Biology subjects

Thorn-Seshold, J.

Publications and source records attributed to Thorn-Seshold, J..

5 recordsLinked to original sources

bioRxiv2023

Prior flavivirus immunity skews the yellow fever vaccine response to expand cross-reactive antibodies with increased risk of antibody dependent enhancement of Zika and dengue virus infection

Human pathogenic flaviviruses pose a significant health concern and vaccination is the most effective instrument to control their circulation. How pre-existing immunity to antigenically related viruses modulates immunization outcome remains poorly understood. In this study, we evaluated the effect of vaccination against tick-borne encephalitis virus (TBEV) on the epitope immunodominance and immunogenicity of the yellow fever 17D vaccine (YF17D) in a cohort of 250 human vaccinees. Following YF17D vaccination, all study participants seroconverted and generated protective neutralizing antibody titers. At day 28, TBEV pre-immunity did not affect the polyclonal neutralizing response which largely depended on the IgM fraction. We found that sera from TBEV-immunized individuals enhanced YF17D vaccine virus infection via antibody-dependent enhancement (ADE). Upon vaccination, individuals with TBEV pre-immunity had higher concentrations of cross-reactive IgG antibodies with limited neutralizing capacity against YF17D whereas vaccinees without prior flavivirus exposure showed a non-cross-reacting response. Using a set of recombinant YF17D envelope protein mutants displaying different epitopes, we identified quaternary epitopes as the primary target of neutralizing antibodies. Sequential immunizations redirected the IgG response towards the pan-flavivirus fusion loop epitope (FLE) with the potential to mediate enhancement of dengue and Zika virus infections whereas TBEV naive individuals elicited an IgG response directed towards neutralizing epitopes without an enhancing effect. We propose that the YF17D vaccine effectively conceals the FLE and primes a neutralizing IgG response in individuals with no prior flavivirus exposure. In contrast, the response in TBEV-experienced recipients favors weakly-neutralizing, cross-reactive epitopes potentially increasing the risk of severe dengue and Zika disease due to ADE.

immunology↗

bioRxiv2022

Cyclic dichalcogenides extend the reach of bioreductive prodrugs to harness the thioredoxin system: applications to seco-duocarmycins

Small molecule prodrug approaches that can activate cancer therapeutics selectively in tumors are urgently needed. Here, we developed the first antitumor prodrugs designed for activation by the thioredoxin (Trx) oxidoreductase system. This critical cellular disulfide redox axis is tightly linked to dysregulated redox/metabolic states in cancer, yet it cannot be addressed by current bioreductive prodrugs, which mainly cluster around oxidised nitrogen species. We instead harnessed Trx/TrxR-specific artificial dichalcogenides to gate the bioactivity of a series of 10 "off-to-on" reduction-activated duocarmycin prodrugs. The prodrugs were tested for cell-free and cellular activity dependent on reducing enzyme systems in 177 cell lines, to establish broad trends for redox-based cellular bioactivity of the dichalcogenides. They were well tolerated in vivo in mice, indicating low systemic release of their duocarmycin cargo, and in vivo anti-tumor efficacy trials in mouse models of breast and pancreatic cancer gave promising initial results indicating effective tumoral drug release, presumably by in situ bioreductive activation. This work therefore presents a chemically novel class of bioreductive prodrugs against a previously unaddressed reductase type, validates its ability to access in vivo compatible small-molecule prodrugs even of potently cumulative toxins, and so introduces carefully tuned dichalcogenides as a platform strategy for specific bioreduction-based release.

biochemistry↗

bioRxiv2021

A high-throughput neutralization assay for yellow fever serodiagnostics

Quick and accurate detection of neutralizing antibodies (nAbs) against yellow fever is essential in serodiagnosis during outbreaks, for surveillance and to evaluate vaccine efficacy in population-wide studies. All this requires serological assays that can process a large number of samples in a highly standardized format. Albeit being laborious, time-consuming and limited in throughput, classical plaque reduction neutralization test (PRNT) is still considered gold standard for the detection and quantification of nAbs due to its sensitivity and specificity. Here we report the development of an alternative fluorescence-based serological assay (SNTFLUO) with an equally high sensitivity and specificity that is fit for high-throughput testing with the potential for automation. Finally, our novel SNTFLUO was cross-validated in several reference laboratories and against international WHO standards showing its potential to be implemented in clinical use. SNTFLUO assays with similar performance are available for the Japanese encephalitis, Zika and dengue viruses amenable for differential diagnostics. IMPORTANCEFast and accurate detection of neutralizing antibodies (nAbs) against yellow fever virus (YFV) is key in yellow fever serodiagnosis, outbreak surveillance and monitoring of vaccine efficacy. Although classical PRNT still remains gold standard for measuring YFV nAbs, this methodology suffers from inherent limitations such as a low throughput and an overall high labor intensity. We present a novel fluorescence-based serum neutralization test (SNTFLUO) with equally high sensitivity and specificity that is fit for processing large number of samples in a highly standardized manner and has the potential to be implemented in clinical use. In addition, we present SNTFLUO assays with similar performance for Japanese encephalitis, Zika and dengue viruses opening new avenues for differential diagnostics.

microbiology↗

bioRxiv2021

Photoswitchable epothilone-based microtubule stabilisers allow GFP imaging-compatible, optical control over the microtubule cytoskeleton

Optical methods to modulate microtubule stability and dynamics are promising approaches to reach the micron- and millisecond-scale resolution needed to decrypt the diverse roles of the microtubule cytoskeleton in biology. However, such optical methods have until now focussed nearly exclusively on microtubule destabilisation. Here, we introduce "STEpos" as light-responsive epothilone reagents, designed to photoswitchably bind to tubulin and stabilise lateral contacts in the microtubule lattice. Using a novel styrylthiazole photoswitch, designed to allow the hydrogen-bonding that is key to epothilone potency, we have created the first set of GFP-orthogonal photoswitchable microtubule stabilisers. The STEpos can photocontrol microtubule polymerisation, cell division, and cellular microtubule dynamics with micron- and second-scale spatiotemporal precision. STEpos offer substantial improvements of potency, solubility, and ease-of-use compared to the only previous photopharmaceuticals for microtubule stabilisation. The intriguing structure-photoswitching-activity relationship insights from this work will also assist future developments of improved STEpo reagents, and we anticipate that these will contribute greatly to high-precision cytoskeleton research across the fields of biophysics, cargo transport, cell motility, cell division, development, and neuroscience.

cell biology↗

bioRxiv2021

In vivo photocontrol of microtubule dynamics and integrity, migration and mitosis, by the potent GFP-imaging-compatible photoswitchable reagents SBTubA4P and SBTub2M

Photoswitchable reagents to modulate microtubule stability and dynamics are an exciting tool approach towards micron- and millisecond-scale control over endogenous cytoskeleton-dependent processes. When these reagents are globally administered yet locally photoactivated in 2D cell culture, they can exert precise biological control that would have great potential for in vivo translation across a variety of research fields and for all eukaryotes. However, photopharmacologys reliance on the azobenzene photoswitch scaffold has been accompanied by a failure to translate this temporally- and cellularly-resolved control to 3D models or to in vivo applications in multi-organ animals, which we attribute substantially to the metabolic liabilities of azobenzenes. Here, we optimised the potency and solubility of metabolically stable, druglike colchicinoid microtubule inhibitors based instead on the styrylbenzothiazole (SBT) photoswitch scaffold, that are non-responsive to the major fluorescent protein imaging channels and so enable multiplexed imaging studies. We applied these reagents to 3D systems (organoids, tissue explants) and classic model organisms (zebrafish, clawed frog) with one- and two-protein imaging experiments. We successfully used systemic treatment plus spatiotemporally-localised illuminations in vivo to photocontrol microtubule dynamics, network architecture, and microtubule-dependent processes in these systems with cellular precision and second-level resolution. These nanomolar, in vivo-capable photoswitchable reagents can prove a game-changer for high-precision cytoskeleton research in cargo transport, cell motility, cell division and development. More broadly, their straightforward design can also inspire the development of similarly capable optical reagents for a range of protein targets, so bringing general in vivo photopharmacology one step closer to productive realisation.

cell biology↗