title: Heparin binding directs activation of T cells against adeno-associated virus serotype 2 capsid.
abstract: Activation of T cells to the capsid of adeno-associated virus (AAV) serotype 2 vectors has been implicated in liver toxicity in a recent human gene therapy trial of hemophilia B. To further investigate this kind of toxicity, we evaluated T-cell responses to AAV capsids after intramuscular injection of vectors into mice and nonhuman primates. High levels of T cells specific to capsids of vectors based on AAV2 and a phylogenetically related AAV variant were detected. Vectors from other AAV clades such as AAV8 (ref. 3), however, did not lead to activation of capsid-specific T cells. Through the generation of AAV2-AAV8 hybrids and the creation of site-directed mutations, we mapped the domain that directs the activation of T cells to the RXXR motif on VP3, which was previously shown to confer binding of the virion to heparan sulfate proteoglycan (HSPG). Evaluation of natural and engineered AAV variants showed direct correlations between heparin binding, uptake into human dendritic cells (DCs) and activation of capsid-specific T cells. The role of heparin binding in the activation of CD8(+) T cells may be useful in modulating the immunogenicity of antigens and improving the safety profile of existing AAV vectors for gene therapy.
authors.affiliation: Gene Therapy Program, Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, 125 S. 31st Street, Philadelphia, Pennsylvania 19104, USA.
authors.forename: Luk H
authors.initials: LH
authors.lastname: Vandenberghe
authors.forename: Lili
authors.initials: L
authors.lastname: Wang
authors.forename: Suryanarayan
authors.initials: S
authors.lastname: Somanathan
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhi
authors.forename: Joanita
authors.initials: J
authors.lastname: Figueredo
authors.forename: Roberto
authors.initials: R
authors.lastname: Calcedo
authors.forename: Julio
authors.initials: J
authors.lastname: Sanmiguel
authors.forename: Ravi A
authors.initials: RA
authors.lastname: Desai
authors.forename: Christopher S
authors.initials: CS
authors.lastname: Chen
authors.forename: Julie
authors.initials: J
authors.lastname: Johnston
authors.forename: Rebecca L
authors.initials: RL
authors.lastname: Grant
authors.forename: Guangping
authors.initials: G
authors.lastname: Gao
authors.forename: James M
authors.initials: JM
authors.lastname: Wilson
mesh_terms: D000818:Animals; D016466:CHO Cells; D002213:Capsid / Q000378:metabolism*; D036022:Capsid Proteins / Q000737:chemistry / Q000378:metabolism; D006224:Cricetinae; D003713:Dendritic Cells / Q000378:metabolism; D000229:Dependovirus / Q000145:classification / Q000235:genetics* / Q000378:metabolism; D005819:Genetic Markers; D005822:Genetic Vectors / Q000008:administration & dosage; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology; D006367:HeLa Cells; D006493:Heparin / Q000378:metabolism* / Q000494:pharmacology; D006801:Humans; D007371:Interferon-gamma / Q000032:analysis / Q000276:immunology; D015847:Interleukin-4 / Q000494:pharmacology; D007700:Kinetics; D007963:Leukocytes, Mononuclear / Q000378:metabolism; D008213:Lymphocyte Activation / Q000187:drug effects; D008252:Macaca fascicularis; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D017434:Protein Structure, Tertiary; D012703:Serotyping; D013601:T-Lymphocytes / Q000378:metabolism*; D013997:Time Factors
chemical_list: D036022:Capsid Proteins; D005819:Genetic Markers; D015847:Interleukin-4; D007371:Interferon-gamma; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D006493:Heparin