CROI 2020 Abstract eBook

Abstract eBook

Poster Abstracts

292 TARGETING HIV ENV TO CD40 LEADS TO HIV-SPECIFIC POLYCLONAL B CELLS IN HUMANIZED MICE Veronique Godot 1 , Colas Tcherakian 2 , Laurine Gil 3 , Iñaki Cervera-Marzal 3 , Hugo Mouquet 4 , Guangming Li 5 , Liang Cheng 5 , Jean Daniel Lelievre 2 , Giuseppe Pantaleo 6 , Mireille Centlivre 2 , Sandy Zurawski 7 , Gerard Zurawski 7 , Pierre Milpied 3 , Lishan Su 5 , Yves Levy 2 1 INSERM, Paris, France, 2 Vaccine Research Institute, Créteil, France, 3 INSERM, Marseille, France, 4 Institut Pasteur, Paris, France, 5 University of North Carolina at Chapel Hill, Chapel Hill, NC, USA, 6 University of Lausanne, Lausanne, Switzerland, 7 Baylor Institute for Immunology Research, Dallas, TX, USA Background: Challenges in the development of HIV-1 vaccines are to more accurately direct protective immune responses and develop appropriate animal models. Methods: Mice with a functional human immune system (HIS) were immunized with either anti-CD40 mAb in which the Fcgamma domains are fused to the HIV-1 envelop protein (gp140ZM96) (anti-CD40.Env gp140) with CpG-B (w0, w3, w5) (CD/CD group) or Nyvac-KC pox vaccine encoding gp140ZM96 with CpG-B (w0) followed by two injections of anti-CD40.Env gp140 with CpG-B (w3, w5) (N/CD group). B- and T-cell responses were studied at w6 in blood and spleens and compared to control animals (PBS or CpG-B only, C group). BCR diversity was analysed by single cell RNA sequencing (scRNAseq). Results: As compared to C group, anti-CD40.Env gp140 vaccine induced a sustained CD40 expression on myeloid DCs and B cells. In both vaccine groups, gp140ZM96-specific CD4+memory T cells and IgG-switched B cells were elicited at w6. Among these cells, gp140ZM96-specific IgG+ B cells were induced in the spleen and blood with a higher frequency in the N/CD group (7,360 cells/mL [4,022-13,640] and 1,421 cells/mL [1,023-2,830] in the spleen and 356 cells/mL [38-193] and 99 cells/mL [198-951] in the blood; P<0.05 for both comparisons). Increased frequency of blood ICOS+CXCR5+ Tfh-like cells significantly correlated with the induction of gp140ZM96-specific IgG+ B cells in vaccine groups (R=0.70, p=0.004). Analysis of Ig VH and Vk gene diversity showed a large diversity of IgV gene usage in non-specific memory B cells while an enrichment of VH3 and J(k) 4/5 family gene usage was observed in the gp140ZM96-specific IgG+ B cells. In the N/CD group, these cells exhibited a BCR with longer CDRH3 lengths (37% of clones with CDRH3 > 18 aa and up to 28 aa) and a higher rate of somatic hypermutations. Clonal evolution assessed by phylogenic trees was observed in both vaccine groups with a higher diversity in the N/CD group. Conclusion: Our results showed that HIS-mice vaccinated with the anti-CD40. Env gp140 vaccine given as a prime or a boost of Nyvac-KC vector elicited T and B cell-specific responses with a diverse antibody B cell repertoire. Interestingly, gp140ZM96-specific IgG-switched memory B cells exhibit antigen-driven antibody maturation characteristics. 293 CD40-TARGETED VACCINE INCREASES MAGNITUDE OF HIV-ENV SPECIFIC RESPONSES Romain Marlin 1 , Sabine Tricot 1 , Francis Relouzat 1 , Christiane Moog 2 , Laëtitia Bossevot 1 , Sandy Zurawski 3 , Gerard Zurawski 3 , Andrès Salazar 4 , Catherine Chapon 1 , Nathalie Dereuddre-Bosquet 5 , Mireille Centlivre 6 , Yves Levy 6 , Roger Le Grand 5 1 Infectious Diseases Models for Innovative Therapies, Fontenay-aux-Roses, France, 2 INSERM, Strasbourg, France, 3 Baylor Institute for Immunology Research, Dallas, TX, USA, 4 Oncovir Inc, Washington DC, Maryland, USA, 5 INSERM, Fontenay-aux-Roses, France, 6 Vaccine Research Institute, Créteil, France Background: The development of DC-targeted vaccines aims to increase immunogenicity of proteins through improved delivery of the antigens to specific antigen-presenting cells playing a key role in inducing and regulating immune memory. CD40 signaling is essential for T cell-dependent humoral responses and targeting vaccine antigen to CD40 expressing APC seems therefore an attractive option to promote anti-HIV antibody development. Methods: To determine the impact of DC targeting on immune responses, we analyzed cellular changes at immunization site. Twelve cynomolgus macaques were immunized with homologous prime-boost strategy by HIVgp140 protein fused with anti-CD40 targeting module or with IgG4 irrelevant control. Cellular trafficking was analyzed in injection site and draining lymph node by in vivo imaging after boost. Impact on immune responses was also evaluated over time. Results: Combination of in vivo imaging techniques (near infrared imaging, probe-based confocal laser endomicroscopy and two-photon microscopy)

natural occurring bnAbs. Comparison of wild type and CD4bs-knockout Envs allowed exploring the impact of CD4bs bnAb activity. Of note, IgG1 reactivity of trimeric CD4bs immunogens were good predictors of neutralization breadth, while the monomeric CD4bs tailored immunogens EOD-GT8 and RSC3 did not differentiate bnAb activity. Conclusion: Focusing on closely matched bnAb and nnAb inducers, the XbnAb cohort captures the essence of the Swiss 4.5K Screen, providing means to derive population relevant information without the need to screen thousands of individuals. Highlighting the unique capacity of the XbnAb cohort we demonstrate a differential capacity of candidate antigens in engaging natural occurring Abs that needs to be considered when selecting immunogens for further development. 291 ACUTE INFECTION B-CELL DETERMINANTS PREDICT DEVELOPMENT OF NEUTRALIZATION BREADTH Samantha Townsley 1 , Gina Donofrio 1 , Ningbo Jian 1 , David Leggat 2 , Vincent Dussupt 1 , Letzibeth Mendez-Rivera 1 , Nicole Doria-Rose 2 , John R. Mascola 2 , Morgane Rolland 1 , Sodsai Tovanabutra 1 , Adrian B. McDermott 1 , Nelson L. Michael 1 , Merlin L. Robb 1 , Shelly J. Krebs 1 , for the RV217 Study Group 1 Walter Reed Army Institute of Research, Silver Spring, MD, USA, 2 NIAID, Bethesda, MD, USA Background: Determining which immunological mechanisms contribute to the development of broadly neutralizing antibodies (bNAbs) during HIV-1 infection is a goal to inform vaccine design. It is not understood if factors during the acute stages of infection impact the generation of neutralization breadth years later. Methods: Utilizing 178 longitudinal samples from 72 HIV-1 infected, ART-naïve individuals within the RV217 cohort, we identified 16 individuals who neutralized >70% of a panel of 34 viruses (broad neutralizers) and 12 individuals not able to neutralize >35% after 3 years of infection (non-broad neutralizers). Founder env genes were sequenced, and gp140 founder Env proteins were produced to characterize respective early autologous B cell responses. Founder Env+ and total B cell populations were phenotyped at pre- infection, peak viral load (day 11-18), month 1 (day 30-43), and chronic infection timepoints (day 391-2115). Results: Reduced peripheral B cells starting at month 1 post-viremia were predictive of the development of bNAbs (HR=0.37, 95% CI: 0.18-0.76, p=0.007). Individuals with less than 160 B cells/mm 3 at month 1 were 42 times more likely to develop neutralization breadth. Reduced peripheral B cells were driven by a reduction in peripheral naïve B cells occurring at 14 days post-viremia. Naïve B cell frequencies at day 14 inversely correlated with frequencies of founder Env- specific (p<0.02), plasmablast (p<0.0001), and integrin beta7+ (p<0.001) B cell populations, suggesting early B cell engagement, differentiation, and migration to lymph nodes. Additionally, increased B cell engagement of respective founder gp140 Envelopes at 1 month predicted the development of bNAbs (OR=1.13, 95% CI: 1.02-1.28, p=0.035). Individuals with high engagement of their respective autologous founder Env at 1 month had a higher probability of developing neutralization breadth compared to individuals with low engagement of their autologous founder Env (p=0.02). Conclusion: These data demonstrate development of neutralization breadth is influenced by early immunological mechanisms within the first month of acute infection. The reduction of peripheral naïve B cells in broad neutralizers and early, heightened engagement of the founder Env favored the development of broadly neutralizing antibodies, providing evidence that acute infection events lead to downstream functional outcomes.

Poster Abstracts

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