T helper 1-type cytokine transcription in peripheral blood mononuclear cells of pseudorabies virus (Suid herpesvirus 1)-primed swine indicates efficient immunization

The induction of porcine cytokines, which are believed to be important for the regulation of T helper (Th)1- and Th2-specific immune responses of pigs , was analysed after in vitro restimulation with a herpesvirus, Suid herpes 1 (pseudorabies virus [PRV]), in peripheral blood mononuclear cells (PBMC) . To this end, quantitative, competitive reverse transcription-polymerase c hain reaction (RT-qcPCR) was established using constructed heterologous DNA MIMICS, which contain cytokine- or glyceraldehyde-3-phosphate dehydrogenas e (GAPDH)-specific primer-binding sites. This is a simple method that allow s reliable determination of the differing regulation of cytokine mRNAs spec ific for porcine interleukin (IL)-2, -4 and -10, interferon gamma (IFN-gamm a) and the housekeeping gene, GAPDH, as an endogenous control. PBMC derived from naive (innate response) and PRV-primed (memory response) outbred swin e were analysed comparatively. The results demonstrated that restimulation with PRV significantly enhanced the transcription of Th1-type cytokines (IL -2 and IFN-gamma) but not of Th2-type cytokines (IL-4 and IL-10). This viru s-specific cytokine response was only found with PBMC from swine protected against lethal PRV challenge infection, but not with naive PBMC or with PBM C from pigs immunized with plasmid DNA encoding PRV glycoprotein gC. Notabl y, PBMC derived from immune and naive pigs constitutively produced relative ly high amounts of IL-10-specific mRNA, exceeding that of GAPDH mRNA, indep endently of the addition of viral antigen or the mitogen concanavalin A (Co n A). The results of this work should help to provide a better understandin g of the effector cell/cytokine network response to infection with, or vacc ination against, PRV. Additionally, the simple, reliable and sensitive RT-q cPCR, when used to determine the porcine cytokine pattern, might be of prog nostic value for the induction of protective immunity.