Evaluation of structural conservation and glycan-mediated host receptor engagement of pan-lineage Lassa fusion glycoproteins by cryo-EM

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Project Summary/Abstract: Recognized as a priority emerging pathogen by the World Health Organization due to its potential to cause a public health crisis and the absence of efficacious therapeutics or vaccines,1 Lassa fever affects an estimated 300,000 people per year and results in approximately 5000 deaths.2 Lassa virus (LASV)—a member of the Arenaviridae family—presents heavily glycosylated envelope glycoprotein complexes (GPC) which are the focus of many preclinical vaccine studies. The trimeric conformation of GPC is necessary to induce almost all neutralizing antibody responses in immunization studies3; however, the solubilized ectodomain is inherently unstable and has proved recalcitrant to unbound structural studies in the past.4 Our recent work describes the development of a trimerization scaffold positioned at the membrane proximal region of GPC which stabilizes the protein in its trimeric form. This project will use this platform to describe native-like, representative GPCs from across LASV lineages and structurally explore their interactions with host cell receptors. I hypothesize the high-resolution LASV structures will show conserved epitopes, especially at their receptor-binding regions, which will be used to guide next-generation immunogen design and induce more robust and neutralizing humoral responses. I will test this hypothesis through three primary aims: 1) solving the representative high-resolution, apo structures of LASV GPC across lineages by single- particle cryo-EM, 2) identifying the key residues which facilitate binding with GPC host cell receptors, and 3) developing a suite of stable, soluble GPC trimers representative of clinically relevant LASV strains. I expect the results of these aims will demonstrate conserved GPC epitopes which facilitate neutralizing immune responses will be predominantly quaternary in nature, which has thus far been largely undescribed in the literature due to the instability of the GPC trimer. During this process, I will receive comprehensive training in structural biology, virology, and immunology from my interdisciplinary mentors. The additional professional development resources at the Scripps Research Institute and in the broader San Diego area will ensure I develop the skills needed for my long-term goal of directing a research lab in emerging pathogen vaccine development.