CROI 2016 Abstract eBook

Abstract Listing

Poster Abstracts

308 Systematic Analysis of Glycan Heterogeneity Guides Rational Design of HIV Immunogens Wen-Han Yu ; Monia Draghi; Claudia Arevalo; Peng Zhao; Douglas Lauffenburger; LanceWells; Galit Alter Ragon Inst of MGH, MIT, and Harvard, Cambridge, MA, USA

Background: Glycans account for more than half of the HIV envelope gp120 protein mass, thought originally to disguise virus from the host immune response and to drive viral evasion. However, mounting evidence suggests highly variable glycans are shown to be antigenic determinants in epitope recognition for many of the most potent broadly neutralizing antibodies (bNAbs). Thus, vaccine design approaches, which harness the antigenic nature of the envelope glycan to guide the vaccine-induced humoral immune response to the sites of vulnerability for effective neutralization, may significantly advance the field. Yet, efforts to exploit the natural antigenicity of the gp120 glycan shield have only shown limited success, because the focus was only on the proximal glycans directly impacting bNAb recognition, which is not enough to appreciate the complexity of global bNAb-glycan interactions. Methods: Here we conducted a unique approach to systematically and computationally deconvolute the complexity of the global HIV glycan shield heterogeneity and link this heterogeneity to differential bNAb recognition fingerprints. Moreover, we developed a de novo immunogen design programwhich integrated all systematic data as well as gp120 structure information to engineer gp120 improving the bNAb recognitions. Results: Mass spectrometry-based glycoproteomics defined glycan occupancy across the gp120 proteome isolated from 94 distinct HIV viral isolates. Remarkably, highly diverse glycan occupancy profiles were observed at most potential N-linked glycosylation sites, including sites known to be targeted by bNAbs. Using an unsupervised machine learning algorithm, unique bNAb-glycan binding interaction signatures were identified, directed by both agonistic and antagonistic glycans that cooperatively facilitate antibody recognition. Moreover, these signatures were utilized to design glycan-optimized immunogens, which were able to selectively improve or alter different bNAb recognitions. Conclusions: This approach provides a novel rational design strategy to improve HIV envelope antigenicity, particularly to glycan-dependent bNAbs, via selective glycosylation profiles tailored to enhance bNAb binding. 309LB Optimal Combinations of bnAbs for Prevention and Treatment of HIV-1 Clade C Infection Michael Seaman 1 ; KshitijWagh 2 ;Tanmoy Bhattacharya Bhattacharya 2 ; CarolynWilliamson 3 ; Alex Robles 4 ; Madeleine Bayne 4 ; Jetta Garrity 4 ; Michael Rist 4 ; David Montefiori 5 ; Bette Korber 2 1 Harvard Med School, Boston, MA, USA; 2 Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM, USA; 3 Univ of Cape Town and National Hlth Laboratory Service, Cape Town, South Africa; 4 Beth Israel Deaconess Med Cntr, Boston, MA, USA; 5 Duke Univ, Durham, NC, USA Background: The identification of a new generation of potent broadly neutralizing HIV-1 antibodies (bnAbs) has generated substantial interest in their potential use for the prevention and/or treatment of HIV-1 infection. While combinations of bnAbs targeting distinct epitopes on the viral envelope (Env) will likely be required to overcome the extraordinary diversity of HIV-1, a key outstanding question is which bnAbs, and howmany, will be needed to achieve optimal clinical benefit. Methods: We assessed the neutralizing activity of 15 bnAbs targeting four distinct epitopes of Env, including the CD4-binding site (CD4bs), the V1/V2-glycan region, the V3-glycan region, and the gp41 membrane proximal external region (MPER), against a panel of 200 acute/early clade C HIV-1 Env pseudoviruses. A mathematical model was developed that predicted neutralization by a subset of experimentally evaluated bnAb combinations with high accuracy. Using this model, we performed a comprehensive and systematic comparison of the predicted neutralizing activity of over 1,600 possible double, triple, and quadruple bnAb combinations. Results: Best-in-class single bnAbs for potency and breadth were CAP256-VRC26.25 (V2-glycan), 10-1074V (V3-glycan), VRC07-523 (CD4bs) and 10E8 (MPER). Optimal bnAb combinations were identified based on breadth and potency of neutralization, as well as other relevant measures such as the extent of complete neutralization and instantaneous inhibitory potential. By these criteria, VRC07-523 + CAP256-VRC26.25, VRC07-523 + CAP256-VRC26.25 + 10-1074V and VRC07-523 + CAP256-VRC26.25 + 10-1074V + 10E8 were identified as the best 2, 3, and 4 bnAb combinations, respectively. Triple and quadruple combinations of bnAbs were significantly more effective than the best double combinations. Quadruple bnAb combinations were predicted to be similar to triple combinations by some metrics, and significantly better by others. Importantly, increasing the total number of bnAbs in combinations improved the probability of having multiple bnAbs simultaneously active against a given virus, a requirement that may be critical for countering escape in vivo . Conclusions: Combinations with higher numbers of bnAbs are advantageous in providing increased potency, breadth, complete neutralization, and active coverage against HIV-1 clade C. These results provide a rationale for advancing bnAb combinations with the best in vitro predictors of success into clinical trials for both the prevention and treatment of HIV-1 infection. 310LB Informatics-Based Improvement of HIV-1 Neutralizing Antibody 10E8 Peter D. Kwong 1 ;Young D. Kwon 2 ; Gwo-Yu Chuang 2 ; Baoshan Zhang 2 ;Tatyana Gindin 3 ; Krisha McKee 2 ; Sijy O’Dell 2 ; Mark Connors 4 ; Lawrence Shapiro 3 ; John R. Mascola 5 1 Vaccine Rsr Cntr, NIAID/NIH, Bethesda, MD, USA; 2 Vaccine Rsr Cntr, NIAID, NIH, Bethesda, MD, USA; 3 Columbia Univ, New York, NY, USA; 4 NIAID, NIH, Bethesda, MD, USA; 5 VRC, NIAID, NIH, Bethesda, MD, USA Background: Passive delivery of antibody may provide prophylaxis against and treatment of HIV-1. One antibody of potential promise is human antibody 10E8, which targets the membrane-proximal external region (MPER) and is capable of neutralizing ~98% of HIV-1 isolates. The extraordinary breadth of 10E8 is tempered, however, by its less-than- optimal solubility, which complicates manufacture, and the need to dose with large amounts antibody. Methods: We employed technologies that provide information-rich output including X-ray crystallography, next-generation sequencing and surface-matrix screening to improve 10E8 solubility and potency. Specifically, we combined a structure-based approach with natural variants obtained through sequencing of immunoglobulin transcripts from donor N152, the source of antibody 10E8. The surface-matrix approach involved the creation of hundreds of individual surface mutants, to probe the effect of hydrophobic protrusion (Phe or Trp), hydrophilic protrusion (Arg), large hydrophilic protrusion (N-linked glycan), and side-chain removal (poly-glycine). Solubility was assessed through measurements of turbidity, and potency was assessed through in vitro neutralization of virus panels: 9-isolates for screening and up to 200-isolates for detailed comparison. Results: By combining a structure-based approach with natural variation in potency and solubility from the 10E8 lineage, we created variants of 10E8, which retained the potency and extraordinary neutralization breadth of the parent 10E8. Of these, 10E8v4 with 26 changes versus the parent 10E8 was most soluble, with potency on a panel of 200-HIV-1 isolates similar to that of the parent 10E8 and half-life in rhesus macaques of ~10 days. Incorporation into 10E8v4 of select alterations from the surface-matrix approach yielded variants such as antibody 10E8v4-5R-100cF, with acceptable solubility, low poly-reactivity, and an IC80 potency of ~0.03 ug/ml, approximately 50-fold better than the parent 10E8. Conclusions: The application of information-rich technologies to antibody optimization allows for the enhancement of manufacturing characteristics and therapeutic properties. We propose that these technologies might serve as a general means to enhance the clinical utility of naturally occurring antibodies. The increased solubility and potency of the 10E8v4-5R-100cF variant opens the possibility for use of a MPER-directed specificity in prophylaxis or immunotherapy at a modest dose (1-10 mg/every 2-3 months per typical adult). 311LB Effect of Infusion of Broadly Neutralizing Antibody VRC01 on HIV Plasma Rebound Tae-Wook Chun 1 ; Michael Sneller 2 ; Catherine Seamon 1 ; Jesse S. Justement 1 ; Mary E. Petrone 1 ; Eric Refsland 1 ; Julie Ledgerwood 3 ; Katherine Clarridge 1 ; Susan Moir 1 ; Anthony S. Fauci 1 1 NIAID, NIH, Bethesda, MD, USA; 2 NIH, Bethesda, MD, USA; 3 VRC, NIAID, NIH, Bethesda, MD, USA Background: Recent advances in immunogen and antibody cloning technologies have led to the isolation of several highly potent and broadly neutralizing HIV-specific antibodies (bNAb) from B cells of infected individuals. Among these, VRC01 has proven to be effective in neutralizing diverse strains of HIV in vitro and in animal models and has the capacity

Poster Abstracts


CROI 2016

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