Structural characterization of an envelope-associated adeno-associated virus type 2 capsid

Joshua A Hull; Mario Mietzsch; Paul Chipman; David Strugatsky; Robert McKenna

doi:10.1016/j.virol.2021.09.010

Structural characterization of an envelope-associated adeno-associated virus type 2 capsid

Virology. 2022 Jan 2:565:22-28. doi: 10.1016/j.virol.2021.09.010. Epub 2021 Oct 6.

Authors

Joshua A Hull¹, Mario Mietzsch¹, Paul Chipman¹, David Strugatsky², Robert McKenna³

Affiliations

¹ Department of Biochemistry and Molecular Biology, College of Medicine, Center for Structural Biology, McKnight Brain Institute, University of Florida, Gainesville, FL, 32610-0245, USA.
² California NanoSystems Institute, University of California, Los Angeles, Los Angeles, CA, 90095, USA; Department of Microbiology, Immunology & Molecular Genetics, University of California, Los Angeles, Los Angeles, CA, 90095, USA.
³ Department of Biochemistry and Molecular Biology, College of Medicine, Center for Structural Biology, McKnight Brain Institute, University of Florida, Gainesville, FL, 32610-0245, USA. Electronic address: rmckenna@ufl.edu.

Abstract

Adeno-associated virus (AAV) are classified as non-enveloped ssDNA viruses. However, AAV capsids embedded within exosomes have been observed, and it has been suggested that the AAV membrane associated accessory protein (MAAP) may play a role in envelope-associated AAV (EA-AAV) capsid formation. Here, we observed and selected sufficient homogeneous EA-AAV capsids of AAV2, produced using the Sf9 baculoviral expression system, to determine the cryo-electron microscopy (cryo-EM) structure at 3.14 Å resolution. The reconstructed map confirmed that the EA-AAV capsid, showed no significant structural variation compared to the non-envelope capsid. In addition, the Sf9 expression system used implies the notion that MAAP may enhance exosome AAV encapsulation. Furthermore, we speculate that these EA-AAV capsids may have therapeutic benefits over the currently used non-envelope AAV capsids, with advantages in immune evasion and/or improved infectivity.

Keywords: EA-AAV capsid; Enveloped-AAV; Exo-AAV; Gene therapy; MAAP; Sf9 production; Structure.

Publication types

Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't

MeSH terms

Animals
Capsid / chemistry
Capsid / ultrastructure*
Capsid Proteins / chemistry
Capsid Proteins / ultrastructure*
Cryoelectron Microscopy
Dependovirus / chemistry
Dependovirus / ultrastructure*
Exosomes
Immune Evasion
Protein Conformation
Sf9 Cells

Substances

Capsid Proteins

Supplementary concepts

Adeno-associated virus-2

Grants and funding

R01 GM082946/GM/NIGMS NIH HHS/United States