Experimental intracerebral vaccination protects mouse from a neurotropic virus by attracting antibody secreting cells to the CNS.

In previous studies, we showed that intracerebrally (IC) immunized mice had antigen-specific antibodies (Abs) in cerebrospinal fluid and could survive lethal doses of transneurally spreading viruses. To better understand the mechanisms behind this, immune responses in both the central nervous system (CNS) and lymphoid organs following intracerebral immunization against pseudorabies virus (PRV) were investigated by focusing on antibody secreting cells (ASCs). IC immunized mice had significantly higher PRV-specific serum Abs and neutralizing Abs titers than SC immunized mice. Spleen and cervical lymph nodes (CLNs) of IC immunized mice produced significantly more PRV-specific Abs than that of SC immunized mice. ASCs, immunoglobulin and mRNAs of IgG, CXCL9, 10, 13 and BAFF were predominantly detected in the brain of IC immunized mice, but not in SC immunized mice. IC immunized mice (86%) survived more than subcutaneously (SC) immunized mice (33%) by suppression of virus propagation, when PRV was inoculated directly into the brain. In conclusion, IC immunization induced more effective immune responses to protect the CNS from PRV infection by attracting ASCs into the CNS and inducing much more PRV-specific serum neutralizing Abs. This approach may have important implications as a novel treatment procedure for neurotropic virus infections in both humans and animals.