Blockage of CD59 Function Restores Activities of Neutralizing and Nonneutralizing Antibodies in Triggering Antibody-Dependent Complement-Mediated Lysis of HIV-1 Virions and Provirus-Activated Latently Infected Cells

Abstract

Both HIV-1 virions and infected cells use their surface regulators of complement activation (RCA) to resist antibody-dependent complement-mediated lysis (ADCML). Blockage of the biological function of RCA members, particularly CD59 (a key RCA member that controls formation of the membrane attack complex at the terminal stage of the complement activation cascades via all three activation pathways), has rendered both HIV-1 virions and infected cells sensitive to ADCML mediated by anti-Env antibodies (Abs) or sera/plasma from patients at different stages of viral infection. In the current study, we used the well-characterized anti-HIV-1 neutralizing Abs (nAbs), including 2G12, 2F5, and 4E10, and non-nAbs, including 2.2C, A32, N5-i5, and N12-i15, to investigate whether the enhancement of ADCML by blockage of CD59 function is mediated by nAbs, non-nAbs, or both. We found that all nAbs and two non-nAbs (N5-i5 and A32) strongly reacted to three HIV-1 laboratory strains (R5, X4, and R5/ X4), six primary isolates, and provirus-activated ACH-2 cells examined. In contrast, two non-nAbs, 2.2C and N12-i15, reacted weakly and did not react to these targets, respectively. After blockage of CD59 function, the reactive Abs, regardless of their neutralizing activities, significantly enhanced specific ADCML of HIV-1 virions (both laboratory strains and primary isolates) and provirus-activated latently infected cells. The ADMCL efficacy positively correlated with the enzyme-linked immunosorbent assay-reactive intensity of those Abs with their targets. Thus, blockage of RCA function represents a novel approach to restore activities of both nAbs and non-nAbs in triggering ADCML of HIV-1 virions and provirus-activated latently infected cells. IMPORTANCEThere is a renewed interest in the potential role of non-nAbs in the control of HIV-1 infection. Our data, for the first time, demonstrated that blockage of the biological function of RCA members rendered both HIV-1 virions and infected cells sensitive to ADCML mediated by not only nAbs but also non-nAbs. Our results are significant in developing novel immune-based approaches to restore the functions of nAbs and non-nAbs in the circulation of HIV-1-infected individuals to specifically target and clear HIV-1 virions and infected cells. Our data also provide new insights into the mechanisms by which HIV-1 virions and infected cells escape Ab-mediated immunity and could aid in the design and/or development of therapeutic HIV-1 vaccines. In addition, a combination of antiretroviral therapy with RCA blockage, provirus activators, and therapeutic vaccines may represent a novel approach to eliminate HIV-1 reservoirs, i.e., the infected cells harboring replication-competent proviruses and residual viremia.

Anti‐HIV‐1 antibodies trigger non‐lytic complement deposition on infected cells

“…We did not observe a rapid death of infected lymphocytes mediated by the complement pathway, even when the cells were opsonized by C3 and MAC. Knockout of CD59 by CRISPR-Cas9 restored sensitivity to killing, confirming previous results obtained with blocking anti-CD59 antibodies [40,41]. We further report that this non-lytic complement deposition leads to an accelerated disappearance of infected cells within a few days of culture.…”

“…Knockout of CD59 by CRISPR-Cas9 restored sensitivity to killing, confirming previous results obtained with blocking anti-CD59 antibodies [40,41]. Knockout of CD59 by CRISPR-Cas9 restored sensitivity to killing, confirming previous results obtained with blocking anti-CD59 antibodies [40,41].…”

Natural killer cells in HIV-1 infection and therapy

“…The Fc-regions of IgG1 and IgG3 antibodies represent human isotopes able to regulate both ADCC and antibody-mediated complement-mediated lysis (ADCML). Both bNAbs non-bNAbs can eliminate HIV-1 virions as well as infected cells via ADCC and ADCML [161]. In particular, the binding of C3 complement protein on target cells in HIV-1 infection in vitro has been show to increase NK cell-mediated ADCC cytotoxicity [162].…”

CD59 association with infectious bronchitis virus particles protects against antibody-dependent complement-mediated lysis

“…Functional inhibition of CD59 reportedly restores the activities of neutralizing and non-neutralizing antibodies in initiating the ADCML of HIV-1 virions and provirusactivated, latently infected cells [12]. Thus, we abolished CD59 function by its blocker and PI-PLC cleavage, and determined the sensitivity of IBV virions to ADCML.…”

“…In some enveloped viruses, such as influenza virus, human cytomegalovirus, Ebola virus, human immunodeficiency virus-1 (HIV-1) and herpes simplex virus-1, viral envelopes associate with host complement regulators to escape ADCML [8][9][10][11][12]. Coronavirus infectious bronchitis virus (IBV) is an enveloped, positive-sense, single-stranded RNA virus that belongs to the family Coronaviridae [13], along with severe acute respiratory syndrome coronavirus and Middle East respiratory syndrome coronavirus [14].…”