ลักษณะการสร้างไซโตไคน์ในเม็ดเลือดขาว ชนิดนิวเคลียสเดียวของสุกร ที่ติดเชื้อไวรัสพี อาร์ อาร์ เอส มาก่อนและกระตุ้นด้วยไวรัสสายพันธุ์ต่างชนิด / วีระศักดิ์ สะดะ = Characterization of cytokine production in the peripheral blood mononuclear cells of pigs recovered from porcine reproductive and respiratory syndrome virus (PRRSV) infection and reactivated with heterologous strains / Weerasak Sada
The objective of this study was to determine the effects of previous exposure to PRRSV on the cytokine production by porcine peripheral blood mononuclear cells (PBMC) upon in vitro re-activation with various PRRSV strains. PRRSV-seronegative pigs were intranasally inoculated with the Thai PRRSV isolates; US (01NP1) and EU genotype (02SB3). At 3 weeks post-inoculation, blood samples were collected, PBMC samples were isolated and in vitro cultured with various PRRSV strains. Results showed that previous exposure with virulent PRRSV increased background IL-10 production by the PBMC and increased IL-10 production upon re-activation with virulent PRRSV strains. All studied lymphocyte populations (CD4[superscript +], CD8[superscript +] and CD4[superscript +]CD8[superscript +]) were found to produce IL-10. Enhanced IFN-[gamma] production by the memTh (CD4[superscript +]CD8[superscript +] subpopulation) when activated with heterologous PRRSV strains was observed. In addition, PBMC from pigs previously vaccinated with PRRSV-EU- vaccine were in vitro activated with various PRRSV strains. Interestingly, significant effects on IL-10 and IFN-[gamma] productions were observed. In an in vivo experiment, pigs were vaccinated with modified live-PRRSV-EU twice at 3 weeks interval. Three weeks after the 2nd vaccination, pigs were challenged with yhe virulent Thai PRRSV of both genotypes. The results demonstrated an enhanced IL-10 production, and a reduction of IFN-[gamma] production by the PBMC of vaccinated pigs when challenged with the homologous genotype. The heterologous challenge of vaccinated pigs did not have significant effect on the cytokine production when compared with the non-vaccinated challenged group. Our result confirmed that pre-exposure with PRRSV could enhance IL-10 production by porcine PBMC. In addition, strains and virulence of PRRSV could influence the patterns and levels of cytokine production by porcine PBMC.