Adeno-Associated Virus (AAV) Capsid Stability and Liposome Remodeling During Endo/Lysosomal pH Trafficking
Bridget Lins-Austin,
Saajan Patel,
Mario Mietzsch,
Dewey Brooke,
Antonette Bennett,
Balasubramanian Venkatakrishnan,
Kim Van Vliet,
Adam N. Smith,
Joanna R. Long,
Robert McKenna,
Mark Potter,
Barry Byrne,
Sanford L. Boye,
Brian Bothner,
Regine Heilbronn,
Mavis Agbandje-McKenna
Affiliations
Bridget Lins-Austin
Department of Biochemistry and Molecular Biology, Center for Structural Biology, McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL 32610, USA
Saajan Patel
Department of Biochemistry and Molecular Biology, Center for Structural Biology, McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL 32610, USA
Mario Mietzsch
Department of Biochemistry and Molecular Biology, Center for Structural Biology, McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL 32610, USA
Dewey Brooke
Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT 59717, USA
Antonette Bennett
Department of Biochemistry and Molecular Biology, Center for Structural Biology, McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL 32610, USA
Balasubramanian Venkatakrishnan
Department of Biochemistry and Molecular Biology, Center for Structural Biology, McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL 32610, USA
Kim Van Vliet
Department of Biochemistry and Molecular Biology, Center for Structural Biology, McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL 32610, USA
Adam N. Smith
Department of Chemistry, College of Liberal Arts & Sciences, University of Florida, Gainesville, FL 32611, USA
Joanna R. Long
Department of Biochemistry and Molecular Biology, Center for Structural Biology, McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL 32610, USA
Robert McKenna
Department of Biochemistry and Molecular Biology, Center for Structural Biology, McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL 32610, USA
Mark Potter
Powell Gene Therapy Center Vector Core, University of Florida, Gainesville, FL 32610, USA
Barry Byrne
Powell Gene Therapy Center Vector Core, University of Florida, Gainesville, FL 32610, USA
Sanford L. Boye
Powell Gene Therapy Center Vector Core, University of Florida, Gainesville, FL 32610, USA
Brian Bothner
Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT 59717, USA
Regine Heilbronn
Institute of Virology, Charité Medical School, 12203 Berlin, Germany
Mavis Agbandje-McKenna
Department of Biochemistry and Molecular Biology, Center for Structural Biology, McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL 32610, USA
Adeno-associated viruses (AAVs) are small, non-pathogenic ssDNA viruses being used as therapeutic gene delivery vectors for the treatment of a variety of monogenic diseases. An obstacle to successful gene delivery is inefficient capsid trafficking through the endo/lysosomal pathway. This study aimed to characterize the AAV capsid stability and dynamics associated with this process for a select number of AAV serotypes, AAV1, AAV2, AAV5, and AAV8, at pHs representative of the early and late endosome, and the lysosome (6.0, 5.5, and 4.0, respectively). All AAV serotypes displayed thermal melt temperatures that varied with pH. The stability of AAV1, AAV2, and AAV8 increased in response to acidic conditions and then decreased at pH 4.0. In contrast, AAV5 demonstrated a consistent decrease in thermostability in response to acidification. Negative-stain EM visualization of liposomes in the presence of capsids at pH 5.5 or when heat shocked showed induced remodeling consistent with the externalization of the PLA2 domain of VP1u. These observations provide clues to the AAV capsid dynamics that facilitate successful infection. Finally, transduction assays revealed a pH and temperature dependence with low acidity and temperatures > 4 °C as detrimental factors.
