Antigenic characterization of the human immunodeficiency virus (HIV-1) envelope glycoprotein precursor incorporated into nanodiscs.
The entry of human immunodeficiency virus (HIV-1) into host cells is mediated by the viral envelope glycoproteins (Envs), which are derived by the proteolytic cleavage of a trimeric gp160 Env precursor. The mature Env trimer is a major target for entry inhibitors and vaccine-induced neutralizing antibodies. Env interstrain variability, conformational flexibility and heavy glycosylation contribute to evasion of the host immune response, and create challenges for structural characterization and vaccine development. Here we investigate variables associated with reconstitution of the HIV-1 Env precursor into nanodiscs, nanoscale lipid bilayer discs enclosed by membrane scaffolding proteins. We identified detergents, as well as lipids similar in composition to the viral lipidome, that allowed efficient formation of Env-nanodiscs (Env-NDs). Env-NDs were created with the full-length Env precursor and with an Env precursor with the majority of the cytoplasmic tail intact. The self-association of Env-NDs was decreased by glutaraldehyde crosslinking. The Env-NDs exhibited an antigenic profile expected for the HIV-1 Env precursor. Env-NDs were recognized by broadly neutralizing antibodies. Of note, neutralizing antibody epitopes in the gp41 membrane-proximal external region and in the gp120:gp41 interface were well exposed on Env-NDs compared with Env expressed on cell surfaces. Most Env epitopes recognized by non-neutralizing antibodies were masked on the Env-NDs. This antigenic profile was stable for several days, exhibiting a considerably longer half-life than that of Env solubilized in detergents. Negative selection with weak neutralizing antibodies could be used to improve the antigenic profile of the Env-NDs. Finally, we show that lipid adjuvants can be incorporated into Env-NDs. These results indicate that Env-NDs represent a potentially useful platform for investigating the structural, functional and antigenic properties of the HIV-1 Env trimer in a membrane context.
Department of Cancer Immunology & Virology, Dana-Farber Cancer Institute, Department of Microbiology & Immunobiology, Harvard Medical School, Boston, MA, United States of America.
Kristen C
KC
Witt
Department of Cancer Immunology & Virology, Dana-Farber Cancer Institute, Department of Microbiology & Immunobiology, Harvard Medical School, Boston, MA, United States of America.
Luis
L
Castillo-Menendez
Departments of Medicine, University of Alabama at Birmingham, Birmingham, AL, United States of America.
Haitao
H
Ding
Department of Cancer Immunology & Virology, Dana-Farber Cancer Institute, Department of Microbiology & Immunobiology, Harvard Medical School, Boston, MA, United States of America.
Nicole
N
Espy
Department of Cancer Immunology & Virology, Dana-Farber Cancer Institute, Department of Microbiology & Immunobiology, Harvard Medical School, Boston, MA, United States of America.
Shijian
S
Zhang
Departments of Medicine, University of Alabama at Birmingham, Birmingham, AL, United States of America.|Birmingham Veterans Affairs Medical Center, Research Service, Birmingham, AL, United States of America.
John C
JC
Kappes
Department of Cancer Immunology & Virology, Dana-Farber Cancer Institute, Department of Microbiology & Immunobiology, Harvard Medical School, Boston, MA, United States of America.|Department of Immunology & Infectious Diseases, Harvard School of Public Health, Boston, MA, United States of America.
Joseph
J
Sodroski
D000818:Animals; D016466:CHO Cells; D002460:Cell Line; D003412:Cricetulus; D000939:Epitopes / Q000276:immunology; D015483:HIV Antibodies / Q000276:immunology*; D015699:HIV Envelope Protein gp120 / Q000378:metabolism*; D019302:HIV Envelope Protein gp160 / Q000378:metabolism*; D015700:HIV Envelope Protein gp41 / Q000378:metabolism*; D015497:HIV-1 / Q000276:immunology*; D006801:Humans; D008051:Lipid Bilayers / Q000276:immunology* / Q000378:metabolism; D049329:Nanostructures; D053586:Virus Internalization
D000939:Epitopes; D015483:HIV Antibodies; D015699:HIV Envelope Protein gp120; D019302:HIV Envelope Protein gp160; D015700:HIV Envelope Protein gp41; D008051:Lipid Bilayers