Background
Broadly neutralizing antibodies (bNAbs) are under study to enable ART-free remission in perinatal HIV-1. Phenotypic testing would guide targeted bNAb therapy but is limited by low assay yields and plasma volume in children. These barriers may be overcome with a proviral sequencing approach.
Methods
bNAb sensitivity was assessed using near full-length single genome sequencing on infants with in utero HIV-1 enrolled in Version 1.0 of IMAACT P1115. Infants with ≥20 HIV-1 DNA copies/106 PBMCs and ≥5 µL of remnant genomic DNA were eligible for study (N=28) from 6 countries and 5 HIV-1 subtypes, mostly C (75%). Representative env sequences were selected by closest identity to consensus. Phenotypic testing was performed with the TZM-bl neutralization assay against a panel of 11 bNAbs targeting CD4 (1-18, 3BNC117, N6LS, VRC01, VRC07-523LS), V1V2 (CAP256J3LS, CAP256V2LS, PGDM1400), or glycan-V3 binding site (10-1074, ePGT121.L15, PGT121.414LS) and 1 targeting CD4 (Ibalizumab). Bliss-Hill modeling was used to predict neutralization bNAb combinations and determine optimal individual and universal approaches, accounting for breadth and potency.
Results
Intact genomes were detected in 28 infants from 257 sequences (median 8.5 per infant; range 1-31). Env sequences were homogenous within individuals (median 99.9% shared identity; range 99.2-100%). Pseudovirus generation and subsequent phenotypic testing was successful in 24/28 (86%). Neutralization breadth at IC50 <50 µg/mL averaged 90% for CD4-, 63% for V1V2-, and 56% for glycan-V3-binding bNAbs while breadth at IC80 ≤1 µg/mL averaged 39%, 29%, and 31% (Figure 1). Bliss-Hill modeling identified VRC07523LS+CAP256V2LS+10-1074 as the most effective universal triple bNAb combination (72% breadth at IC80 ≤1 µg/mL, geo. mean 0.16 µg/mL); similar results are achieved when PGDM1400 replaces CAP256V2LS. With an individual approach, maximal neutralization breadth is achieved with two bNAbs (76% breadth at IC80 ≤1 µg/mL). Interestingly, Ibalizumab paired with a V1V2 or glycan-V3-binding bNAb increases breadth to >84% at IC80 ≤1 µg/mL.
Conclusions
Proviral sequencing provided bNAb sensitivity profiles from 86% of infants, supporting the potential for proviral genomes to guide bNAb therapy for in utero HIV-1. These data provide IC50 and IC80 benchmarks for viruses acquired by in utero transmission and a framework for precision-guided approaches to bNAb therapy for infants with in utero HIV-1.
Table or Figure
