title: Adeno-associated virus capsid antigen presentation is dependent on endosomal escape.
abstract: Adeno-associated virus (AAV) vectors are attractive for gene delivery-based therapeutics, but data from recent clinical trials have indicated that AAV capsids induce a cytotoxic T lymphocyte (CTL) response that eliminates transduced cells. In this study, we used traditional pharmacological agents and AAV mutants to elucidate the pathway of capsid cross-presentation in AAV-permissive cells. Endosomal acidification inhibitors blocked AAV2 antigen presentation by over 90%, while proteasome inhibitors completely abrogated antigen presentation. Using mutant viruses that are defective for nuclear entry, we observed a 90% decrease in capsid antigen presentation. Different antigen presentation efficiencies were achieved by selectively mutating virion nuclear localization signals. Low antigen presentation was demonstrated with basic region 1 (BR1) mutants, despite relatively high transduction efficiency, whereas there was no difference in antigen presentation between BR2 and BR3 mutants defective for transduction, as compared with wild-type AAV2. These results suggest that effective AAV2 capsid antigen presentation is dependent on AAV virion escape from the endosome/lysosome for antigen degradation by proteasomes, but is independent of nuclear uncoating. These results should facilitate the design of effective strategies to evade capsid-specific CTL-mediated elimination of AAV-transduced target cells in future clinical trials.
authors: Gene Therapy Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA. chengwen@med.unc.edu
authors: Chengwen
authors: C
authors: Li
authors: Yi
authors: Y
authors: He
authors: Sarah
authors: S
authors: Nicolson
authors: Matt
authors: M
authors: Hirsch
authors: Marc S
authors: MS
authors: Weinberg
authors: Ping
authors: P
authors: Zhang
authors: Tal
authors: T
authors: Kafri
authors: R Jude
authors: RJ
authors: Samulski
mesh_terms: D000626:Aminopeptidases / Q000378:metabolism; D000818:Animals; D017951:Antigen Presentation; D000956:Antigens, Viral / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D000998:Antiviral Agents / Q000494:pharmacology; D020126:Brefeldin A / Q000494:pharmacology; D019556:COS Cells; D036022:Capsid Proteins / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D002522:Chlorocebus aethiops; D045142:Cross-Priming; D000229:Dependovirus / Q000235:genetics / Q000276:immunology* / Q000502:physiology; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases / Q000378:metabolism; D011992:Endosomes / Q000378:metabolism* / Q000821:virology; D015316:Genetic Therapy; D057809:HEK293 Cells; D006801:Humans; D051379:Mice; D008822:Mice, Transgenic; D019913:Nuclear Localization Signals / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D021381:Protein Transport; D059748:Proteolysis; D012697:Serine Endopeptidases / Q000378:metabolism; D014161:Transduction, Genetic; D019065:Virus Assembly
chemical_list: D000956:Antigens, Viral; D000998:Antiviral Agents; D036022:Capsid Proteins; D019913:Nuclear Localization Signals; D020126:Brefeldin A; D000626:Aminopeptidases; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases; C048001:tripeptidyl-peptidase 2; D012697:Serine Endopeptidases; D046988:Proteasome Endopeptidase Complex