Selection of HIV Envelope Strains for Standardized Assessments of Vaccine-Elicited Antibody-Dependent Cellular Cytotoxicity-Mediating Antibodies

Abstract

Antibody-dependent cellular cytotoxicity (ADCC) has been correlated with reduced risk of HIV-1 infection in several preclinical vaccine trials and the RV144 clinical trial, indicating this is a relevant antibody function to study. Given the diversity of HIV-1, the breadth of vaccine-induced antibody responses is a critical parameter to understand if a universal vaccine is to be realised. Moreover, breadth of ADCC responses can be influenced by different vaccine strategies and regimens, including adjuvants. Therefore, to accurately evaluate ADCC and to compare vaccine regimens, it is important to understand the range of HIV Envelope susceptibility to these responses. These evaluations have been limited because of the complexity of the assay and the lack of a comprehensive panel of viruses for the assessment of these humoral responses. Here, we used twenty-nine HIV-1 infectious molecular clones (IMCs) representing different Envelope subtypes and circulating recombinant forms to characterise susceptibility to ADCC from antibodies in plasma from infected individuals, including thirteen viraemic individuals, ten controllers and six with broadly neutralizing antibody responses. We found in our panel that ADCC susceptibility of the IMCs in our panel did not cluster by subtype, infectivity, level of CD4 downregulation, level of shedding, or neutralization sensitivity. Using partition-around-medoids (PAM) clustering to distinguish smaller groups of IMCs with similar ADCC susceptibility, we identified nested panels of four to eight IMCs that broadly represent the ADCC susceptibility of the entire 29 IMC panel. These panels, together with reagents developed to specifically accommodate circulating viruses at the geographical sites of vaccine trials, will provide a powerful tool to harmonise ADCC data generated across different studies, and detect common themes of ADCC responses elicited by various vaccines. IMPORTANCE Antibody-dependent cellular cytotoxicity (ADCC) responses were found to correlate with reduced risk of infection in the RV144 trial, the only human HIV-1 vaccine to show any efficacy to date. However, reagents to understand the breadth and magnitude of these responses across preclinical and clinical vaccine trials remain underdeveloped. In this study, we characterise HIV-1 infectious molecular clones encoding 29 distinct envelope strains (Env-IMCs) to understand factors which impact virus susceptibility to ADCC and use statistical methods to identify smaller nested panels of four to eight Env-IMCs which accurately represent the full set. These reagents can be used as standardized reagents across studies to fully understand how ADCC may affect efficacy of future vaccine studies, and how studies differed in the breadth of responses developed.

Evolution of Antibody Responses in HIV-1 CRF01_AE Acute Infection: Founder Envelope V1V2 Impacts the Timing and Magnitude of Autologous Neutralizing Antibodies

“…However, IgG levels or subclass did not associate with plasma ADCC activity, indicating that in part, different antibody populations may be mediating these two different plasma antibody functions. This discordance between plasma ADCC and neutralization has been previously demonstrated ( 15 , 77 , 78 ); this relationship may be affected by plasma potency, HIV-1 subtype, and target viral strain. Neutralizing antibodies have been shown to mediate ADCC activity ( 79 ), and ADCC-mediating non-neutralizing antibodies exist.…”

“…CRF01_AE Envs also contains an unusual histidine in the CD4-binding pocket at position 375, potentially leading to potentially greater sampling of the activated Env conformation ( 14 ). However, the incorporation of histidine at position 375 has not been shown to associate with Env antibody-dependent cellular cytotoxicity (ADCC) susceptibility, and these observations may vary by HIV-1 strain ( 15 ). This structural property has been implicated in the development of higher ADCC activity ( 16 – 19 ).…”

A novel HIV triple broadly neutralizing antibody (bNAb) combination-based passive immunization of infant rhesus macaques achieves durable protective plasma neutralization levels and mediates anti-viral effector functions

“…This strategy will reduce the chances of therapy failure due to development of viral resistance, as each antibody will likely target different epitopes on the HIV Env region to induce neutralizing and non-neutralizing functions. In fact, recently, by screening a large panel of HIV variants, it was suggested that viruses rarely develop contemporary resistance to both neutralizing and non-neutralizing antibody functions 42 . In our study, 3/3 and 2/3 bNAbs demonstrated potent neutralizing properties and ADCC functions in vitro , respectively.…”

CD4 downregulation precedes Env expression and protects HIV-1-infected cells from ADCC mediated by non-neutralizing antibodies

“…Several studies reported that cells infected with primary viruses expressing functional Vpu and Nef proteins are resistant to ADCC mediated by CD4i nnAbs, because they maintain surface expressed Env in a "closed" conformation (23, 24, 27, 32-42, 47, 48). Other studies report that CD4i nnAbs can mediate ADCC responses, but they have used infectious molecular clones (IMCs) that are defective for Nef expression (49)(50)(51)(52)(53)(54)(55)(56)(57)(58)(59)(60).…”