title: Well-ordered trimeric HIV-1 subtype B and C soluble spike mimetics generated by negative selection display native-like properties.
abstract: The structure of BG505 gp140 SOSIP, a soluble mimic of the native HIV-1 envelope glycoprotein (Env), marks the beginning of new era in Env structure-based immunogen design. Displaying a well-ordered quaternary structure, these subtype A-derived trimers display an excellent antigenic profile, discriminating recognition by broadly neutralizing antibodies (bNAbs) from non-broadly neutralizing antibodies (non-bNAbs), and provide a solid Env-based immunogenic platform starting point. Even with this important advance, obtaining homogeneous well-ordered soluble SOSIP trimers derived from other subtypes remains challenging. Here, we report the "rescue" of homogeneous well-ordered subtype B and C SOSIP trimers from a heterogeneous Env mixture using CD4 binding site-directed (CD4bs) non-bNAbs in a negative-selection purification process. These non-bNAbs recognize the primary receptor CD4bs only on disordered trimers but not on the native Env spike or well-ordered soluble trimers due to steric hindrance. Following negative selection to remove disordered oligomers, we demonstrated recovery of well-ordered, homogeneous trimers by electron microscopy (EM). We obtained 3D EM reconstructions of unliganded trimers, as well as in complex with sCD4, a panel of CD4bs-directed bNAbs, and the cleavage-dependent, trimer-specific bNAb, PGT151. Using bio-layer light interferometry (BLI) we demonstrated that the well-ordered trimers were efficiently recognized by bNAbs and poorly recognized by non-bNAbs, representing soluble mimics of the native viral spike. Biophysical characterization was consistent with the thermostability of a homogeneous species that could be further stabilized by specific bNAbs. This study revealed that Env trimers generate different frequencies of well-ordered versus disordered aberrant trimers even when they are genetically identical. By negatively selecting the native-like well-ordered trimers, we establish a new means to obtain soluble Env mimetics derived from subtypes B and C for expanded use as candidate vaccine immunogens.
authors.affiliation: IAVI Neutralizing Antibody Center at The Scripps Research Institute, La Jolla, California, United States of America.
authors.forename: Javier
authors.initials: J
authors.lastname: Guenaga
authors.affiliation: Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, California, United States of America; Center for HIV/AIDS Vaccine Immunology and Immunogen Discovery, The Scripps Research Institute, La Jolla, California, United States of America.
authors.forename: Natalia
authors.initials: N
authors.lastname: de Val
authors.affiliation: IAVI Neutralizing Antibody Center at The Scripps Research Institute, La Jolla, California, United States of America.
authors.forename: Karen
authors.initials: K
authors.lastname: Tran
authors.affiliation: IAVI Neutralizing Antibody Center at The Scripps Research Institute, La Jolla, California, United States of America.
authors.forename: Yu
authors.initials: Y
authors.lastname: Feng
authors.affiliation: IAVI Neutralizing Antibody Center at The Scripps Research Institute, La Jolla, California, United States of America.
authors.forename: Karen
authors.initials: K
authors.lastname: Satchwell
authors.affiliation: IAVI Neutralizing Antibody Center at The Scripps Research Institute, La Jolla, California, United States of America; Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, California, United States of America; Center for HIV/AIDS Vaccine Immunology and Immunogen Discovery, The Scripps Research Institute, La Jolla, California, United States of America.
authors.forename: Andrew B
authors.initials: AB
authors.lastname: Ward
authors.affiliation: IAVI Neutralizing Antibody Center at The Scripps Research Institute, La Jolla, California, United States of America; Center for HIV/AIDS Vaccine Immunology and Immunogen Discovery, The Scripps Research Institute, La Jolla, California, United States of America; Department of Immunology and Microbial Science, The Scripps Research Institute, La Jolla, California, United States of America.
authors.forename: Richard T
authors.initials: RT
authors.lastname: Wyatt
mesh_terms: D016915:AIDS Vaccines / Q000302:isolation & purification / Q000378:metabolism; D057134:Antibodies, Neutralizing / Q000276:immunology; D000918:Antibody Specificity; D061505:Cell Surface Display Techniques / Q000379:methods*; D000939:Epitopes / Q000737:chemistry / Q000276:immunology* / Q000378:metabolism; D057809:HEK293 Cells; D015497:HIV-1 / Q000276:immunology*; D006801:Humans; D008958:Models, Molecular; D015202:Protein Engineering / Q000379:methods*; D017510:Protein Folding; D055503:Protein Multimerization / Q000276:immunology; D020836:Protein Structure, Quaternary; D011994:Recombinant Proteins / Q000737:chemistry / Q000276:immunology / Q000302:isolation & purification* / Q000378:metabolism; D054299:env Gene Products, Human Immunodeficiency Virus / Q000737:chemistry / Q000276:immunology / Q000302:isolation & purification* / Q000378:metabolism
chemical_list: D016915:AIDS Vaccines; D057134:Antibodies, Neutralizing; D000939:Epitopes; D011994:Recombinant Proteins; D054299:env Gene Products, Human Immunodeficiency Virus; C097729:gp140 envelope protein, Human immunodeficiency virus 1