CROI 2025 Abstract eBook

Abstract eBook

Poster Abstracts

453

HIV-Induced Sialoglycans on Infected Cells Promote Immune Evasion From Myeloid Cell-Mediated Killing Shalini Singh 1 , Rui Liu 2 , Opeyemi S. Adeniji 3 , S. M. Shamsul Islam 1 , Han Xiao 2 , Mohamed Abdel-Mohsen 1 1 Northwestern University, Chicago, IL, USA, 2 Rice University, Houston, TX, USA, 3 The Wistar Institute, Philadelphia, PA, USA Background: Many viruses evade innate immune surveillance by expressing high levels of sialoglycans (sialic acid-enriched glycans) that bind to Siglecs— glyco-immune checkpoint molecules on immune cells, primarily those of myeloid origin, such as monocytes and neutrophils. This interaction suppresses the cytotoxic activity of these immune cells. HIV infection increases sialoglycan expression on the surface of CD4 + T cells; however, whether this increase facilitates the binding of HIV-infected cells to specific Siglecs on myeloid cells, thereby aiding in evasion from myeloid cell surveillance, remains unclear. Methods: Primary CD4 + T cells were infected with HIV strains (HIV TYBE or HIV DH12 ), with or without T cell activation. The expression of various Siglec ligands was analyzed using recombinant Siglec-3, -7, -9, and -10 chimeras. HIV-mediated alterations in glycosylation-associated gene expression were assessed via RNA-sequencing. The HIV-specific antibody 10-1074, conjugated with sialidase (Sia), was employed to disrupt the sialic acid-Siglec interaction specifically on HIV-infected cells. Monocyte- and neutrophil-mediated cytotoxicity against HIV-infected cell lines and autologous primary CD4 + T cells was measured using luciferase assays and p24 staining in the presence of either 10-1074 or 10-1074-Sia. Results: HIV-infected CD4 + T cells exhibited increased expression of Siglec-3, -7, and -9 ligands, but not Siglec-10 ligands, regardless of activation status. This increase was abolished by the glycosylation inhibitor BADG (Fig. 1A; p<0.0001). Transcriptomic analysis showed that HIV infection induced the expression of several glycan-related genes involved in sialoglycan production, including GALNT6 (FDR<0.01), NANP (sialic acid biosynthesis; p<0.05), and ST8SIA4 (sialyltransferase; p<0.05). In vitro , removal of sialic acid from HIV-infected cell lines using 10-1074-Sia significantly increased the cytotoxic activity of monocytes and neutrophils by 6-fold and 19-fold, respectively (p<0.02). Ex vivo , 10-1074-Sia significantly enhanced monocyte cytotoxicity against autologous primary HIV-infected CD4 + T cells compared to 10-1074 (q=0.004) (Fig. 1B). Conclusions: We have identified a novel, targetable glyco-immune mechanism through which HIV-infected cells may evade myeloid cell-mediated cytotoxicity by upregulating the expression of specific Siglec ligands. Targeting this interaction presents a promising opportunity for developing innovative immunotherapeutic strategies to eliminate HIV-infected cells. Sialidase Conjugation Enhances the Anti-HIV Activity of the 10-1074 Antibody in Humanized Mice S. M. Shamsul Islam 1 , Leila B. Giron 1 , Rui Liu 2 , Ali Danesh 3 , Shalini Singh 1 , Paul W. Denton 4 , Han Xiao 2 , Mohamed Abdel-Mohsen 1 1 Northwestern University, Chicago, IL, USA, 2 Rice University, Houston, TX, USA, 3 Weill Cornell Medicine, New York, NY, USA, 4 University of Nebraska, Omaha, NE, USA Background: HIV infection causes overexpression of sialic acid on the surface of infected cells, which binds to Siglecs—immune inhibitory receptors on innate immune cells such as natural killer (NK) cells and monocytes. This interaction triggers inhibitory signals in these immune cells that contribute to the ability of HIV-infected cells to evade immune surveillance. To counter this, we developed a targeted immunotherapy by conjugating sialidase, an enzyme that removes sialic acid, to the HIV antibody 10-1074 (referred to as 10-1074-Sia). This approach directs sialidase to HIV+ cells expressing Env antigen, stripping sialic acid from the infected cell surface and enhancing their immune elimination. We tested this strategy in vivo using a humanized mouse model of HIV infection. Methods: Five weeks old immunodeficient NSG mice (n=15) were humanized by engrafting memory CD4+ T cells from healthy donors. Mice were infected with HIV-1 SUMA , and a week later, were treated weekly for 5 weeks with either: 1) PBS (control), 2) 10-1074 combined with autologous NK cells and monocytes, or 3) 10-1074-Sia combined with autologous NK cells and monocytes. Plasma viral load and CD4+ T cell counts were monitored longitudinally by qPCR and flow cytometry, respectively. Human cytokine levels (e.g., TNFα, IFNγ, IP10) were measured longitudinally using multiplex arrays. Results: Mice treated with 10-1074-Sia did not experience significant weight loss compared to PBS-treated mice (q=0.87). While 10-1074 treatment alone The figure, table, or graphic for this abstract has been removed.

was additionally higher in treated animals (p<0.0191) (Figure 1). Although the cumulative ratios of non-synonymous to synonymous substitutions (dN/dS) across the env sequence did not differ significantly between groups (p=0.4933), four codon sites (HXB2 positions 224, 260, 529, 593) were found to be under positive selection and 8 sites (30, 33, 71, 475, 539, 575, 813, 850) under purifying selection were identified in the treated group (none of these sites were under selection in control animals. Exclusively in the treated group, Shannon entropy was elevated at specific sites in V1, V3 and fusion peptide regions, and a loss of N-glycosylation at position 130 was observed. Conclusions: Combined administration of N-803 and the 10-1074 and 3BNC117 bNAbs modulated SHIV population genetics, resulting in increased viral genetic diversity, divergence, and selection at specific sites within Env. Observed mutational patterns and glycosylation site disruption likely reflect evolutionary responses to pressure from neutralizing antibodies. Phenotypic characterization of the induced SHIV Env mutants will inform the development of HIV cure approaches.

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