisting of B. bigemina (Mexico) merozoite CM antigen (closed triangles) or recombinant MBP fusion proteins consisting of RAP-1 protein (closed circles), aa 144 to 187 (open triangles), CT-1 (aa 386 to 480; closed squares), and MBP (open circles). Cells were radiolabeled for 4 h with [¹²⁵I]iododeoxyuridine, harvested, and counted. The results are presented as the means ± 1 standard deviation of triplicate cultures.