CROI 2024 Abstract eBook

Abstract eBook

Poster Abstracts

paired with bnAb DH1030.1VH had no binding, in contrast to DH1030IA59VL + DH1030.1VH, suggestive of VL gene mutations in bnAb maturation. Conclusion: The DH1030 maturation pathway occurs via a series of VH and VL mutations, including HCDR2- G56R and HCDR3-S114P. An Efficient Envelope Genotypic Assay to Identify bNAb Susceptibility in Infants with HIV Kayla E Delaney 1 , Mary F. Kearney 2 , Phillip A. Bester 3 , Nicola Coetzee 1 , Susan Engelbrecht 1 , Carlo Giaquinto 4 , Paolo Rossi 5 , Shaun L. Barnabas 1 , Moira J. Spyer 6 , Mathias Lichterfeld 7 , Alfredo Tagarro 8 , Carl Lombard 1 , Mark F. Cotton 1 , Gert U. van Zyl 1 , for the EPIICAL Consortium 1 Stellenbosch University, Cape Town, South Africa, 2 National Cancer Institute, Frederick, MD, USA, 3 University of Free State, Bloemfontein, South Africa, 4 University of Padova, Padova, Italy, 5 Bambino Gesu Children's Hospital, Rome, Italy, 6 University College London, London, United Kingdom, 7 Ragon Institute of MGH, MIT, and Harvard, Cambridge, MA, USA, 8 Hospital Universitario 12 de Octubre, Madrid, Spain Background: HIV-1 envelope (Env)-specific broadly neutralizing antibodies (bNAbs) have several potential clinical benefits including in infants: Infants have limited tolerable antiretroviral treatment (ART) options, given daily for prevention and twice daily for treatment. In contrast, bNAbs with modified Leucine-Serine (LS) Fc receptors permit infrequent subcutaneous dosing. Moreover, unlike ART, bNAbs may facilitate viral reservoir reduction and contribute to functional cure. However, data on HIV-1 Env evolution and bNAb susceptibility in perinatally infected infants are limited. Methods: The evolution of Clade C Env in five infants (4 female) born with HIV-1 and with intermittent viraemia despite early ART was investigated over 19.3 (range: 16.9 - 21) months. A single-genome sequencing approach using Oxford Nanopore Technologies (ONT) was developed and validated using Sanger Sequencing as reference. In short, consensus sequences were constructed for each single genome using NECAT, a published bioinformatics pipeline that corrects ONT error. Defective individual genomes containing stop codons were excluded. The susceptibility of the remaining genomes to 33 bNAbs were investigated using the bNAb- Resistance Predictor (bNAb-ReP) machine learning algorithm. Results: The intra-patient average pairwise distances (APD) ranged from 0.08% - 1.29% (median: 0.43%). Different evolutionary patterns were observed. Env length variation emerged in 4 out of 5 infants. Phylogenetic trees showed temporal structure in four cases with new variants emerging either from majority or minority populations or apparent ancestral or archived variants. All variants were identified as CCR5-tropic by three genotypic prediction models. Predicted bNAb susceptibility showed much higher inter-patient than intra patient variability with PGDM1400, PGT128 and 3BNC117 (Table 1) predicted to have the highest susceptibilities overall. Conclusion: As phenotypic bNAb susceptibility testing is costly and has low reproducibility, we developed an efficient Env genotypic assay, combining single-genome sequencing with ONT to accommodate Env sequence length variation. Applying our workflow, the predicted susceptibility to bNAbs varied across individuals due to high levels of inter-patient Env diversity. Early ART treated infants often have viraemia due to adherence challenges. However, early intra-patient Env evolution was limited and unlikely to impact bNAb susceptibility. Updated prediction algorithms require validation across HIV-1 subtypes.

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MHRP01, an MPER Targeting bNAb, Enables Further Definition of the 4E10-Class of bNAbs Juhi Arora 1 , Paul Thomas 1 , Gina Donofrio 1 , Rajeshwer S. Sankhala 1 , Nicole Doria-Rose 2 , Chaim A. Schramm 2 , Vincent Dussupt 1 , Lauren Smith 1 , Letzibeth Mendez-Rivera 1 , Lindsay Wieczorek 1 , Sandhya Vasan 3 , Julie Ake 1 , Merlin L. Robb 3 , M. Gordon Joyce 1 , Shelly J. Krebs 1 1 Walter Reed Army Institute of Research, Silver Spring, MD, USA, 2 National Institute of Allergy and Infectious Diseases, Baltimore, MD, USA, 3 Henry M Jackson Foundation, Bethesda, MD, USA Background: The membrane proximal external region (MPER) is a conserved site of vulnerability on the HIV- 1 gp41 envelope, targeted by highly potent broadly neutralizing monoclonal antibodies (bNAbs) such as 4E10, VRC42 and PGZL1. Although elicited by unrelated persons living with HIV (PLWH), from multiple different HIV-1 subtypes, these bNAbs have similar features. We report the isolation of 4E10-class bNAb, MHRP.01, from an untreated person living with subtype B HIV infection that had 100% neutralization breadth against a 34- pseudovirus (pSV) panel and predicted specificity for MPER binding mAbs. Using bNAbs 4E10, VRC42, and MHRP.01, we provide evidence of an amino acid signature pertaining to 4E10-class bNAbs. Methods: CD19+/IgD-/IgM- B cells were sorted from donor PBMCs by flow cytometry and cultured in 384- well plates. Cultured supernatants were screened via microneutralization assays against HIV-1 pSVs. B cell receptors from wells with neutralization >70% were sequenced, followed by cloning and expression of heavy and light chain genes to produce monoclonal antibodies (mAbs). mAbs were characterized for binding, epitope mapping and neutralization assays against panels of diverse HIV-1 strains. Based on crystal diffraction analysis, mutations were introduced in the heavy chain of the MHRP.01 to generate a 4E10-like bNAb signature, and the resulting mutant mAbs were further characterized. Results: MHRP.01 neutralized 99.5% of a globally diverse 208-pSV panel with IC 50 of 1.49 μg/ml and demonstrated striking similarities to 4E10, VRC42, and PGZL1, including utilization of VH1-69 and VK3-20 gene usage and similar critical residue epitopes. Crystallization of MHRP.01 revealed residues important for MPER binding, which bound in the same conformation as 4E10 and VRC42. Mutation of glycine at 50 or proline at 108 locations within CDRH2 and CDRH3 respectively abolished binding to the MPER peptide and neutralization of autologous pSV (Fig 1), with further paratope residues contributing to a definable sequence signature. Conclusion: MPER targeting bNAb, MHRP.01 contained identical germline usage, binding angle of approach and neutralization breadth as 4E10-class bNAbs. Structural analysis reveals a 4E10-like bNAb signature important for MPER binding and neutralization. MPER represents a common epitope which has the potential to elicit similar B cell responses from several PLWH, making it desirable for vaccine design.

Poster Abstracts

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CROI 2024