Signal Peptide of HIV-1 Envelope Modulates Glycosylation Impacting Exposure of V1V2 Epitopes

Abstract

AbstractHIV-1 envelope (Env) is a trimer of gp120-gp41 heterodimers, synthesized from a precursor gp160 that contains an ER-targeting signal peptide (SP) at its amino-terminus. Each trimer is swathed by ∼90 N-linked glycans, comprising complex-type and oligomannose-type glycans, which play an important role in determining virus sensitivity to neutralizing antibodies. We previously examined the effects of single point SP mutations on Env properties and functions. Here, we aimed to understand the impact of the SP diversity on glycosylation of virus-derived Env and virus neutralization by swapping SPs. Analyses of site-specific glycans revealed that SP swapping altered Env glycan content and occupancy on multiple N-linked glycosites, including the conserved N156 and N160 glycans in the V1V2 region at the Env trimer apex. Virus neutralization was also affected, especially by antibodies against the V2i, V2p and V2q epitopes. Likewise, SP swaps affected the recognition of soluble and cell-associated Env by antibodies targeting distinct V1V2 configurations. These data highlight the contribution of SP sequence diversity in shaping the Env glycan content and its impact on the configuration and accessibility of V1V2 epitopes on Env.Author SummaryHIV-1 Env glycoprotein is produced by a precursor gp160 that has a signal peptide at its N-terminus. The SP is highly diverse among the HIV-1 isolates and no two SP are same. This study presents site-specific analyses of N-linked glycosylation on HIV-1 envelope glycoproteins from infectious viruses produced with different envelope signal peptides. We show that signal peptide swapping alters the envelope glycan shield, including the conserved N156 and N160 located in the V1V2 region on the trimer apex, to impact Env recognition and virus neutralization by antibodies, particularly those targeting the the V1V2 region. The data offer crucial insights into the role of signal peptide in the interplay between HIV-1 and antibodies and its potential utility to control Env glycosylation in the development of Env-based HIV-1 vaccine.