PRRSV感染PAM中猪FcγRⅢ介导的免疫抑制反应

Immunosuppression mediated by porcine FcγRⅢ in PRRSV infection to PAMS

目的：为研究猪FcγRⅢ介导猪繁殖与呼吸综合征病毒（ Porcine reproductive and respiratory syndrome virus ， PRRSV）的免疫抑制反应。方法：本研究将含有200个TCID50的PRRSV、脂多糖（Lipopolysaccharide，LPS）（100 ng/ml）和纯化鼠抗猪FcγRⅢIgG（550μg/ml）分别处理猪肺泡巨噬细胞（ Pulmonary alveolar macrophages cell ，PAM），同时用纯化鼠抗猪FcγRⅢIgG处理PAM细胞后接种PRRSV，并设PAM细胞对照组。各组分别培养12、24、36、48、60、72 h后收集细胞及上清，用已经建立的绝对荧光定量PCR方法检测接毒组不同时间段的PRRSV复制水平，并用相对荧光定量PCR方法检测各组PAM细胞中IFN-α、TNF-α的mRNA转录水平。结果：PRRSV在感染PAM细胞后12～24 h期间可促进IFN-αmRNA转录水平，36～72 h期间抑制IFN-αmRNA转录水平，之后IFN-α的mRNA转录水平恢复正常；TNF-αmRNA转录水平在感染后12～72 h均略微上调。 LPS处理PAM细胞后，IFN-α、TNF-αmRNA转录水平均上调。用纯化鼠抗猪FcγRⅢIgG处理猪PAM细胞后，选择性激活猪PAM细胞表面FcγRⅢ，IFN-α、TNF-αmRNA转录水平显著下调，用PRRSV感染选择性激活猪PAM细胞表面FcγRⅢ后显著抑制抗病毒因子IFN-α、TNF-αmRNA转录水平。结论：FcγRⅢ的选择性激活抑制了宿主细胞的抗病毒因子水平及在PRRSV感染过程中的天然抗病毒免疫反应。

Objective：To study immunosuppression mediated by the porcine FcγRⅢ in porcine reproductive and respiratory syndrome virus （ PRRSV ） infection to pulmonary alveolar macrophages （ PAMS ）.Methods： In this study pulmonary alveolar macrophages cells were treated with containing 200 TCID50 PRRSV,lipopolysaccharide （LPS） （100 ng/ml） and purified mouse anti-pig FcγRⅢIgG （550 μg/ml） separately,simultaneously,PAM cells treated with purified mouse anti-pig FcγRⅢIgG （550 μg/ml） was infected by 200 TCID50 PRRSV ,untreated PAM cells as the control group.Each group were post-cultured 12,24,36,48,60,72 h, the cells and the supernatant were collected.The dynamic variation of PRRSV RNA copies in inoculation group were detected by using real-time fluorescence quantitative PCR method.mRNA level of IFN-αand TNF-αin each group were detected by using relative fluorescence quantitative PCR.Results：The result showed that mRNA level of IFN-αwas improved during PRRSV infection to PAMS 12-24 h,and mRNA level of IFN-αwas inhibited during 36-72 h,then mRNA level of IFN-αrecovered normally; mRNA level of TNF-αwas increased slightly post-infection 12-72 h.IFN-αand TNF-αmRNA levels of PAM cells treated with LPS were both up-regu-lated,using the purified mouse anti-pig FcγRⅢ IgG to treat the PAM cells,selective activation of porcine FcγRⅢ in the PAM cells down-regulated significantly mRNA levels of IFN-αand TNF-α.PRRSV infection assay mediated by selective activation FcγRⅢof the PAM cells inhibited antiviral cytokine （ IFN-αand TNF-α） mRNA levels.Conclusion：The results show selective activation of FcγRⅢinhibited significantly mRNA levels of the antiviral cytokine IFN-αand TNF-αof host cells,and innate antiviral immune response to PRRSV infection.