Enhanced Ability of Plant-Derived PGT121 Glycovariants To Eliminate HIV-1-Infected Cells

Abstract

The activity of broadly neutralizing antibodies (bNAbs) targeting HIV-1 depends on pleiotropic functions including viral neutralization and the elimination of HIV-1-infected cells. Several in vivo studies have suggested that passive administration of bNAbs represents a valuable strategy for the prevention or treatment of HIV-1. Additionally, different strategies are currently being tested to scale-up the production of bNAbs to obtain the large quantities of antibodies required for clinical trials. Production of antibodies in plants permits low-cost and large-scale production of valuable therapeutics; furthermore, pertinent to this work, it also includes an advanced glycoengineering platform. In this study, we used Nicotiana benthamiana to produce different Fc-glycovariants of a potent bNAb, PGT121, with near-homogeneous profiles and evaluated their antiviral activities. Structural analyses identified a close similarity in overall structure and glycosylation patterns of Fc regions for these plant-derived Abs and mammalian cell-derived Abs. When tested for Fc-effector activities, afucosylated PGT121 showed significantly enhanced FcγRIIIa interaction and antibody dependent cellular cytotoxicity (ADCC) against primary HIV-1-infected cells, both in vitro and ex vivo . However, the overall galactosylation profiles of plant PGT121 did not affect ADCC activities against infected primary CD4+ T cells. Our results suggest that the abrogation of the Fc N-linked glycan fucosylation of PGT121 is a worthwhile strategy to boost its Fc-effector functionality. IMPORTANCE PGT121 is a highly potent bNAb and its antiviral activities for HIV-1 prevention and therapy are currently being evaluated in clinical trials. The importance of its Fc-effector functions in clearing HIV-1-infected cells is also under investigation. Our results highlight enhanced Fc-effector activities of afucosylated PGT121 mAbs that could be important in a therapeutic context to accelerate infected cell clearance and slow disease progression. Future studies to evaluate the potential of plant-produced afucosylated PGT121 in controlling HIV-1 replication in vivo are warranted.

Natural Killer Cells in Antibody Independent and Antibody Dependent HIV Control

“…Antibody binding to CD16 can be modified by glycosylation patterns with afucosylated antibodies having the strongest affinity for CD16 (131,132). There can be regulation of ADCC activity at the effector cell level since there are two major allelic variants of CD16, which are distinguished by a SNP that affects ADCC activity (133,134).…”

Small CD4 mimetics sensitize HIV-1-infected macrophages to antibody-dependent cellular cytotoxicity

“…Being the only viral protein exposed on the surface of infected cells, the HIV-1 Envelope glycoprotein (Env) is the main antigen targeted by neutralizing and non-neutralizing antibodies. Indeed, broadly neutralizing antibodies (bNAbs) have been shown to efficiently mediate Antibody Dependent Cellular Cytotoxicity (ADCC) against productively infected cells (Anand et al, 2021; Bruel et al, 2016; Richard et al, 2018; von Bredow et al, 2016). Most of these studies largely focused on ADCC responses against infected CD4 + T cells.…”