Well-ordered trimeric HIV-1 subtype B and C soluble spike mimetics generated by negative selection display native-like properties

PLoS Pathog. 2015 Jan 8;11(1):e1004570. doi: 10.1371/journal.ppat.1004570. eCollection 2015 Jan.

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.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • AIDS Vaccines / isolation & purification
  • AIDS Vaccines / metabolism
  • Antibodies, Neutralizing / immunology
  • Antibody Specificity
  • Cell Surface Display Techniques / methods*
  • Epitopes / chemistry
  • Epitopes / immunology*
  • Epitopes / metabolism
  • HEK293 Cells
  • HIV-1 / immunology*
  • Humans
  • Models, Molecular
  • Protein Engineering / methods*
  • Protein Folding
  • Protein Multimerization / immunology
  • Protein Structure, Quaternary
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / immunology
  • Recombinant Proteins / isolation & purification*
  • Recombinant Proteins / metabolism
  • env Gene Products, Human Immunodeficiency Virus / chemistry
  • env Gene Products, Human Immunodeficiency Virus / immunology
  • env Gene Products, Human Immunodeficiency Virus / isolation & purification*
  • env Gene Products, Human Immunodeficiency Virus / metabolism

Substances

  • AIDS Vaccines
  • Antibodies, Neutralizing
  • Epitopes
  • Recombinant Proteins
  • env Gene Products, Human Immunodeficiency Virus
  • gp140 envelope protein, Human immunodeficiency virus 1