Characterizing the Relationship Between Neutralization Sensitivity and env Gene Diversity During ART Suppression

Autologous neutralizing antibody responses after antiretroviral therapy in acute and early HIV-1

BACKGROUNDEarly antiretroviral therapy initiation (ARTi) in HIV-1 restricts reservoir size and diversity while preserving immune function, potentially improving opportunities for immunotherapeutic cure strategies. For antibody-based cure approaches, the development of autologous neutralizing antibodies (anAbs) after acute/early ARTi is relevant but is poorly understood.METHODSWe characterized antibody responses in a cohort of 23 participants following ARTi in acute HIV (<60 days after acquisition) and early HIV (60-128 days after acquisition).RESULTSPlasma virus sequences at the time of ARTi revealed evidence of escape from anAbs after early, but not acute, ARTi. HIV-1 envelopes representing the transmitted/founder virus(es) (acute ARTi) or escape variants (early ARTi) were tested for sensitivity to longitudinal plasma IgG. After acute ARTi, no anAb responses developed over months to years of suppressive ART. In 2 of the 3 acute ARTi participants who experienced viremia after ARTi, however, anAbs arose shortly thereafter. After early ARTi, anAbs targeting those early variants developed between 12 and 42 weeks of ART and continued to increase in breadth and potency thereafter.CONCLUSIONResults indicate a threshold of virus replication (~60 days) required to induce anAbs, after which they continue to expand on suppressive ART to better target the range of reservoir variants.TRIAL REGISTRATIONClinicalTrials.gov NCT02656511.FUNDINGNIH grants U01AI169767, R01AI162646, UM1AI164570, UM1AI164560, U19AI096109, K23GM112526, T32AI118684, P30AI045008, P30AI027763, R24AI067039; Gilead Sciences grant INUS2361354; Viiv Healthcare grant A126326.

Broadly neutralizing antibodies targeting HIV: Progress and challenges

Anti-HIV broadly neutralizing antibodies (bNAbs) offer a novel approach to treating, preventing, or curing HIV. Pre-clinical models and clinical trials involving the passive transfer of bNAbs have demonstrated that they can control viremia and potentially serve as alternatives or complement antiretroviral therapy (ART). However, antibody decay, persistent latent reservoirs, and resistance impede bNAb treatment. This review discusses recent advancements and obstacles in applying bNAbs and proposes strategies to enhance their therapeutic potential. These strategies include multi-epitope targeting, antibody half-life extension, combining with current and newer antiretrovirals, and sustained antibody secretion.

To prescreen or not to prescreen for broadly neutralizing antibody sensitivity in HIV cure-related trials

The use of broadly neutralizing antibodies (bNAbs) as a cure-related research strategy for human immunodeficiency virus (HIV) has gained attention from the scientific community. bNAbs are specialized antibodies that target HIV-1 by binding to proteins on the surface of the virus, preventing the infection of human cells. In HIV-1 clinical studies assessing the use of bNAbs, it has been common practice to prescreen potential participants for bNAb sensitivity. However, the use of pre-screening in HIV-1 bNAb clinical trials is a topic of ongoing debate, with regard to its potential benefits and limitations. In this paper, we examine the possible benefits and limitations of pre-screening for bNAb sensitivity in HIV-1 cure-related studies, and suggest alternative methods which may be more effective or efficient at saving costs and time. Ultimately, the decision to use pre-screening in HIV-1 bNAb clinical trials should be based on a careful assessment of the potential benefits and limitations of this approach, as well as the specific needs, goals, design, and population of the study in question.

Persistence of envelopes in different CD4+ T-cell subsets in antiretroviral therapy-suppressed people with HIV

OBJECTIVES

Despite suppressive antiretroviral therapy (ART), HIV can persist in a diverse range of CD4+ T-cell subsets. Through longitudinal env sampling from people with HIV (PWH) on ART, we characterized the persistence and phenotypic properties of HIV envs over two time-points (T1 and T2).

METHODS

Longitudinal blood and lymphoid tissue samples were obtained from eight PWH on suppressive ART. Single genome amplification (SGA) was performed on env to understand the genetic diversity and degree of clonal expansions over time. A subset of envs were used to generate pseudovirus particles to assess sensitivity to autologous plasma IgG and broadly neutralizing antibodies (bNAbs).

RESULTS

Identical env sequences indicating clonal expansion persisted between T1 and T2 and within multiple T-cell subsets. At both time-points, CXCR4-tropic (X4) Envs were more prevalent in naive and central memory cells; the proportion of X4 Envs did not significantly change in each subset between T1 and T2. Autologous purified plasma IgG showed variable neutralization of Envs, with no significant difference in neutralization between R5 and X4 Envs. X4 Envs were more sensitive to neutralization with clinical bNAbs, with CD4-binding site bNAbs demonstrating high breadth and potency against Envs.

CONCLUSION

Our data suggest the viral reservoir in PWH on ART was predominantly maintained over time through proliferation and potentially differentiation of infected cells. We found the humoral immune response to Envs within the latent reservoir was variable between PWH. Finally, we identified coreceptor usage can influence bNAb sensitivity and may need to be considered for future bNAb immunotherapy approaches.

Subtle Longitudinal Alterations in Env Sequence Potentiate Differences in Sensitivity to Broadly Neutralizing Antibodies following Acute HIV-1 Subtype C Infection

Broadly neutralizing antibodies (bNAbs) for HIV-1 prevention or cure strategies must inhibit transmitted/founder and reservoir viruses. Establishing sensitivity of circulating viruses to bNAbs and genetic patterns affecting neutralization variability may guide rational bNAbs selection for clinical development. We analyzed 326 single env genomes from nine individuals followed longitudinally following acute HIV-1 infection, with samples collected at ~1 week after the first detection of plasma viremia; 300 to 1,709 days postinfection but prior to initiating antiretroviral therapy (ART) (median = 724 days); and ~1 year post ART initiation. Sequences were assessed for phylogenetic relatedness, potential N- and O-linked glycosylation, and variable loop lengths (V1 to V5). A total of 43 env amplicons (median = 3 per patient per time point) were cloned into an expression vector and the TZM-bl assay was used to assess the neutralization profiles of 15 bNAbs targeting the CD4 binding site, V1/V2 region, V3 supersite, MPER, gp120/gp41 interface, and fusion peptide. At 1 μg/mL, the neutralization breadths were as follows: VRC07-LS and N6.LS (100%), VRC01 (86%), PGT151 (81%), 10-1074 and PGT121 (80%), and less than 70% for 10E8, 3BNC117, CAP256.VRC26, 4E10, PGDM1400, and N123-VRC34.01. Features associated with low sensitivity to V1/V2 and V3 bNAbs were higher potential glycosylation sites and/or relatively longer V1 and V4 domains, including known "signature" mutations. The study shows significant variability in the breadth and potency of bNAbs against circulating HIV-1 subtype C envelopes. VRC07-LS, N6.LS, VRC01, PGT151, 10-1074, and PGT121 display broad activity against subtype C variants, and major determinants of sensitivity to most bNAbs were within the V1/V4 domains. IMPORTANCE Broadly neutralizing antibodies (bNAbs) have potential clinical utility in HIV-1 prevention and cure strategies. However, bNAbs target diverse epitopes on the HIV-1 envelope and the virus may evolve to evade immune responses. It is therefore important to identify antibodies with broad activity in high prevalence settings, as well as the genetic patterns that may lead to neutralization escape. We investigated 15 bNAbs with diverse biophysical properties that target six epitopes of the HIV-1 Env glycoprotein for their ability to inhibit viruses that initiated infection, viruses circulating in plasma at chronic infection before antiretroviral treatment (ART), or viruses that were archived in the reservoir during ART in subtype C infected individuals in South Africa, a high burden country. We identify the antibodies most likely to be effective for clinical use in this setting and describe mutational patterns associated with neutralization escape from these antibodies.

A calculated risk: Evaluating HIV resistance to the broadly neutralising antibodies10-1074 and 3BNC117

PURPOSE OF THIS REVIEW

Broadly neutralising antibodies (bNAbs) are a promising new therapy for the treatment of HIV infection. However, the effective use of bNAbs is impacted by the presence of preexisting virological resistance and the potential to develop new resistance during treatment. With several bNAb clinical trials underway, sensitive and scalable assays are needed to screen for resistance. This review summarises the data on resistance from published clinical trials using the bNAbs 10-1074 and 3BNC117 and evaluates current approaches for detecting bNAb sensitivity as well as their limitations.

RECENT FINDINGS

Analyses of samples from clinical trials of 10-1074 and 3BNC117 reveal viral mutations that emerge on therapy which may result in bNAb resistance. These mutations are also found in some potential study participants prior to bNAb exposure. These clinical data are further informed by ex-vivo neutralisation assays which offer an alternative measure of resistance and allow more detailed interrogation of specific viral mutations. However, the limited amount of publicly available data and the need for better understanding of other viral features that may affect bNAb binding mean there is no widely accepted approach to measuring bNAb resistance.

SUMMARY

Resistance to the bNAbs 10-1074 and 3BNC117 may significantly impact clinical outcome following their therapeutic administration. Predicting bNAb resistance may help to lower the risk of treatment failure and therefore a robust methodology to screen for bNAb sensitivity is needed.

Neutralization Sensitivity of HIV-1 CRF07_BC From an Untreated Patient With a Focus on Evolution Over Time

The diversity of HIV-1 envelope (Env) glycoproteins affects the potency and breadth of broadly neutralizing antibodies (bNAbs), a promising alternative to antiretroviral drugs for the prevention and treatment of HIV-1 infection. To facilitate immunogen design and development of therapeutic neutralizing antibodies, we characterized viral evolution and monitored the changes in neutralizing activity/sensitivity of a long-term non-progressor patient with HIV-1 CRF07_BC infection. Fifty-nine full-length Env gene fragments were derived from four plasma samples sequentially harvested from the patient between 2016 and 2020. Sequencing of patient-derived Env genes revealed that potential N-linked glycosylation sites (PNGS) in V1 and V5 significantly increased over time. Further, 24 functional Env-pseudotyped viruses were generated based on Env gene sequences. While all 24 Env-pseudotyped viruses remained sensitive to concurrent and subsequent autologous plasma, as well as bNAbs, including 10E8, VRC01, and 12A21, Env-pseudotyped viruses corresponding to later sampling time were increasingly more resistant to autologous plasma and bNAbs. All 24 Env-pseudotyped viruses were resistant to bNAbs 2G12, PGT121, and PGT135. The neutralization breadth of plasma from all four sequential samples was 100% against the global HIV-1 reference panel. Immune escape mutants resulted in increased resistance to bNAb targeting of different epitopes. Our study identified known mutations F277W in gp41 and previously uncharacterized mutation S465T in V5 which may be associated with increased viral resistance to bNAbs.