| Porcine reproductive and respiratory syndrome (PRRS) is caused by porcine reproductive and respiratory syndrome virus (PRRSV), PRRSV infection induces serious interstitial pneumonia, it is revealed that inflammatory factors play a key role in diseases induced by PRRSV, however the mechanism is still not better understood. RANTES (regulated upon activation, normally T-cell expressed and presumably secreted) is an important member of CC chemokine family, it is also an inflammatory factor, which can regulate migration of leukocytes to sites of infection by coordinating and activating the immune response, which enables the host to eliminate offending pathogens. Till now, the relationship between PRRSV and RANTES is not clear. Is the expression of RANTES affected by PRRSV infection? In order to better understand of this, we analyzed the chemokine RANTES expression and the signal pathways after PRRSV infection. The main research works were as following:1. PRRSV infection up-regulated RANTES in Marc-145 cellsReal-time PCR and RANTES promoter luciferase reporter system assays showed PRRSV infection up-regulated RANTES gene transcription was in a time and dose dependent manner. UV-inactivated PRRSV could not active RANTES gene transcription. The activation of RANTES by PRRSV was in a dose dependent manner and had relationship with the PRRSV replication.2. PRRSV-induced RANTES transcription concerned with NF-κB in Marc-145 cellsIn order to determine the role of regulatory elements, RANTES promoter mutagenesis luciferase reporter genes were used to indicate that the nuclear factor(NF-KB) site played a key role in PRRSV-induced RANTES transcription, and interferon-stimulated responsive element (ISRE) had no effect in RANTES transcription. CRE and NF-IL6 had no obviously contribution. In order to better understand the role of NF-κB, we used BAY11-7082, an inhibitor of the nuclear factorκB (NF-κB) and mIκBα, a dominant-negative mutant of IκB kinase to analyze, the result showed NF-κB signaling pathway took part in PRRSV-induced RANTES transcription.3. Studies on the upstream signaling pathway that concerned with PRRSV-induced RANTES transcriptionIn order to reveal the upstream signaling pathway that concerned with PRRSV-induced RANTES transcription, fusion trans-activator plasmid pFA2-Elkl were used to certify that PRRSV infection in Marc-145 cells could active MAPK signaling pathway. We used the inhibitors of p38,JNK and Erkl/2 to treat with Marc-145 cells, U0126 significantly affect RANTES transcription in a dose dependent manner, co-transfection mErkl/2 also down-regulated the transcription of RANTES. All about these identified ERK1/2 signaling pathway concerned with PRRSV-induced RANTES transcription. In addition, we investigated the upstream signaling pathway of NF-κB:we use the main adaptor molecules(including,MyD88,TRIF,TRAF6,TRAF2,RIG-I) of TLR and RIG-I signal pathway, the results demonstrated that PRRSV-induced RANTES activity was related with the adaptor TRIF, MyD88 and TRAF6, whereas unrelated with RIG-I and TRAF2. All about this identificated that PRRSV-induced RANTES through TLR signal pathway, not RIG-I. |
