FIG. 3.

Proliferative responses of lymphocytes from bank voles immunized with hantavirus rN proteins after in vitro recall. Single-cell suspensions of spleen lymphocytes from individual bank voles immunized with PUUV (A), TOPV (B), ANDV (C), or DOBV (D) rN protein were cultured in the presence of PUUV rN (▪) or DHFR control protein (□). Values are given as means ± standard deviations of SI, of individual bank voles in groups of five or six animals. The dashed lines represent the cutoff for a positive response, which was set to SI = 4. The range for spontaneous proliferation (medium alone) was 411 to 18,370, and that for positive control proliferation (5 μg of concanavalin A per ml) was 34,879 to 200,404. The range for proliferation of experimental samples stimulated with titrated rN proteins was 331 to 122,608, and that for experimental samples stimulated with titrated DHFR control protein was 197 to 42,020. The lowest count for an experimental sample above the set cutoff was 3,245 cpm.