Biology subjects

Ollmann Saphire, E.

Publications and source records attributed to Ollmann Saphire, E..

4 recordsLinked to original sources

bioRxiv2021

Molecular assembly of measles and Nipah virus: specific lipid binding drives conformational change and matrix polymerization

Measles virus, Nipah virus, and multiple other paramyxoviruses cause disease outbreaks in humans and animals worldwide. The paramyxovirus matrix (M) protein mediates virion assembly and budding from host cell membranes. M is thus a key target for antivirals, but few high-resolution structures of paramyxovirus M are available, and we lack the clear understanding of how viral M proteins interact with membrane lipids to mediate viral assembly and egress needed to guide antiviral design. Here, we reveal that M proteins associate with phosphatidylserine and phosphatidylinositol-4,5-bisphosphate (PI(4,5)P2) at the plasma membrane. Using X-ray crystallography, electron microscopy, and molecular dynamics we demonstrate that PI(4,5)P2 binding induces conformational and electrostatic changes in the M protein surface that trigger membrane deformation, matrix layer polymerization, and virion assembly.

microbiology↗

bioRxiv2021

Structure selected RBM immunogens prime polyclonal memory responses that neutralize SARS-CoV-2 variants of concern

Successful control of the COVID-19 pandemic depends on vaccines that prevent transmission. The full-length Spike protein is highly immunogenic but the majority of antibodies do not target the virus: ACE2 interface. In an effort to concentrate the antibody response to the receptor-binding motif (RBM) we generated a series of conformationally-constrained immunogens by inserting solvent-exposed RBM amino acid residues into hypervariable loops of an immunoglobulin molecule. Priming C57BL/6 mice with plasmid (p)DNA encoding these constructs yielded a rapid memory response to booster immunization with recombinant Spike protein. Immune sera antibodies bound strongly to the purified receptor-binding domain (RBD) and Spike proteins. pDNA primed for a consistent response with antibodies efficient at neutralizing authentic WA1 virus and two variants of concern (VOC), B.1.351 and B.1.617.2. These findings demonstrate that immunogens built on structure selection can focus the response to conserved sites of vulnerability shared between wildtype virus and VOCs and induce neutralizing antibodies across variants.

immunology↗

bioRxiv2021

Subtle immunological differences in mRNA-1273 and BNT162b2 COVID-19 vaccine induced Fc-functional profiles

The successful development of several COVID-19 vaccines has substantially reduced morbidity and mortality in regions of the world where the vaccines have been deployed. However, in the wake of the emergence of viral variants, able to evade vaccine induced neutralizing antibodies, real world vaccine efficacy has begun to show differences across the mRNA platforms, suggesting that subtle variation in immune responses induced by the BNT162b2 and mRNA1273 vaccines may provide differential protection. Given our emerging appreciation for the importance of additional antibody functions, beyond neutralization, here we profiled the postboost binding and functional capacity of the humoral response induced by the BNT162b2 and mRNA-1273 in a cohort of hospital staff. Both vaccines induced robust humoral immune responses to WT SARS-CoV-2 and VOCs. However, differences emerged across epitopespecific responses, with higher RBD- and NTD-specific IgA, as well as functional antibodies (ADNP and ADNK) in mRNA-1273 vaccine recipients. Additionally, RBD-specific antibody depletion highlighted the different roles of non-RBD-specific antibody effector function induced across the mRNA vaccines, providing novel insights into potential differences in protective immunity generated across these vaccines in the setting of newly emerging VOCs.

immunology↗

bioRxiv2021

Structure-based design of a highly stable, covalently-linked SARS-CoV-2 spike trimer with improved structural properties and immunogenicity

The continued threat of SARS-CoV-2 to global health necessitates development of improved research tools and vaccines. We present an improved SARS-CoV-2 spike ectodomain, "VFLIP", bearing five proline substitutions, a flexible cleavage site linker, and an inter-protomer disulfide bond. VFLIP displays significantly improved stability, high-yield production and retains its trimeric state without exogenous trimerization motifs. High-resolution cryo-EM and glycan profiling reveal that the VFLIP quaternary structure and glycosylation mimic the native spike on the viral surface. Further, VFLIP has enhanced affinity and binding kinetics relative to other stabilized spike proteins for antibodies in the Coronavirus Immunotherapeutic Consortium (CoVIC), and mice immunized with VFLIP exhibit potent neutralizing antibody responses against wild-type and B.1.351 live SARS-CoV-2. Taken together, VFLIP represents an improved tool for diagnostics, structural biology, antibody discovery, and vaccine design.

microbiology↗