Rabies Virus Expressing Dendritic Cell-activation Molecules Enhance The Innate And Adaptive Immune Response

Recently it was found that activation of the innate immune responses is one of the mechanisms by which rabies virus (RV) is attenuated. Induced innate response genes include inflammatory chemokines (RANTES, MIP-1 , IP-10, etc) and cytokines (IL-6, IL-1 , and TNF- ), IFN and IFN-related genes (IFN- , STAT1, Mx-1), and Toll-like receptors (TLRs1-3). These innate immune molecules are capable of inducing activation of dendritic cells triggered the strongest adaptive immune responses and provided the best protection, so we incorporate the immunostimulatory molecules into chimeric RVs to increase their efficacy. We use of dendritic cell-activation molecules as genetic adjuvants for rabies virus vaccines try to affect the very early events of an immune response and induce much higher specific neutralizing antibody responses, which includes maturation and migration of DCs from the site of inflammation to the draining lymph nodes.The recombinant rabies virus (rRV) carrying chemokines and cytokines were constructed from the SAD L16 strain which mutated the position 194 and 333 amino acids on the G protein. To determine the function of rRVs with expressing dendritic cell-activation molecules in innate and adaptive immunity, we generated rRVs that expressed murine granulocyte-macrophage colony-stimulating factor (mGM-CSF), murine CCL22 (mCCL22) and Macrophage Inflammatory Protein 1 alpha(mMIP-1 ). The rRVs carrying dendritic cell-activation molecules induced much higher increases of RV-specific antibody titers, compared to those responses elicited by just backbone rRV. The rRVs expressing each of these molecules are avirulent since infection with the highest possible dose did not induce any diseases in adult mice but have limited pathogenicity in the baby mice. Peripheral immunization with each of the virus the viral total RNA and insert gene in the mouse muscle were examined by an RT-PCR analysis for rRVs infected mice at 3 and 6dpi. There was almost the same RV genome in rRVs infected mice at the onset of infection, of course, the insert gene products were increased after immunization with recombinant virus respectliy. Double positive numbers of B cells and DC cells were assessed by flow cytometry in the lymph nodes and blood. When cells were stimulated specifically by rLBNSE-GM-CSF, rLBNSE-MDC, and rLBNSE-MIP-1 double positive B cells and DC cells showed a higher signal than rLBNSE B cells in the lymph nodes and blood. These results s ggested that the B and DC cells were more activated by different rRVs with inserts than backbone virus.One single immunization can induce 100% protection in mice against the challenge infection with virulent rabies virus. Together our results indicate that these recombinant rabies viruses expressing dendritic cell-activation molecules enhance humoral and cellular immune responses and have the potential to be developed as the next generation of rabies virus vaccines.