The Assembly-Activating Protein Promotes Stability and Interactions between AAV’s Viral Proteins to Nucleate Capsid Assembly
Anna C. Maurer,
Simon Pacouret,
Ana Karla Cepeda Diaz,
Jessica Blake,
Eva Andres-Mateos,
Luk H. Vandenberghe
Affiliations
Anna C. Maurer
Grousbeck Gene Therapy Center, Schepens Eye Research Institute, Massachusetts Eye and Ear, Boston, MA 02114, USA; Ocular Genomics Institute, Department of Ophthalmology, Harvard Medical School, Boston, MA 02114, USA
Simon Pacouret
Grousbeck Gene Therapy Center, Schepens Eye Research Institute, Massachusetts Eye and Ear, Boston, MA 02114, USA; Ocular Genomics Institute, Department of Ophthalmology, Harvard Medical School, Boston, MA 02114, USA; INSERM UMR 1089, University of Nantes, Nantes University Hospital, 22 Boulevard Benoni Goullin, 44200 Nantes, France
Ana Karla Cepeda Diaz
Grousbeck Gene Therapy Center, Schepens Eye Research Institute, Massachusetts Eye and Ear, Boston, MA 02114, USA; Ocular Genomics Institute, Department of Ophthalmology, Harvard Medical School, Boston, MA 02114, USA
Jessica Blake
Grousbeck Gene Therapy Center, Schepens Eye Research Institute, Massachusetts Eye and Ear, Boston, MA 02114, USA; Ocular Genomics Institute, Department of Ophthalmology, Harvard Medical School, Boston, MA 02114, USA
Eva Andres-Mateos
Grousbeck Gene Therapy Center, Schepens Eye Research Institute, Massachusetts Eye and Ear, Boston, MA 02114, USA; Ocular Genomics Institute, Department of Ophthalmology, Harvard Medical School, Boston, MA 02114, USA
Luk H. Vandenberghe
Grousbeck Gene Therapy Center, Schepens Eye Research Institute, Massachusetts Eye and Ear, Boston, MA 02114, USA; Ocular Genomics Institute, Department of Ophthalmology, Harvard Medical School, Boston, MA 02114, USA; Harvard Stem Cell Institute, Harvard University, Cambridge, MA 02138, USA; The Broad Institute of Harvard and MIT, Cambridge, MA 02142, USA; Corresponding author
Summary: The adeno-associated virus (AAV) vector is a preferred delivery platform for in vivo gene therapy. Natural and engineered variations of the AAV capsid affect a plurality of phenotypes relevant to gene therapy, including vector production and host tropism. Fundamental to these aspects is the mechanism of AAV capsid assembly. Here, the role of the viral co-factor assembly-activating protein (AAP) was evaluated in 12 naturally occurring AAVs and 9 putative ancestral capsid intermediates. The results demonstrate increased capsid protein stability and VP-VP interactions in the presence of AAP. The capsid’s dependence on AAP can be partly overcome by strengthening interactions between monomers within the assembly, as illustrated by the transfer of a minimal motif defined by a phenotype-to-phylogeny mapping method. These findings suggest that the emergence of AAP within the Dependovirus genus relaxes structural constraints on AAV assembly in favor of increasing the degrees of freedom for the capsid to evolve. : Maurer et al. describe a phenotype-to-phylogeny mapping strategy correlating phenotypic variation in AAVs to a reconstructed phylogeny, revealing capsid structure-function relationships relevant to that phenotype. Dependence on the viral co-factor AAP for capsid assembly is examined, and capsid functional motifs, in addition to mechanistic roles of AAP, are elucidated. Keywords: AAV, AAP, adeno-associated virus, capsid assembly, manufacturing, capsid, vector engineering, structure-function, gene therapy
