Immunomodultory Effect Of Receptor CD300a On Inflammatory Cytokines After Infection Of Bovine Mononuclear Macrophages

CD300 family molecules are members of the superfamily of immune cell surface receptors and immunoglobulins,which play an important role in immune response.In order to explore the role of inhibitory receptor CD300a in the immune regulation mechanism of bovine infectious rhinotracheitis virus（Infectious Bovine Rhinotracheitis Virus,IBRV）,a strain of IBRV was isolated and the growth of IBRV in immortalized mononuclear macrophages was detected by quantitative PCR.To establish a fluorescence quantitative method of bovine CD300a,IL-1β,IL-6,IL-8,IL-10 and TNF-αto detect the transcriptional changes of CD300a and various cytokines at 0,6,12,24,48,72,96,120h after IBRV infection,and to detect the effects of overexpression and silencing of CD300a on IBRV replication and transcription of various cytokines.The results showed that:（1）IBRV showed typical cytopathic effect on MDBK cells.TCID50 10^-5.23/μL IBRV proliferated rapidly in bovine mononuclear macrophages at 0,24h,then slowed down after 24h,entered a plateau phase at 48h,and then stopped replicating.（2）the fluorescence quantitative detection methods of CD300a and inflammatory cytokines established in this study showed that the standard curve correlation coefficient was more than 0.998 and the amplification efficiency was more than 92.2%.（3）the expression of CD300a in macrophages infected with IBRV was higher than that in the control group at 8 time periods,while the relative expression of IL-1βand IL-8 decreased,while the relative expression of IL-6,IL-10 and TNF-αincreased.（4）the overexpression of CD300a gene was successfully overexpressed and silenced by lentiviral vector,the results showed that overexpressed CD300a was regulating the replication of IBRV DNA and the transcription of IL-1βand IL-10,while silencing CD300a was regulating the transcription of IL-6,IL-8 and TNF-α.The purpose of this study was to explore the regulation of inflammatory cytokines and virus replication by CD300a in mononuclear macrophages infected by IBRV,which provides a basis for further study of the immune mechanism of IBRV.