Applying Flow Virometry to Study the HIV Envelope Glycoprotein and Differences Across HIV Model Systems
Jonathan Burnie,
Claire Fernandes,
Ayushi Patel,
Arvin Tejnarine Persaud,
Deepa Chaphekar,
Danlan Wei,
Timothy Kit Hin Lee,
Vera A. Tang,
Claudia Cicala,
James Arthos,
Christina Guzzo
Affiliations
Jonathan Burnie
Department of Biological Sciences, University of Toronto Scarborough, Toronto, ON M1C 1A4, Canada
Claire Fernandes
Department of Biological Sciences, University of Toronto Scarborough, Toronto, ON M1C 1A4, Canada
Ayushi Patel
Department of Biological Sciences, University of Toronto Scarborough, Toronto, ON M1C 1A4, Canada
Arvin Tejnarine Persaud
Department of Biological Sciences, University of Toronto Scarborough, Toronto, ON M1C 1A4, Canada
Deepa Chaphekar
Department of Biological Sciences, University of Toronto Scarborough, Toronto, ON M1C 1A4, Canada
Danlan Wei
Laboratory of Immunoregulation, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
Timothy Kit Hin Lee
Department of Biological Sciences, University of Toronto Scarborough, Toronto, ON M1C 1A4, Canada
Vera A. Tang
Flow Cytometry and Virometry Core Facility, Department of Biochemistry, Microbiology, and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
Claudia Cicala
Laboratory of Immunoregulation, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
James Arthos
Laboratory of Immunoregulation, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
Christina Guzzo
Department of Biological Sciences, University of Toronto Scarborough, Toronto, ON M1C 1A4, Canada
The HIV envelope glycoprotein (Env) is a trimeric protein that facilitates viral binding and fusion with target cells. As the sole viral protein on the HIV surface, Env is important both for immune responses to HIV and in vaccine designs. Targeting Env in clinical applications is challenging due to its heavy glycosylation, high genetic variability, conformational camouflage, and its low abundance on virions. Thus, there is a critical need to better understand this protein. Flow virometry (FV) is a useful methodology for phenotyping the virion surface in a high-throughput, single virion manner. To demonstrate the utility of FV to characterize Env, we stained HIV virions with a panel of 85 monoclonal antibodies targeting different regions of Env. A broad range of antibodies yielded robust staining of Env, with V3 antibodies showing the highest quantitative staining. A subset of antibodies tested in parallel on viruses produced in CD4+ T cell lines, HEK293T cells, and primary cells showed that the cellular model of virus production can impact Env detection. Finally, in addition to being able to highlight Env heterogeneity on virions, we show FV can sensitively detect differences in Env conformation when soluble CD4 is added to virions before staining.
