Immunomodulation Of CD209A And CD209B On Dendritic Cells During Japanese Encephalitis Virus Infection

Japanese encephalitis(JE)is a zoonosis caused by Japanese encephalitis virus(JEV),which belongs to the genus flavivirus member of the flaviviridae and spreads mainly through Culex mosquitoes.Although JEV vaccine has been widely used,the transmission range of JE still exhibits an increasing tendency.This study explored the immune function of DC-SIGN(Dendritic Cell-Specific Intercellular adhesion molecule-3-Grabbing Non-integrin,DC-SIGN)during JEV infection in order to better understand of JEV pathogenesis and provide a better treatment.Based on the previous results of RNA sequencing,three expression-altered members of DC-SIGN family were selected:DC-SIGN(CD209A),DC-SIGNR1(CD209B)and DC-SIGNR 2(CD209C)for further verification with spleen samples of mice infected with JEV virulent strain P3 and vaccine strain SA14-14-2 at three days post infection.The results indicated that the expression of CD209A on CD11c~+dendritic cells and F4-80~+macrophages was significantly lower in the mice infected with JEV virulent strain P3 than that of the control group.However,the expression of CD209B was significantly increased on CD11c~+dendritic cells of the mice infected with JEV virulent strain P3.Then the expression of CD209A and CD209B were determined on the differentiation of BMDCs(Bone Marrow-Derived Dendritic Cells,BMDCs),during the maturation of which the expression of CD209A and CD209B increased in vitro.Then,stable cell lines of DC2.4highly expressing CD209A or CD209B were constructed in vitro to explore the effect of CD209A or CD209B on JEV replication and its function on DCs.The results demonstrated that over-expression of CD209A promoted JEV replication,while over-expression of CD209B had no significant effect on JEV replication on DC2.4 cells.The co-culture of EL-4 cells with DC2.4 cells after over-expression of CD209A or CD209B showed that both of them promoted the proliferation of EL-4 cells.In conclusion,the expression of CD209A on dendritic cells significantly decreased after JEV infection in vivo.The vitro experiments showed that over-expression of CD209A on DC2.4 cells promoted the replication of JEV.These results suggest that dendritic cells protect cells from JEV infection by down-regulating CD209A.In addition,the co-culture of EL-4 cells with DC2.4 cells after over-expression of CD209A or CD209B showed that both of them promoted the proliferation of EL-4 cells,indicating that both CD209A and CD209B play a vital role in adaptive immune response.This study lays a foundation for further research on the immune regulation function of DC-SIGN,providing a potential drug target for the treatment of Japanese encephalitis.