CROI 2024 Abstract eBook

Abstract eBook

Oral Abstracts

103

CD4 Binding Site Glycan-Deficient SHIVs Elicit Broadly Neutralizing Antibodies in Rhesus Macaques Daniel J Morris 1 , Hui Li 1 , Jinery Lora 1 , Kirsten Sowers 1 , Christian Martella 1 , Yingying Li 1 , Barton F. Haynes 2 , Tongqing Zhou 3 , Peter D. Kwong 3 , George M. Shaw 1 1 University of Pennsylvania, Philadelphia, PA, USA, 2 Duke Human Vaccine Institute, Durham, NC, USA, 3 National Institutes of Health, Bethesda, MD, USA Background: Previous work has demonstrated that modifying soluble HIV-1 envelope (Env) trimers to remove glycans around the CD4 binding site (CD4bs) can immunofocus potent neutralizing antibody (NAb) responses to this epitope. However, such immunogens generally did not elicit broadly neutralizing antibodies (bNAbs). Understanding how to better boost these responses can inform vaccine design. Infection of rhesus macaques with replicating simian human immunodeficiency viruses (SHIVs) bearing WT glycan-intact Envs rarely elicits bNAbs targeting the CD4bs. Here, we designed novel SHIVs lacking glycans surrounding the CD4bs (197, 363, and 462) to test the hypothesis that infection with these evolving SHIVs could immunofocus, boost, and affinity- mature CD4bs-targeted NAb and bNAb responses. Methods: We disrupted glycosylation sequons at the above residues in three SHIVs bearing primary transmitted/founder Envs (CH505, BG505 and CH1012) and used these to intravenously infect a pilot cohort of 14 rhesus macaques (RMs). RMs were monitored to evaluate viral kinetics, Env sequence evolution, and NAb and bNAb development. Results: 9 of 14 RMs exhibited ideal viral kinetics for further analysis. All 9 RMs developed potent autologous neutralizing responses targeting the protein surface beneath the engineered glycan hole. 4 of 9 RMs developed responses capable of neutralizing heterologous glycan-deficient viral strains. Longitudinal sequencing of plasma viral RNA revealed rapid, sequential restoration of the deleted glycans as well as CD4bs bNAb escape mutations arose temporally with rising neutralizing titers. Two RMs developed antibody responses capable of neutralizing WT heterologous viruses. Based on these results, we downselected from these constructs SHIV.CH505.CD4bs.GH to infect an additional 8 RMs. We observed CD4bs-targeted neutralization breadth in an additional 6 RMs. Epitope mapping of these broad responses showed that 7 of 8 RMs targeted the CD4bs. Conclusion: These results show that SHIV Env trimers with targeted glycan deletions can immunofocus B cell responses to the CD4bs. Viral evolution in response to these glycan hole targeted NAbs can boost and affinity mature these responses, in some cases leading to bNAbs that target WT heterologous viruses with intact glycan shields. Ongoing studies will isolate and characterize mAbs responsible for this breadth and analyze Env-Ab coevolution to identify key Envs that can be selected as priming and boosting immunogens. MHC-E Presentation Mediates SIV-Specific NK Cell Responses in SIV-Infected Rhesus Macaques Philippe Rascle , Rhianna Jones, Griffin Woolley, Kyle Kroll, Karen Terry, Esther Lee, Stephanie Jost, Keith Reeves Duke Human Vaccine Institute, Durham, NC, USA Background: Natural killer (NK) cells provide rapid and robust responses against viral infections. Multiple studies have shown that NK cells are also capable of antigen-specific recall to eliminate infected cells. In nonhuman primates (NHP), antigen-specific memory-like NK cell can be designed by MHC-E dependent response. During SIV infection, the stabilized MHC-E molecule may induce a potent pathway to restrict the virus via antigen-specific memory NK responses. Methods: To study antigen-specific NK cells in NHP, we developed a novel in vitro method to clonally expand single rhesus macaque (RM) NK cells (rhNKCL) from SIV naive or chronically infected RM. We identified SIV- derived peptides by in silico analysis and confirmed their MHC-E binding using a peptide stabilization assay on K562 cells stably expressing MHC-E (HLA-E and Mamu-E) and primary RM cells. We characterized the effector functions of NK and rhNKCL cells via intracellular staining and cytotoxicity assays in combination with K562 cell lines or autologous BLCL loaded with SIV-derived peptides. Results: Ten SIV-derived peptides showed MHC-E stabilization on K562 MHC-E+ (HLA-E and Mamu-E) cells and RM primary cells. Enriched NK cells exhibited an increase in IFNgamma, TNFalpha, and Ki67 during SIV acute infection against SIV-derived peptides, and a decrease in these responses in chronic infection. Interestingly, NK cells from RM with chronic SIV infection showed higher cytotoxic responses compared to NK cells from SIV-naïve RM against K562 Mamu-E+ cells loaded with SIV-derived peptides. To further investigate

Oral Abstracts

102

Multi-Specificity Is a Common Trait of HIV-1 Broad Neutralizing Capacity Peter Rusert 1 , Chloé Pasin 2 , Merle Schanz 1 , Borys Pedenko 3 , Daniel Schmidt 1 , Irene A. Abela 2 , Nikolas Friedrich 1 , Cyrille Niklaus 1 , Michèle Sickmann 1 , Jaqueline Weber 1 , Gregory Effantin 3 , Winfried Weissenhorn 3 , Huldrych F. Günthard 2 , Roger Kouyos 2 , Alexandra Trkola 1 1 University of Zurich, Zurich, Switzerland, 2 University Hospital Zurich, Zurich, Switzerland, 3 Université Grenoble Alpes, Grenoble, France Background: Multi-specific responses have been described in rare people who evolved broadly neutralizing antibody (bnAb) activity in HIV-1 infection but their relevance remains unclear. Here we screened the Swiss HIV Cohort Study for multi-specificity by examining the XbnAb cohort comprising bnAb inducers (N=304) identified in the Swiss 4.5k Screen (Rusert Nat Med 2016). Methods: Plasma neutralization fingerprints of bnAb inducers were evaluated against a 41-virus multiclade panel and compared to reference fingerprints of known bnAbs using an established Spearman based correlation method and a novel delineation strategy, termed virus panel classification, we developed to record multi-specificity. BCR were cloned from 16 cases by 10xGenomics and bnAbs of interest epitope mapped (mutational scanning, competition binding, mutant neutralization, cryo-EM). Results: Classical bnAb plasma delineation of the XbnAb cohort assigned a single bnAb activity in 90% of plasmas. As the prediction records a dominant activity, secondary multi-specific activity cannot be excluded also in successfully assigned plasmas. This hidden extent of multi-specificity can be substantial as shown by elite neutralizer S51434, a Subtype B infected, slow progressor with predicted silent face activity based on the Spearman correlation method, from which we identified five distinct bnAb types as CD4bs, MPER, a fusion peptide/interface, PGT145-like and a novel V3-glycan bnAb type, with moderate to high breadth (44 - 80%). Virus panel prediction, we developed a novel delineation strategy for multi-specific responses, correctly classified S51434 as multi-specific. Across the XbnAb cohort the virus panel strategy identified a high proportion of bnAb inducers with one dominant bnAb activity (203/304) alongside a substantial number of individuals with multi-specificity (101/304), comprising mostly 2 to 3 predicted bnAb specificities. Extending the comparison of cloned bnAbs and specificity calling by the virus panel method to in total 16 bnAb inducers, substantiates the wide occurrence of multi-specificity. Conclusion: Employing a new bnAb specificity prediction tool, the virus-panel fingerprinting method, we demonstrate that multi-specific bnAb activities are common in HIV-1 infection and can lead to elite neutralization. Our findings call for a paradigm shift in the evaluation of bnAb responses, where multi- specificity must be considered as likely as single-specificity and should become the ultimate goal of vaccine-induced responses.

104

17

CROI 2024