title: Structure-based Design of Cyclically Permuted HIV-1 gp120 Trimers That Elicit Neutralizing Antibodies.
abstract: A major goal for HIV-1 vaccine development is an ability to elicit strong and durable broadly neutralizing antibody (bNAb) responses. The trimeric envelope glycoprotein (Env) spikes on HIV-1 are known to contain multiple epitopes that are susceptible to bNAbs isolated from infected individuals. Nonetheless, all trimeric and monomeric Env immunogens designed to date have failed to elicit such antibodies. We report the structure-guided design of HIV-1 cyclically permuted gp120 that forms homogeneous, stable trimers, and displays enhanced binding to multiple bNAbs, including VRC01, VRC03, VRC-PG04, PGT128, and the quaternary epitope-specific bNAbs PGT145 and PGDM1400. Constructs that were cyclically permuted in the V1 loop region and contained an N-terminal trimerization domain to stabilize V1V2-mediated quaternary interactions, showed the highest homogeneity and the best antigenic characteristics. In guinea pigs, a DNA prime-protein boost regimen with these new gp120 trimer immunogens elicited potent neutralizing antibody responses against highly sensitive Tier 1A isolates and weaker neutralizing antibody responses with an average titer of about 115 against a panel of heterologous Tier 2 isolates. A modest fraction of the Tier 2 virus neutralizing activity appeared to target the CD4 binding site on gp120. These results suggest that cyclically permuted HIV-1 gp120 trimers represent a viable platform in which further modifications may be made to eventually achieve protective bNAb responses.
authors.affiliation: From the Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560 012, India.
authors.forename: Sannula
authors.initials: S
authors.lastname: Kesavardhana
authors.affiliation: From the Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560 012, India.
authors.forename: Raksha
authors.initials: R
authors.lastname: Das
authors.affiliation: Merck & Company, Inc., West Point, Pennsylvania 19486, and.
authors.forename: Michael
authors.initials: M
authors.lastname: Citron
authors.affiliation: From the Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560 012, India.
authors.forename: Rohini
authors.initials: R
authors.lastname: Datta
authors.affiliation: Merck & Company, Inc., West Point, Pennsylvania 19486, and.
authors.forename: Linda
authors.initials: L
authors.lastname: Ecto
authors.affiliation: From the Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560 012, India.
authors.forename: Nonavinakere Seetharam
authors.initials: NS
authors.lastname: Srilatha
authors.affiliation: Merck & Company, Inc., West Point, Pennsylvania 19486, and.
authors.forename: Daniel
authors.initials: D
authors.lastname: DiStefano
authors.affiliation: Merck & Company, Inc., West Point, Pennsylvania 19486, and.
authors.forename: Ryan
authors.initials: R
authors.lastname: Swoyer
authors.affiliation: Merck & Company, Inc., West Point, Pennsylvania 19486, and.
authors.forename: Joseph G
authors.initials: JG
authors.lastname: Joyce
authors.affiliation: From the Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560 012, India.
authors.forename: Somnath
authors.initials: S
authors.lastname: Dutta
authors.affiliation: the Department of Surgery, Duke University, Durham, North Carolina 27705.
authors.forename: Celia C
authors.initials: CC
authors.lastname: LaBranche
authors.affiliation: the Department of Surgery, Duke University, Durham, North Carolina 27705.
authors.forename: David C
authors.initials: DC
authors.lastname: Montefiori
authors.affiliation: Merck & Company, Inc., West Point, Pennsylvania 19486, and jessica_flynn@merck.com.
authors.forename: Jessica A
authors.initials: JA
authors.lastname: Flynn
authors.affiliation: From the Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560 012, India, varadar@mbu.iisc.ernet.in.
authors.forename: Raghavan
authors.initials: R
authors.lastname: Varadarajan
mesh_terms: D000818:Animals; D057134:Antibodies, Neutralizing / Q000097:blood* / Q000276:immunology; D001665:Binding Sites; D018360:Crystallography, X-Ray; D015195:Drug Design; D000939:Epitopes / Q000276:immunology; D006168:Guinea Pigs; D015483:HIV Antibodies / Q000097:blood* / Q000276:immunology; D015699:HIV Envelope Protein gp120 / Q000276:immunology* / Q000378:metabolism*; D015658:HIV Infections / Q000097:blood / Q000276:immunology* / Q000821:virology; D015497:HIV-1 / Q000276:immunology*; D006801:Humans; D011485:Protein Binding; D011487:Protein Conformation; D055503:Protein Multimerization
chemical_list: D057134:Antibodies, Neutralizing; D000939:Epitopes; D015483:HIV Antibodies; D015699:HIV Envelope Protein gp120
keywords: CD4 binding site; Env trimers; cyclic permutation; human immunodeficiency virus (HIV); immunogen design; immunogenicity; protein conformation; protein engineering; protein stability; protein stabilization, dynamics