title: Characterization of the relationship of AAV capsid domain swapping to liver transduction efficiency.
abstract: Recombinant adeno-associated virus (AAV) vectors show promise for use in gene therapy. For liver-targeted gene transfer in animals, AAV vectors pseudotyped with the AAV serotype 8 (AAV8) capsid have definite advantages over the widely used but less efficient serotype AAV2, even though the capsid amino acid sequences are 82% conserved. To demonstrate the mechanism behind the higher liver transduction efficiency associated with AAV8 capsids, we adopted a domain-swapping strategy that would generate 27 chimeric capsid genes containing exchanged domains between AAV2 and AAV8. The resulting chimeric capsids were then used to package AAV genomes with a liver-specific human coagulation factor IX (hFIX) expression cassette. By comparing the transduction efficiencies between vectors pseudotyped with chimeric, AAV2 and AAV8 capsids, we found that the more efficient liver transduction achieved by AAV8 was closely related to the components of its interstrand Loop IV domain, particularly the subloops 1 and 4. These subloops are exposed on opposite sides of a threefold proximal peak on the virion surface, which may function as a critical structural determinant for AAV transduction. Because a single specific peptide component could not explain all the observed differences in the transduction parameters, we suggest that important subloop regions require interaction with other portions of the capsid for their functioning.
authors.affiliation: Department of Pediatrics, Stanford University, Stanford, California 94305, USA.
authors.forename: Xuan
authors.initials: X
authors.lastname: Shen
authors.forename: Terry
authors.initials: T
authors.lastname: Storm
authors.forename: Mark A
authors.initials: MA
authors.lastname: Kay
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002213:Capsid / Q000378:metabolism*; D036022:Capsid Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D002460:Cell Line; D000229:Dependovirus / Q000737:chemistry / Q000502:physiology*; D005165:Factor V / Q000235:genetics / Q000378:metabolism; D005260:Female; D015870:Gene Expression; D005822:Genetic Vectors / Q000235:genetics; D016679:Genome, Viral / Q000235:genetics; D006801:Humans; D008099:Liver / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D008958:Models, Molecular; D008969:Molecular Sequence Data; D020836:Protein Structure, Quaternary; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014161:Transduction, Genetic / Q000379:methods*; D019076:Transgenes / Q000235:genetics
chemical_list: D036022:Capsid Proteins; D011994:Recombinant Proteins; D005165:Factor V