Figure 3

PRRSV-specific cell-mediated immune response as determined by the IFN-γ ELISPOT, days 21 to 84 pi.

Peripheral blood mononuclear cells (PBMC) were stimulated with either of the PRRSV strains (3262 or 3267) used in the study. Results are shown (columns) as average frequencies of virus-specific IFN-γ secreting cells per million of PBMC obtained in the ELISPOT with the corresponding standard deviations (bars). For each experiment the results of ELISPOT are shown in two series: darker shadowed columns indicate results obtained after in vitro stimulation with the same PRRSV strain with which had been immunized initially (homologous) while lighter coloured bars show the results of in vitro stimulation with other PRRSV isolate used in the present study (heterologous). Asterisks indicate significant differences between results obtained in the homologous and the heterologous ELISPOT for each experiment (*p < 0.05; **p < 0.01; † p = 0.07) at a given time point. Letters indicate significant differences (p < 0.05) among different time points in a given series. For each time point and series, the number of responding pigs over the total number of examined pigs is shown. 3A = Experiment 1 (inoculation with strain 3262); 3B = Experiment 2 (inoculation with strain 3267). dpi = days post-inoculation.