Biology subjects

Schendel, S. L.

Publications and source records attributed to Schendel, S. L..

5 recordsLinked to original sources

bioRxiv2023

Intracellular Ebola Virus nucleocapsid assembly revealed by in situ cryo-electron tomography.

Filoviruses, including Ebola and Marburg viruses, cause hemorrhagic fevers with up to 90% lethality. The viral nucleocapsid is assembled by polymerization of the nucleoprotein (NP) along the viral genome, together with the viral proteins VP24 and VP35. We employed cryo-electron tomography of cells transfected with viral proteins and infected with model Ebola virus, to illuminate assembly intermediates as well as a 9[A] map of the complete intracellular assembly. This structure reveals a previously unresolved, third, and outer layer of NP complexed with VP35. The intrinsically-disordered-region together with the C-terminal domain of this outer layer of NP provides the constant-width between intracellular nucleocapsid bundles and likely functions as a flexible tether to the viral matrix protein in virion. A comparison of intracellular nucleocapsid with prior in-virion nucleocapsid structures reveals the nucleocapsid further condenses vertically in-virion. The interfaces responsible for nucleocapsid assembly are highly conserved and offer targets for broadly effective antivirals.

microbiology↗

bioRxiv2022

Structure of the Inmazeb cocktail and resistance to escape against Ebola virus

Monoclonal antibodies can provide important pre- or post-exposure protection against disease for those not yet vaccinated or in individuals that fail to mount a protective immune response after vaccination. A key concern in use of monotherapy monoclonal antibody products lies in the high risk of mutagenic escape. Inmazeb (REGN-EB3), a three-antibody cocktail against Ebola virus, demonstrated efficacy in lessening disease course and improving survival in a randomized, controlled trial. Here we present the cryoEM structure at 3.1 [A] of the Ebola virus glycoprotein, determined without symmetry averaging, in a simultaneous complex with eight Fab fragments of antibodies in the Inmazeb cocktail. This structure allows modeling of previously disordered portions of the glycan cap, maps the non-overlapping epitopes of Inmazeb, and illuminates the basis for complementary activities, as well as residues that are critical for resistance to escape by each component of this cocktail and other clinically relevant antibodies. We also provide direct evidence that, unlike monotherapy treatments, including those targeting conserved epitopes, the Inmazeb protects against the rapid emergence of EBOV escape mutants and supports the benefit of the combination approach.

biophysics↗

bioRxiv2022

Structural basis for antibody-mediated neutralization of Lymphocytic choriomeningitis virus

The mammarenavirus Lymphocytic choriomeningitis virus (LCMV) is a globally distributed zoonotic pathogen that can be lethal in immunocompromised patients and cause severe birth defects if acquired during pregnancy. Despite the fundamental importance of LCMV for studying immunobiology, the structure of the trimeric surface glycoprotein, essential for entry, vaccine design and antibody neutralization, remains unknown. In this study, we present the cryoEM structure of the LCMV surface glycoprotein (GP) in its trimeric prefusion assembly both alone and in complex with a rationally engineered monoclonal neutralizing antibody termed 18.5C-M28 (M28). Additionally, we show that passive administration of M28 protects mice from LCMV clone 13 (LCMVcl13) challenge when administered as either a prophylactic or therapeutic. Our study illuminates not only the overall structural organization of LCMV GP and the mechanism for its inhibition by M28, but also presents a promising therapeutic candidate to prevent severe or fatal disease in individuals who are at risk of infection by a virus that poses a threat worldwide. HighlightsO_LIRationally-engineered antibody M28 neutralizes lymphocytic choriomeningitis virus in vitro. C_LIO_LIFirst high-resolution cryoEM structure of the pre-fusion trimeric lymphocytic choriomeningitis virus glycoprotein alone and in complex with M28. C_LIO_LIM28 neutralizes by bridging adjacent glycoprotein protomers and locking it in the pre-fusion state. C_LIO_LIProphylactic and therapeutic administration of M28 protects mice from chronic lymphocytic choriomeningitis virus infection. C_LI

microbiology↗

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-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↗