Abstract:

The effects of PCV2 on NF-κB signal were studied to explore the modulation mechanism of PCV2 on release and changes of pro-inflammatory factors from lymphocytes in PCV2 infected piglets. Five conventional post-weaning piglets free of PCV2 and PRRSV antibody and antigen were chosen as the experiment animals. The cells isolated from spleens with pinhead of injectors were distributed into experimental group and control group. The lymphocytes of experimental group were incubated with PCV2 at 1 × 10⁵ TCID₅₀, control group was incubated with equal volume of 1640. The PCV2-inoculated and mock-inoculated lymphocytes at 0, 6, 12, and 24 h post-inoculation (HPI) were collected respectively. NF-κB was translocated into nuclear by confocal laser scanning microscope. The protein levels of NF-κB/P65 and phosphorylation-IκBα were detected by Western Blot and NF-κB DNA binding activity was detected by electrophoretic mobility shift assays (EMSA). The result of confocal laser scanning microscope showed that nuclear translocation of NF-κB/P65 after lymphocytes incubation with PCV2 increased gradually with the increased incubation time. The NF-κB/P65 proteins increased significantly (P<0.05) in PCV2-inoculated lymphocytes compared with controls at the same time. The results of NF-κB DNA binding activity revealed the same changes with NF-κB/P65 protein. The protein levels of phosphorylation-IκBα in plasma was highest at 24HPI, and the levels in experimental group were significant increasing (P<0.05) compared with control group at 6 HPI, 12HPI and 24 HPI. All the results demonstrated that PCV2 can activate the NF-κB signaling pathway through the degradation of IκB phosphorylation, and the signal could play an important role in modulating the expression of the some pro-inflammation cytokines.