The Effect Of EB Virus And Encoded Protein Rta On The Transcriptional Regulation Of Interferon Pathway

EB virus infection in childhood often leads to infectious mononucleosis. Some may evolve into severe hemophagocytic syndrome and lymphoma. Interferon regulatory factor3(IRF-3) is one of the master transcription factors involved in the stringent regulation of interferon production following virus infection. Up to now, the mechnisams of EB virus evading the host immunity are still poorly understood.In the present study, differential expression of each factor induced by EB virus was detected by real time PCR in the infectious mononucleosis syndrome patients and healthy controls. Our results suggested that miRNA146a, miRNA23a, miRNA24and Rta were expressed significantly higher in the infectious mononucleosis patients than the control group, while the expression of IRF-3and IFNP were markedly decreased. But internal relations and mechanisms need to be further explored. To this end, transient transfection analysis and chromatin immunoprecipitation assays revealed that overexpression of Rta elevated the expression of E2F1and increased the binding of E2F1to the promoter of IRF-3. Mutation of E2F1binding site and knocking down of E2F1by siRNA can abolish the inhibitive effect of Rta. These results suggest that Rta represses IRF-3expression by increasing E2F1binding to IRF-3promoter. To determine the role of miRNA induced by EB virus on regulation of IRF-3, miRNA and IRF-3promoter region were cotransfected into HeLa cells. We found no promoter activity decreased significantly and it shows that miRNA did not play a negative regulatory role by IRF-3promoter region. We activated IFN(3signaling pathway via polyinosinic-polycytidylic acid (PolyI:C), using real time PCR, Western blot, luciferase reporter gene, cotransfected, overexpression, RNA interference, explored downregulation of IFNβ signaling pathway by miRNA146a induced by EB virus through TRAF6. Valproic acid as a histone deacetylase inhibitor, can upregulate the expression of IRF-3mRNA and protein in different cells. Further experiments found that valproic acid could increase the expression of histone H3, H4acetylation. Valproic acid promoted IRF-3acetylation and increased its expression. Immunofluorescence showed that IRF-3phosphorylation was significantly increased induced by valproic acid in293T cell nucleus.This study extends the study of EB virus evading the host immune and enhances our understanding of the mechanisms of IRF-3regulation via Rta and miRNA induced by EB virus. It will contribute to provide an experimental basis for future treatment of EB virus-related diseases through valproic acid.