title: CpG-depleted adeno-associated virus vectors evade immune detection.
abstract: Due to their efficient transduction potential, adeno-associated virus (AAV) vectors are leading candidates for gene therapy in skeletal muscle diseases. However, immune responses toward the vector or transgene product have been observed in preclinical and clinical studies. TLR9 has been implicated in promoting AAV-directed immune responses, but vectors have not been developed to circumvent this barrier. To assess the requirement of TLR9 in promoting immunity toward AAV-associated antigens following skeletal muscle gene transfer in mice, we compared immunological responses in WT and Tlr9-deficient mice that received an AAV vector with an immunogenic capsid, AAVrh32.33. In Tlr9-deficient mice, IFN-γ T cell responses toward capsid and transgene antigen were suppressed, resulting in minimal cellular infiltrate and stable transgene expression in target muscles. These findings suggest that AAV-directed immune responses may be circumvented by depleting the ligand for TLR9 (CpG sequences) from the vector genome. Indeed, we found that CpG-depleted AAVrh32.33 vectors could establish persistent transgene expression, evade immunity, and minimize infiltration of effector cells. Thus, CpG-depleted AAV vectors could improve outcome of clinical trials of gene therapy for skeletal muscle disease.
authors.affiliation: Gene Therapy Program, Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
authors.forename: Susan M
authors.initials: SM
authors.lastname: Faust
authors.forename: Peter
authors.initials: P
authors.lastname: Bell
authors.forename: Benjamin J
authors.initials: BJ
authors.lastname: Cutler
authors.forename: Scott N
authors.initials: SN
authors.lastname: Ashley
authors.forename: Yanqing
authors.initials: Y
authors.lastname: Zhu
authors.forename: Joseph E
authors.initials: JE
authors.lastname: Rabinowitz
authors.forename: James M
authors.initials: JM
authors.lastname: Wilson
mesh_terms: D056704:Adaptive Immunity; D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D002213:Capsid / Q000276:immunology; D018925:Chemokines / Q000378:metabolism; D018899:CpG Islands; D004279:DNA, Viral / Q000235:genetics / Q000276:immunology*; D000229:Dependovirus / Q000235:genetics / Q000276:immunology*; D015316:Genetic Therapy; D005822:Genetic Vectors; D006367:HeLa Cells; D006801:Humans; D057131:Immune Evasion; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D018482:Muscle, Skeletal / Q000276:immunology / Q000378:metabolism; D051217:Toll-Like Receptor 9 / Q000172:deficiency / Q000235:genetics; D014161:Transduction, Genetic; D019076:Transgenes
chemical_list: D018925:Chemokines; D004279:DNA, Viral; C495370:Tlr9 protein, mouse; D051217:Toll-Like Receptor 9