Biology subjects

Niewiesk, S.

Publications and source records attributed to Niewiesk, S..

7 recordsLinked to original sources

bioRxiv2025

Stabilized Full-Length Measles Fusion Protein Elicits Potent Immunity and Protection In Vivo

Measles virus (MeV) is a highly contagious pathogen that causes significant morbidity and mortality in populations with low vaccination coverage. Infection typically leads to immune amnesia and, in rare cases, fatal neurological disease. While current live-attenuated vaccines are highly effective, they primarily elicit neutralizing antibodies against the hemagglutinin (H) glycoprotein, with a less robust response to the fusion (F) protein, a key protein for viral entry. To improve the immunogenicity of the F protein, we designed and characterized stabilized, prefusion MeV F protein antigens. We engineered both soluble ectodomains (FECTO) and full-length, membrane-embedded proteins (FFL) with mutations that confer thermal stability. Cryo-electron microscopy confirmed that these engineered antigens faithfully maintain the native prefusion conformation. When evaluated in a cotton rat model, immunization with either FECTO or FFL constructs induced neutralizing antibodies and elicited protection against viral challenge. The most stable full-length construct (FFL 3M) elicited a more potent neutralizing antibody response than its ectodomain counterpart. Importantly, no evidence of vaccine-enhanced respiratory disease was observed. These findings establish that a thermostable, full-length F protein is a superior immunogen to its soluble ectodomain. This work presents a promising candidate for next-generation, non-replicating measles vaccines intended to complement current vaccination strategies and provide a safe option for immunocompromised individuals and others who cannot receive live-virus vaccines. One-Sentence SummaryA prefusion-stabilized, full-length measles Fusion glycoprotein immunogen induces strong neutralizing responses and offers protection against challenge with wild-type virus.

immunology↗

bioRxiv2025

Structural and Mechanistic Basis for Antibody Neutralization of the Measles Fusion Protein

Measles virus (MeV) is a highly contagious viral pathogen and remains a major global health threat. Resurgent infections, driven by insufficient vaccine coverage, waning herd immunity, and the vulnerability of immunocompromised individuals, highlight the urgent need for effective countermeasures. Monoclonal antibodies (mAbs) represent a promising strategy, both as antiviral agents and as probes of viral entry mechanisms. While most vaccine-elicited neutralizing antibodies target the hemagglutinin (H) protein, emerging evidence suggests that antibodies against the fusion (F) protein are also potent inhibitors. Still, there is insufficient information on the target sites and activities of antibodies against the F protein. Like other class I fusion proteins, MeV F exists in a metastable prefusion state that undergoes dramatic conformational changes during viral entry. Here, we selected four mAbs that recognize conformational patterns of F-prefusion and/or postfusion, characterized their epitopes, specificities, and antiviral activities. Structural analyses mapped antibody interactions onto pre- and postfusion F conformations, revealing that all three neutralizing mAbs are specific for the prefusion form, while the non-neutralizing mAb recognizes only the postfusion F. Biophysical and functional assays defined distinct mechanisms: neutralization occurs either by stabilizing the prefusion protein or by preventing the extended intermediate from completing fusion. We also describe a novel mechanism of neutralization in which an antibody prematurely triggers F activation but blocks the subsequent refolding required for viral entry. Together, these findings provide the first detailed mapping of neutralizing epitopes on the MeV F protein and establish a framework for the rational design of F-targeted intervention.

immunology↗

bioRxiv2025

Uncovering the features of Measles-targeting human antibodies elicited by the MMR vaccine

Measles virus (MeV), a highly transmissible paramyxovirus, causes disease that can lead to severe complications and death, particularly in babies and young children. Deployment of the durable, highly effective, live-attenuated measles vaccine has saved an estimated 94 million lives in the past 50 years,1 yet the immunological explanation for this vaccines unique success and its landscape of antibody recognition remains unclear. Here we report the first panel of human monoclonal antibodies (mAbs) specific for the MeV hemagglutinin (H) and fusion (F) surface proteins, derived from the memory B cells of an MMR vaccinee. From over 100 cloned human mAbs, we mapped four major epitope clusters on H and another five major clusters on F, and structurally characterized 17 representative mAbs including one or more examples of each of the nine epitope clusters on the two surface antigens. We find that antibodies against both H and F can lead to potent virus neutralization and reduction of viral loads in vivo, including one mAb against F that reduces viral loads to below the limit of detection for all animals. High-resolution cryo-EM reveals contact sites of the most protective antibodies against both surface antigens. Discovery, characterization, and in vitro and in vivo success of these fully human mAbs now provide new avenues for prophylactic or therapeutic intervention against this re-emerging virus. HighlightsO_LIA large panel of Measles-specific monoclonal antibodies was isolated from a human MMR vaccinee, years after vaccination. C_LIO_LIStructural and biochemical mapping paints a landscape of antibody recognition with nine major competition groups, including four major sites on Hemagglutinin (H) and five on the fusion protein (F). C_LIO_LIAntibodies against both H and F confer in vitro neutralization and in vivo protection, including, in one case, undetectable viral load after antibody treatment. C_LIO_LIThe most protective H-specific mAbs, 4D08 and 1C08, target the receptor-binding site and the F-proximal outside of the H dimer, and likely function by interfering with receptor binding and H-F interactions, respectively. C_LIO_LIThe most protective F-specific mAbs, 3A12 and 4F09, target the sides and apex of the prefusion F trimer, and likely function by locking F into its pre-fusion state C_LI

immunology↗

bioRxiv2024

A chromosome-level genome assembly of the Hispid cotton rat (Sigmodon hispidus), a model for human pathogenic virus infections

BackgroundThe cotton rat (Sigmodon hispidus), a rodent species native to the Americas, has emerged as a valuable laboratory model of infections by numerous human pathogens including poliovirus and respiratory syncytial virus (RSV). ResultsHere we report the first reference assembly of the cotton rat genome organized at a chromosomal level, providing annotation of 24,878 protein-coding genes. Data from PCR-free whole genome sequencing, linked-read sequencing and RNA sequencing from pooled cotton rat tissues were analyzed to assemble and annotate this novel genome sequence. Spectral karyotyping data using fluorescent probes derived from mouse chromosomes facilitated the assignment of cotton rat orthologs to syntenic chromosomes, comprising 25 autosomes and a sex chromosome in the haploid genome. Comparative phylome analysis revealed both gains and losses of numerous genes including immune defense genes against pathogens. We identified thousands of recently retrotransposed L1 and SINE B2 elements, revealing widespread genetic innovations unique to this species. ConclusionsWe anticipate that annotation and characterization of the first chromosome-level cotton rat genome assembly as described here will enable and accelerate ongoing investigations into its host defenses against viral and other pathogens, genome biology and mammalian evolution.

genomics↗

bioRxiv2021

Engineering protease-resistant peptides to inhibit human parainfluenza viral respiratory infection

The lower respiratory tract infections affecting children worldwide are in large part caused by the parainfluenza viruses (HPIVs), particularly HPIV3, along with human metapneumovirus and respiratory syncytial virus, enveloped negative-strand RNA viruses. There are no vaccines for these important human pathogens, and existing treatments have limited or no efficacy. Infection by HPIV is initiated by viral glycoprotein-mediated fusion between viral and host cell membranes. A viral fusion protein (F), once activated in proximity to a target cell, undergoes a series of conformational changes that first extend the trimer subunits to allow insertion of the hydrophobic domains into the target cell membrane, and then refold the trimer into a stable postfusion state, driving the merger of the viral and host cell membranes. Lipopeptides derived from the C-terminal heptad repeat (HRC) domain of HPIV3 F inhibit infection by interfering with the structural transitions of the trimeric F assembly. Clinical application of this strategy, however, requires improving the in vivo stability of antiviral peptides. We show that the HRC peptide backbone can be modified via partial replacement of -amino acid residues with {beta}-amino acid residues to generate /{beta}-peptides that retain antiviral activity but are poor protease substrates. Relative to a conventional -lipopeptide, our best /{beta}-lipopeptide exhibits improved persistence in vivo and improved anti-HPIV3 antiviral activity in animals.

microbiology↗

bioRxiv2018

Mathematical Modeling Identifies the Role of Adaptive Immunity as a Key Controller of Respiratory Syncytial Virus (RSV) Titer in Cotton Rats

Respiratory syncytial virus (RSV) is a common virus that can have varying effects ranging from mild cold-like symptoms to mortality depending on the age and immune status of the individual. We combined mathematical modeling using ordinary differential equations (ODEs) with measurement of RSV infection kinetics in primary well differentiated human airway epithelial (HAE) cultures in vitro and in immunocompetent and immunosuppressed cotton rats to glean mechanistic details that underlie RSV infection kinetics in the lung. Quantitative analysis of viral titer kinetics in our mathematical model showed that the elimination of infected cells by the adaptive immune response generates unique RSV titer kinetic features including a faster time scale of viral titer clearance than viral production, and a monotonic decrease in the peak RSV titer with decreasing inoculum dose. Parameter estimation in the ODE model using a non-linear mixed effects approach revealed a very low rate (average single cell lifetime > 10 days) of cell lysis by RSV before the adaptive immune response is initiated. Our model predicted negligible changes in the RSV titer kinetics on earlier days (< 5 d.p.i) but a slower decay in RSV titer at later days (>5 d.p.i) in immunosuppressed cotton rats compared to that in non-suppressed cotton rats in silico. These predictions were in excellent agreement with the experimental results. Our combined approach quantified the importance of the adaptive immune response in suppressing RSV infection in cotton rats, which could be useful in testing RSV vaccine candidates.\n\nImportanceA major difficulty in developing vaccines against RSV infection is our rudimentary understanding of the mechanisms that underlie RSV infection. We addressed this challenge by developing a mechanistic computational model with predictive powers for describing RSV infection kinetics in cotton rats. The model was constructed synergistically with in vitro and in vivo measurements. The combined framework determined an important role for CD8+ T cells responses in reducing RSV titers in cotton rats. The framework can be used to design future experiments to elucidate mechanisms underlying RSV infection and test outcomes for potential vaccine candidates. In addition, estimation of the model parameters provides quantitative values for parameters of biological and clinical interest such as the replication rate of RSV, the death rate of infected cells, and the average number of new infections initiated by a single infected cell.

microbiology↗

bioRxiv2018

Mathematical Modeling Identifies the Role of Adaptive Immunity as a Key Controller of Respiratory Syncytial Virus (RSV) Titer in Cotton Rats

Respiratory syncytial virus (RSV) is a common virus that can have varying effects ranging from mild cold-like symptoms to mortality depending on the age and immune status of the individual. We combined mathematical modeling using ordinary differential equations (ODEs) with measurement of RSV infection kinetics in primary well differentiated human airway epithelial (HAE) cultures in vitro and in immunocompetent and immunosuppressed cotton rats to glean mechanistic details that underlie RSV infection kinetics in the lung. Quantitative analysis of viral titer kinetics in our mathematical model showed that the elimination of infected cells by the adaptive immune response generates unique RSV titer kinetic features including a faster time scale of viral titer clearance than viral production, and a monotonic decrease in the peak RSV titer with decreasing inoculum dose. Parameter estimation in the ODE model using a non-linear mixed effects approach revealed a very low rate (average single cell lifetime > 10 days) of cell lysis by RSV before the adaptive immune response is initiated. Our model predicted negligible changes in the RSV titer kinetics on earlier days (< 5 d.p.i) but a slower decay in RSV titer in immunosuppressed cotton rats compared to that in non-suppressed cotton rats at later days (>5 d.p.i) in silico. These predictions were in excellent agreement with the experimental results. Our combined approach quantified the importance of the adaptive immune response in suppressing RSV infection in cotton rats, which could be useful in testing RSV vaccine candidates.\n\nImportanceA major difficulty in developing vaccines against RSV infection is our rudimentary understanding of the mechanisms that underlie RSV infection. We addressed this challenge by developing a mechanistic computational model with predictive powers for describing RSV infection kinetics in cotton rats. The model was constructed synergistically with in vitro and in vivo measurements. The combined framework determined an important role for CD8+ T cells responses in reducing RSV titers in cotton rats. The framework can be used to design future experiments to elucidate mechanisms underlying RSV infection and test outcomes for potential vaccine candidates. In addition, estimation of the model parameters provides quantitative values for parameters of biological and clinical interest such as the replication rate of RSV, the death rate of infected cells, and the average number of new infections initiated by a single infected cell.

microbiology↗