Montefiori: Antibody Vaccine Immune Monitoring Consortium
The goal of the Comprehensive Antibody Vaccine Immune Monitoring Consortium (CAVIMC) is to facilitate the discovery and eventual licensure of a safe, effective and practical HIV-1 vaccine for the world. The CAVIMC aims to accomplish this by using valid laboratory criteria and Good Clinical Laboratory Practices (GCLP) to monitor antibody responses in the systemic and mucosal compartment in preclinical and clinical phases of vaccine testing. We also aim to identify correlates of protective immunity and to generate new scientific findings that will help bridge the gap between preclinical vaccine discovery and human clinical trials.
1. Maintain an effective Operations and Administrative Core that oversees the activities and finances of the CAVIMC, and serves as a liaison to CAVD investigators and the Gates Foundation.
2. Maintain a Central Reference Laboratory for assay validation, training and proficiency testing aimed at harmonizing the types of assays and standard operating procedures (SOPs) used between laboratories.
3. Maintain a network of Core Assay Laboratories that assess a variety of HIV- and SIV-specific antibodies.
4. Maintain a network of Molecular Virology Laboratories to clone and sequence env genes and to assess genetic diversity as it relates to key antigenic determinants and vaccine efficacy.
5. Maintain capacity to perform analytical and computational biology with a focus on antibody determinants of Env antigenicity and immunogenicity.
6. Maintain an effective Central Quality Assurance Unit (CQAU) that oversees all GCLP-compliant laboratories in the CAVIMC and implements competency and proficiency testing programs.
7. Develop an Antigen Reagent Program to create a stable supply of a well-characterized, multi-clade panel of HIV-1 envelope glycoprotein antigens as gp120 and oligomeric gp140 proteins, gp70-V1/V2 scaffolds, V2 and C1 RV144 “hotspot” peptides and peptide arrays, for use in assessing vaccine-elicited antibodies as they relate to the correlates in RV144 and future efficacy trials.
8. Identify correlates of protective immunity.
9. Provide new scientific findings that will help bridge the gap between preclinical vaccine discovery and human clinical trials.
· The CAVIMC offers highly standardized and validated assays for binding antibodies and neutralizing antibodies with high throughput capacity and GCLP compliance. We have capacity to measure total Env-specific IgG, IgG1, IgG2, IgG3, IgG4, IgA and IgM in the systemic and mucosal compartments. Binding may be assessed in terms of magnitude, breadth and avidity (G. Tomaras & M. Alam). Neutralizing antibodies are assessed in multiple cell types (e.g., TZM-bl and A3R5) using Env-pseudotyped viruses, Env.IMC.LucR viruses and uncloned viruses of HIV, SIV and SHIV (D. Montefiori & M. Seaman).
· A qualified, automated TZM-bl assay (96-well and 384-well formats) is available at NVITAL VRC for high throughput characterization of monoclonal antibodies (J. Mascola & R. Bailer).
· Validation of the neutralization assay in A3R5 cells is complete in the Duke Central Reference Laboratory & Neutralizing Antibody Core 1 (D. Montefiori), in collaboration with EQAPOL and under the direction of the CAVIMC Central Quality Assurance Unit (M. Sarzotti-Kelsoe), with plans for formal implementation at the CAVIMC Neutralizing Antibody Core 2 (M. Seaman).
· Increased capacity for assessing antiviral antibody effector functions that include antibody-dependent cellular cytotoxicity (ADCC) in a GCLP compliant environment (G. Ferrari).
· A strong Central Quality Assurance Unit oversees all GCLP laboratories (M. Sarzotti-Kelsoe).
· An Epitope Mapping Core is fully operational and continues to develop technologies to map the epitopes of broadly neutralizing antibodies for CAVD studies. These technologies include epitope-engrafted HIV-2 (V1/V2, V3, MPER), chimeric and site-directed mutant Envs, peptide competition, serum fractionation (wild type and mutant Envs), native page for trimer binding of wild type and mutant Envs, and CD4-inducible epitopes (L. Morris).
· Increased capacity for utilization of an overlapping peptide microarray technology in collaboration with JPT Peptide Technologies, Inc, with peptides covering the entire gp160 of consensus clade A, B, C, D, AE, AG Envs, and Con-M Env and including HIV vaccine strains (1086C, TV1, ZM651, TH023, MN, CM244) as well as SIV for many CAVD studies.
· Ongoing analytical and computational analyses of the Neutralization Serotype Discovery Project (NSDP) resulted in a data-driven Global Virus Reference Panel (n=12 Env-pseudotyped viruses) that predicts neutralization response to the larger NSDP virus panel (CAVD VISC & B. Korber and team). This panel will be useful for developing immunogenicity endpoints that capture magnitude and breadth of neutralization to circulating strains in HIV-1 clinical trials. This global virus reference panel will be advantageous for cross vaccine trial comparisons and for predicting a clade specific response against specific viral populations (manuscript under revision with J. Virol.). The Global Virus Reference Panel will be augmented by new T/F clade C Env-pseudotyped viruses as described below (Southern Africa Clade C Virus Panel Project).
· In addition to the Global Virus Reference Panel, the NSDP team has a manuscript in AIDS which shows that most people appear to be capable of making low to moderate titers of broadly neutralizing antibodies. This study helps define the spectrum of serum neutralizing activity induced by HIV-1 infection and that should be possible to elicit with vaccines (Hraber et al., 2013, AIDS, In Press). Moreover, a primary manuscript discussing other major findings of the NSDP is in preparation.
· Analysis of peptide microarray data from the NSDP and three HIV-1 vaccine efficacy trials (Vax003, Vax004, RV144) provided a comprehensive catalogue of linear B cell epitopes in gp160 and revealed antibodies to linear epitopes in the V2 and V3 regions of gp120 significantly correlate with a lower risk of infection in RV144 (Gottardo et al., 2013, PLoS One, 8(9): e75665).
· The Southern Africa Clade C Virus Panel Project aims to obtain and characterize functional Env clones from approximately 200 acute infections in southern Africa, with an emphasis on transmitted/founder viruses and broad geographic diversity in preparation for planned phase 2b trials. Phase I of the project, which included the cloning of 200 functional T/F Env clones and characterization of the neutralization profile as Env-pseudotyped viruses, is complete. Phase II of the project whereby these Env-pseudotyped viruses will be tested against a large panel of sera from clade C, chronically infected individuals from various geographic regions in S. Africa is underway. The goal of phase II includes down selection of an optimal virus panel which is more recent in the epidemic for measuring antibody responses in future human clinical trials in S. Africa (C. Williamson, M. Seaman, L. Morris).
· The CAVIMC Molecular Virology Core (MVC) at UAB (C. Ochsenbauer) continues to expand a multi-clade panel of Env.IMC.LucR viruses and IMC viruses for both HIV-1 and SIV for use in neutralizing antibody and ADCC assays. A new initiative is in progress to define the tier phenotype of over 100 Env.IMC.LucR viruses in A3R5 cells in collaboration with the CAVIMC CQAU (M.Sarzotti-Kelsoe). The Core also developed Env.IMC.LucR constructs (both Env.ecto and Env.RE versions) of the Global Virus Reference Panel for use in A3R5 neutralization and ADCC assays. The Core also generates "special request" constructs for other CAVD investigators on a limited basis.
· The Antigen Reagent Program is divided into two phases with phase I nearly complete. Phase I included the production of a large panel of antigens in small quantity for extensive characterization by the CAVIMC Binding Ab Core (G. Tomaras & M. Alam) and down selection (CAVD VISC). In the coming months, Phase II will begin and include the large quantity production of the down selected antigens. The CAVIMC has partnered with the new CAVD Central Service Facility, the Protein Production Facility at Duke University (PI: B. Haynes) for the production of gp120 and gp140 proteins. Abe Pinter (UMDNJ) is producing the gp70-V1/V2 scaffolds and JPT Peptide Technologies, Inc. (Berlin, German) is producing the peptides and peptide arrays. Susan Zolla-Pazner (NYU) is producing a panel of monoclonal antibodies with known specificities which are being utilized in the characterization process.
· Substantial progress was made by the Fc Receptor-Mediated Antibody Effector Functions Working Group, including CAVD investigators (M. Ackerman, G. Alter, C. Love, J. Kappes, D. Forthal, G.Lewis, G. Ferrari and D. Montefiori), for the evaluation of a number of Fc-effector functional assays using centrally prepared sample sets with known differences in effector function. The ultimate goal of this Working Group is to define one or two assays that provide the strongest surrogate of broad and highly functional antiviral activity. Phase II, which included testing fractionated IgG and a limited set of corresponding sera from individuals with untreated and treated chronic infection, Vax004 vaccinees and placebo recipients, elite controllers, HIV-1 seronegatives, HIVIG, IVIG as well as b12 mutants (170 blinded test reagents) in each investigator's assay platform is complete. VISC's first round of analyses on data from seven functional assays (10 total assay readouts) is complete and was presented as a poster at AIDS Vaccine 2013. VISC and the Ackerman computational team are working on the analysis of potential correlations between these functional assays and the two multi-parameter binding assays included in this study.
· The Neutralizing Antibody Core 3 (NVITAL, VRC) has completed two phases of a new mAb combination study which aims to look for synergy or additive effects among mAb combinations. In the first phase, 15 combinations (single, double, triple and quadruple) of 4 mAbs (PG9, PGT128, VRC07, 10E8) were tested against a multi-clade panel of 125 pseudoviruses. The hypothesis was that combinations of mAbs would increase the potency and breadth over the use of each mAb independently. VISC performed a preliminary analysis of the results. For the 3 out of 4 triple mAb combinations and for all the quadruple mAb combinations, the results indicated that 99% (124 of 125) viruses exhibited an IC50 < 1µg/ml. Preliminary results suggested that utilization of mAb combinations is an alternative approach to increasing the breadth of neutralization response. To further investigate these findings, the Core expanded this study to investigate other mAb combinations (PG9, 10E8, 3BNC117, 10-1074), including two mAbs from M. Nussenzweig, against the same virus panel. Testing is complete and analysis is underway. A major goal of the analysis is to measure the magnitude of any observed incremental differences which will be used to identify the minimum mAb combination for maximum activity and determine whether the benefit of combining multiple mAbs outweighs the associated cost.