Lassa virus glycoprotein nanoparticles elicit a neutralizing antibody that defines a new site of vulnerability

Abstract

Lassa virus is endemic in large parts of West Africa and causes a hemorrhagic fever. Recent years have seen several serious outbreaks of Lassa fever with high mortality rates. A vaccine to curtail infection is urgently needed. The development of a recombinant protein vaccine has been hampered by the instability of soluble Lassa virus gly coprotein complex (GPC) trimers, which disassemble into monomeric subunits after expression. Here we use two - component protein nanoparticles to stabilize GPC in a trimeric conformation and present twenty prefusion GPC trimers on the surface of an icosahedral nanoparticle. Cryo-EM studies of assembled GPC nanoparticles demonstrated a well-ordered structure and yielded a high-resolution structure of an unliganded GPC. These nanoparticles induced potent humoral immune responses in rabbits and protective immunity against a lethal Lassa virus challenge in guinea pigs. We isolated a neutralizing antibody which was mapped to the putative receptor-binding site, revealing a novel site of vulnerability on GPC

Structural conservation of Lassa virus glycoproteins and recognition by neutralizing antibodies

“…As we noticed the GP1-A antibodies shared extensive interaction networks with the apex glycans, we decided to assess whether neutralization by these mAbs is glycan-dependent, as has been seen previously with the NAb LAVA01 (Brouwer et al, 2022). While we observed exceptional interactions of both NAbs with the N89 glycan, previous studies indicate N89 glycan removal leads to cleavage inefficiency.…”

“…To study these antigenic distinctions at a molecular level, we expanded our repertoire of recombinant trimeric GPCs. Our previous work demonstrates the ectodomain of GPC (residues 1-424) from the Josiah strain (lineage IV; LIV) can be stabilized as a trimer by fusion to the two-component self-assembling I53-50 nanoparticle (Bale et al, 2016; Brouwer et al, 2022). Further, this immunogen elicited neutralizing humoral responses in rabbits, suggesting it presents epitopes relevant for neutralization (Brouwer et al, 2022).…”

“…Our previous work demonstrates the ectodomain of GPC (residues 1-424) from the Josiah strain (lineage IV; LIV) can be stabilized as a trimer by fusion to the two-component self-assembling I53-50 nanoparticle (Bale et al, 2016; Brouwer et al, 2022). Further, this immunogen elicited neutralizing humoral responses in rabbits, suggesting it presents epitopes relevant for neutralization (Brouwer et al, 2022). Building off this work, we explore if I53-50A can be used as a trimerization domain to stabilize additional GPCs of diverse lineages.…”

“…Construct design. The LIV GPC monomer, LIV GPC-I53-50A, and Avi-his-tagged LIV GPC-I53-50A constructs were generated as described previously (Brouwer et al, 2022). To generate the NIG08-A41-, Soromba-R, and Togo/2016/7082-GPC-I53-50A constructs, genes encoding GPC residues 1-423 (Genbank: ADU56626.1), 1-424 (Genbank AHC95553.1), and 1-423 (Genbank AMR44577.1), respectively, with the GPCysR4 mutations introduced (Hastie et al, 2017) were cloned by Gibson assembly into PstI-BamHI-digested Josiah-GPC-I53-50A plasmid.…”

“…Published structural information of the GPC in its prefusion conformation is mostly limited to GPC from the lineage IV Josiah strain in complex with antibodies (Enriquez et al, 2022; Hastie et al, 2017, 2019; Katz et al, 2022), although a recent study describes GPC from lineage I (Buck et al). Our recent work demonstrates fusing GPC to the I53-50A component of the computationally designed I53-50 nanoparticle (Bale et al, 2016) stabilized the trimeric conformation of GPC (Brouwer et al, 2022). In line with the generation of I53-50 nanoparticles presenting glycoproteins of HIV-1, SARS-CoV-2, and RSV, GPC-I53-50 nanoparticles assembled efficiently upon mixing of GPC-I53-50A and the pentameric subunit I53-50B (Brouwer et al, 2019, 2021; Marcandalli et al, 2019).…”