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

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

Author information

1
IAVI Neutralizing Antibody Center at The Scripps Research Institute, La Jolla, California, United States of America.
2
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.
3
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.
4
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.

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.

PMID:
25569572
PMCID:
PMC4287557
DOI:
10.1371/journal.ppat.1004570
[Indexed for MEDLINE]
Free PMC Article

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