A pathogenic immune response targeting aquaporin-4 (AQP4) causes neuromyelitis optica spectrum disorder (AQP4 NMOSD), a disabling neurological illness that leads to blindness and paralysis. Recent advances in treatment for AQP4 NMOSD have improved its prognosis but are associated with increased risk of serious infections. As an autoimmune neurological illness with a well-defined autoantigen, AQP4 NMOSD should be amenable to a cure by antigen-specific ablation or tolerization. However, preclinical testing of antigen-specific tolerizing therapy for AQP4 NMOSD remains hampered by the lack of an animal model that recapitulates the autoimmunity and the pathology in the same animal. Current animal models of AQP4 NMOSD require adoptive transfer which introduces confounding variables that are difficult to resolve. The objective of this proposal is to develop a model that recapitulates the autoimmunity and the pathology of AQP4 NMOSD in the same animal and thereby develop an animal model suitable for preclinical testing of antigen-specific tolerization therapies. Aim 1.1 will establish anti-AQP4 autoimmunity in the AQP4 null (AQP4.lacZ) mouse. Aim 1.2 will test two methods to restore AQP4 expression in the AQP4.lacZ mouse: 1) AAV-mediated AQP4 transduction and 2) inducible (tamoxifen) and conditional (GFAP promoter) Cre recombinase system to restore AQP4 expression in the AQP4.lacZ mouse. Aim 1.3 will test the hypothesis that restoring AQP4 expression following immunization against AQP4 in the AQP4 null mouse will result in AQP4-directed autoimmunity and pathology in the same animal. The successful completion of the proposed research is expected to deliver a new animal model that more fully recapitulates the autoimmunity and the pathology of AQP4 NMOSD, and thereby overcome the shortcomings of the current models. Once this model is developed, it will make a positive impact by facilitating preclinical studies aimed at developing antigen-specific ablation/tolerization therapies as cure for AQP4 NMOSD.