CROI 2015 Program and Abstracts

Abstract Listing

Poster Abstracts

345 V1V2 Neutralizing Epitopes Are ConservedWithin Divergent Groups of HIV-1 Marion Morgand 1 ; Mélanie Bouvin-Pley 1 ; Craig S Pace 2 ; David Ho 2 ; Pascal Poignard 3 ; Marie Pancera 4 ; Jean-Christophe Plantier 5 ; Francois Simon 6 ; Martine Braibant 1 ; Francis Barin 7 1 Université de Tours, Inserm U966, Tours, France; 2 Aaron Diamond AIDS Research Center, The Rockefeller University, New York, NY, US; 3 Department of Immunology and Microbial Science, The Scripps Research Institute, La Jolla, CA, US; 4 Vaccine Research Center, NIAID, NIH, Bethesda, WA, US; 5 Université de Rouen, CHU Charles Nicolle, Rouen, France; 6 Laboratoire de Virologie, Hôpital St Louis, Paris, France; 7 Université de Tours, Inserm U966, Laboratoire de Bactériologie-Virologie, CNR du VIH, CHU Bretonneau, Tours, France Background: HIV-1 has been classified into 4 groups: M, N, O and P. These last years, highly potent broadly neutralizing monoclonal antibodies (bNabs) have been obtained from individuals infected by HIV-1 group M variants. The aim of this study was to analyze the cross-group neutralization potency of these bNabs using a large panel of non-M primary isolates (PI). Methods: The sensitivity to neutralization of 16 non-M HIV-1 PIs (12 O, 2 N, 1 P, 1 M/O recombinant) was analyzed in a neutralization assay using TZM-bl cells. Twenty two HuMoNabs were used. VRC01, VRC03, 3BNC117 and five clonal variants of NIH45-46 G54W target the CD4 binding site (CD4bs). PG9, PG16, PGT145 and PG9-PG16-RH target the N160 glycan-V1V2 site. PGT121, PGT128 and 10-1074 target the N332 glycan-V3 site. 2F5, 4E10 and 10E8 target the MPER of gp41. 8ANC195 target a complex epitope spanning both Env subunits. Two bispecific antibodies that combine the inhibitory activity of an anti-CD4 with that of PG9 or PG16 (BibNabs) were included in the study (PG9-iMab and PG16-iMab). Results: Cross-group neutralization was observed only with the bNabs targeting the N160 glycan-V1V2 site. Four group O PIs, one group N PI and the group P were neutralized by PG9 and or PG16 at low concentrations (0.04-0.9.39 m g/mL). None of the non-M PIs was neutralized by the bNabs targeting other regions at the highest concentration tested (10 m g/mL), except 10E8 that neutralized weakly two group O PIs (3.35-3.69 m g/mL). The BibNabs neutralized very efficiently all the non-M PIs with IC50 below 1 m g/mL, except two group O strains. The high potency of the BibNabs was mediated by the gp120-binding activity of PG9 and PG16 scFVs. Conclusions: The N160 glycan-V1V2 site is the most conserved neutralizing site within the four groups of HIV-1. It makes it a potentially interesting target for development of HIV vaccine immunogens. The corresponding bNabs could be useful for immunotherapeutic strategies in patients infected by non-M variants. 346 Improving Neutralization Potency and Breadth by Combining Broadly Reactive HIV-1 Antibodies Targeting Major Neutralization Epitopes Rui Kong 1 ; Mark Louder 1 ; KshitijWagh 2 ; Robert Bailer 1 ; Kelli Greene 3 ; Hongmei Gao 3 ; Michel Nussenzweig 4 ; Bette Korber 2 ; David Montefiori 3 ; John Mascola 1 1 Vaccine Research Center, NIAID, NIH, Bethesda, MD, US; 2 Los Alamos National Laboratory, Los Alamos, NM, US; 3 Duke University Medical Center, Durham, NC, US; 4 The Rockefeller University, New York, NY, US Background: The isolation of broadly neutralizing HIV-1 monoclonal antibodies (mAb) to distinct epitopes on the viral envelope glycoprotein (Env) provides the potential to use combinations of mAbs for prevention and treatment of HIV-1 infection. The potency and breadth of mAb combinations have not been well characterized. Methods: Two sets of combiantions were tested for neutralization breadth and potency on 125 viruses in TZM-bl assay. Set I includes VRC07 (CD4bs), PG9 (V1V2-glycan), PGT128 (V3-glycan) and 10E8 (MPER). Set II substituted VRC07 and PGT128 with 3BNC117 and 10-1074. In each set, 6 double, 4 triple and 1 quadruple mAb mixtures were made by combining mAbs at equal concentration. To study the interaction of mAbs, the experimental IC50 titers were compared to the titers predicted based on additive model. Results: All combinations showed substantially improved neutralization breadth and potency compared to the corresponding single mAbs. At an IC 50 cutoff of 1 μ g/ml, VRC07 neutralized 83% of viruses, representing the best coverage by a single mAb, while double combinations neutralized 89-98%, and all triple and quadruple combinations neutralized 98-100%. IC50 and IC80 heat maps showed that a positive antibody in the mix enabled neutralization of strains that were resistant to the negative antibody in the mix, suggesting that the complementary neutralization profiles of the individual mAbs contributed to the improved breadth. When the experimental IC50 titers were compared to IC50 predicted based on additive model, an overall less than two fold differences were observed for all combiantions, suggesting no substantial synergy or antagonism. In 15 out of 22 combinations, including all double and triple combinations with CD4bs, V1V2-glycan and MPER mAbs, small but statistically significat increases were observed in experimetnal titers when compared to the additive prediction. Conclusions: All 22 double, triple and quadruple combiantions containing mAbs targeting CD4bs, V1V2 glycan, V3 glycan and MPER epitpes showed substaintially improved neutralization breadth and potency. Overall the improvement was closely predicted by additive effect model and explained by complementary neutralization profiles of single Background: HIV-1 infected individuals, classified as long-term non-progressors (LTNP), remain healthy for many years in absence of antiretroviral therapy, with stable CD4+ T lymphocyte counts and low levels of viral replication. Neutralization studies in sera from LTNPs with undetectable viremia, showed little neutralizing activity (Nab) because of a reduced antigenic stimulation of B cells. A broad NAb response has been associated with prolonged high-levels of antigenic stimulation, in terms of high viral load and viral diversity. In fact, patients infected with two different HIV-1 viruses showed enhanced heterologous NAb response. However, little is known about the neutralizing response in LTNP patients with dual infection (DI) . Methods: Four DI versus 6 single-infected LTNP patients were compared in their Nab response. Both groups were matched according to years after HIV-1 diagnosis, viral loads and T CD4+ cell counts. NAb response in samples from DI versus single-infected patients, were tested in two samples. A fixed 1/200 serum dilution was tested against a previously described mini-panel of six recombinant viruses from 5 different subtypes and tropisms; Nab breadth, expressed as number of subtypes crossed, was analyzed. To investigate if broader Nab response was related to the viral diversity generated by the DI, diversity in the viral quasispecies was measured by calculating the Shannon Entropy. Results: LTNP DI patients showed a Nab response (median of 3.0 ± 0.8) significantly (p= 0.0018) broader than single-infected patients (median of 1.1 ± 1.1). Association between the number of subtypes crossed and viral diversity (Shannon entropy) showed a high positive correlation (p= 0.0022, r 2 = 0.071). The median Shannon entropy value of the viral population was statistically (p= 0.0011) higher in DI (0.0775) than in single-infected (0.0150) patients, suggesting that the higher viral diversity due to DI was associated with a broader NAb response. Conclusions: This study analyzed for the first time the neutralization breadth in LTNP patients dually-infected by HIV-1. The higher diversity within the quasispecies generated by HIV-1 DI has contributed to the improvement of neutralization breadth in LTNP patients. These results could be very useful for HIV research and vaccine strategies. 348 Characterization of CD4 Independent HIV-1 Envelope as Potential Immunogens Lifei Yang 1 ; Bradley Cleveland 1 ; Andrea P. Jordan 2 ; Patricia Polacino 1 ; James A. Hoxie 2 ; Shiu-Lok Hu 1 1 University of Washington, Seattle, WA, US; 2 University of Pennsylvania, Philadelphia, PA, US Background: We reported earlier that removal of a highly conserved N-linked glycan N197 (N7) on the primary HIV-1 isolate 89.6 improved the immunogenicity of the envelope (Env) protein. Deletion of this glycan made the 89.6 Env more sensitive to CD4-binding site-specificantibodies (Abs) and less dependent on the CD4 receptor to initiate infection. However, it is not clear if the improvement in immunogenicity of 89.6 Env is related to the N7 glycan site mutation per se or the acquisition of a partial CD4i phenotype. mAbs. Subtle but consistent favorable interactions were observed in some mAb combinations. 347 Improved Antibody Cross-Neutralizing Activity in HIV-1 Dual-Infected LTNP Patients Maria Pernas 1 ; Concepción Casado 1 ;Victor Sanchez-Merino 2 ; Alberto Sanchez-Merino 2 ; Isabel Olivares 1 ; eloisaYuste 2 ; Cecilio Lopez-Galíndez 1 1 Instituto de Salud Carlos III, Majadahonda, Spain; 2 Institut d’Investigacions Biomediquès, Barcelona, Spain

Poster Abstracts

268

CROI 2015