Biology subjects

Schoen, J.

Publications and source records attributed to Schoen, J..

11 recordsLinked to original sources

bioRxiv2026

In Vitro Fertilization using Magnetotactic Sperm Cells

In vitro fertilization (IVF) is essential for many couples facing infertility, e.g. in cases of low sperm count (oligospermia), where natural fertilization is unlikely. Medical microrobotics, making use of microscopic devices designed to perform targeted tasks inside the body under imaging guidance and controlled actuation, represents a promising strategy to guide sperm cells toward the oocyte. This approach may significantly reduce the time, invasiveness, and patient burden of conventional IVF, with long-term potential for in vivo assisted reproduction. Here, we report the first successful in vitro fertilization (IVF) using magnetically functionalized spermatozoa, termed magnetotactic sperm cells (MSCs), as a step toward in vivo microrobotic guidance of sperm cells for targeted artificial insemination. We present a protocol for the preparation of MSCs for their use in IVF, resulting in samples largely free of non-functionalized sperm cells (99.69% purity). We systematically evaluate the effect of particle functionalization on sperm health, including acrosome integrity, DNA fragmentation, mitochondrial membrane potential, oxidative stress, and epithelial interactions, and observe no adverse effects. Notably, MSCs showed improved mitochondrial membrane integrity compared to the control samples after two hours of incubation. Using MSCs, we successfully performed complete IVF cycles that resulted in embryos developing to the blastocyst stage at a comparable rate as non-functionalized sperm cells of the same concentration. Lower concentrations of non-functionalized sperm cells (comparable to those remaining in the MSC sample after purification) did not result in any development of embryos to blastocysts. To facilitate manipulation and translation, we implemented automated image-based recognition, magnetic manipulation, and pre-clustering routines that increased guidance efficiency and are compatible with standard IVF workflows. Together, these results demonstrate that magnetic functionalization can be applied without compromising key sperm quality metrics and can enable directed sperm guidance for assisted oocyte fertilization. This work provides a practical framework for integrating microrobotic sperm manipulation into assisted-reproduction workflows and supports further development toward automated in vitro and eventual in vivo applications.

bioengineering↗

bioRxiv2026

One and Done: A safe, adaptable single-cycle SARS-CoV-2 vaccine platform blocks XBB.1.5 infection and transmission

A next-generation SARS-CoV-2 vaccine must address the currently inadequate prevention of virus transmission, particularly against emerging variants of concern, a challenge that none of the licensed commercial vaccines fully meet. Effective control of respiratory pandemics necessitates vaccines that 1) can be rapidly adapted, 2) have high patient compliance with simple and non-invasive administration, and 3) block transmission in a virus challenge. We describe here the characterization of an updated single-cycle SARS-CoV-2 vaccine candidate (scVac), engineered as a replication-defective virus with targeted deletions of the E gene and ORF6 and ORF7a, along with a truncation of ORF3a. The candidate carries an Omicron XBB.1.5 Spike (scVacXBB), maintaining all essential antigenic properties. The vaccine demonstrated an excellent safety profile in K18-hACE2 transgenic mice, the most sensitive virulence model, with no clinical signs or adverse events observed. In the Syrian hamster model, potent systemic and mucosal immune responses were induced, along with a strong neutralizing antibody response. Notably, there was no virus transmission to co-housed naive animals, which outperforms a bivalent Omicron mRNA vaccine reference. Our results demonstrate that scVacXBB-induced immunity not only prevents disease but also effectively blocks transmission. Furthermore, the successful introduction of the XBB.1.5 Spike protein into the scVac platform demonstrates the pipelines ability to adapt quickly to any emerging variant. These findings highlight the potential of this single-cycle concept as a next-generation COVID-19 vaccine, offering robust protection with a strong safety profile.

immunology↗

bioRxiv2025

Quantitative phase deformability cytometry (QP-DC) for precise and clinically relevant multiparametric immune cell profiling

Imaging flow cytometry enables the detailed analysis of cell morphology and internal structures through high-throughput cell imaging, and quantitative phase imaging (QPI)-based microfluidic approaches have extended this by providing label-free measures such as dry mass and refractive index (RI). Building on these developments, we present quantitative phase deformability cytometry (QP-DC), which integrates QPI with deformability cytometry to simultaneously measure morphology, mechanics, and intrinsic biophysical parameters such as mass density and dry mass. Numerical refocusing ensures in-focus images independent of axial position, improving precision in contour detection and feature extraction. Using microspheres and whole blood, we validated QP-DC and then applied it to neutrophils under lipopolysaccharide (LPS) stimulation and from patients with systemic lupus erythematosus (SLE). QP-DC revealed LPS-induced reductions in neutrophil mass density and identified heterogeneous subpopulations in SLE. These results demonstrate the capability of QP-DC for precise biophysical and mechanical characterization, offering significant potential for research and clinical diagnostics.

biophysics↗

bioRxiv2024

Outcome of H5N1 clade 2.3.4.4b virus infection in calves and lactating cows

In March 2024, highly pathogenic avian influenza virus (HPAIV) clade 2.3.4.4b H5N1 infections in dairy cows were first reported from Texas, USA. Rapid dissemination to more than 190 farms in 13 states followed. Here, we provide results of two independent clade 2.3.4.4b experimental infection studies evaluating (i) oronasal susceptibility and transmission in calves to a US H5N1 bovine isolate genotype B3.13 (H5N1 B3.13) and (ii) susceptibility of lactating cows following direct mammary gland inoculation of either H5N1 B3.13 or a current EU H5N1 wild bird isolate genotype euDG (H5N1 euDG). Inoculation of the calves resulted in moderate nasal replication and shedding with no severe clinical signs or transmission to sentinel calves. In dairy cows, infection resulted in no nasal shedding, but severe acute mammary gland infection with necrotizing mastitis and high fever was observed for both H5N1 genotypes/strains. Milk production was rapidly and drastically reduced and the physical condition of the cows was severely compromised. Virus titers in milk rapidly peaked at 108 TCID50/mL, but systemic infection did not ensue. Notably, adaptive mutation PB2 E627K emerged after intramammary replication of H5N1 euDG. Our data suggest that in addition to H5N1 B3.13, other HPAIV H5N1 strains have the potential to replicate in the udder of cows and that milk and milking procedures, rather than respiratory spread, are likely the primary routes of H5N1 transmission between cattle.

microbiology↗

bioRxiv2023

Single-cycle SARS-CoV-2 vaccine elicits high protection and sterilizing immunity in hamsters

Vaccines have been central in ending the COVID-19 pandemic, but newly emerging SARS-CoV-2 variants increasingly escape first-generation vaccine protection. To fill this gap, live particle-based vaccines mimicking natural infection aim at protecting against a broader spectrum of virus variants. We designed "single-cycle SARS-CoV-2 viruses" (SCVs) that lack essential viral genes, possess superior immune-modulatory features and provide an excellent safety profile in the Syrian hamster model. Full protection of all intranasally vaccinated animals was achieved against an autologous challenge with SARS-CoV-2 virus using an Envelope-gene-deleted vaccine candidate. By deleting key immune-downregulating genes, sterilizing immunity was achieved with an advanced candidate without virus spread to contact animals. Hence, SCVs have the potential to induce a broad and durable protection against COVID-19 superior to a natural infection.

molecular biology↗

bioRxiv2023

Assessment of Immunogenicity and Efficacy of CV0501 mRNA-based Omicron COVID-19 Vaccination in Small Animal Models

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) Omicron and its subvariants (BA.2, BA.4, BA.5) represent the most commonly circulating variants of concern (VOC) in the coronavirus disease 2019 (COVID-19) pandemic in 2022. Despite high vaccination rates with approved SARS-CoV-2 vaccines encoding the ancestral spike (S) protein, these Omicron subvariants have collectively resulted in increased viral transmission and disease incidence. This necessitates the development and characterization of vaccines incorporating later emerging S proteins to enhance protection against VOC. In this context, bivalent vaccine formulations may induce broad protection against VOC and potential future SARS-CoV-2 variants. Here, we report preclinical data for a lipid nanoparticle (LNP)-formulated RNActive(R) N1-methylpseudouridine (N1m{Psi}) modified mRNA vaccine (CV0501) based on our second-generation SARS-CoV-2 vaccine CV2CoV, encoding the S protein of Omicron BA.1. The immunogenicity of CV0501, alone or in combination with a corresponding vaccine encoding the ancestral S protein (ancestral N1m{Psi}), was first measured in dose-response and booster immunization studies performed in Wistar rats. Both monovalent CV0501 and bivalent CV0501/ancestral N1m{Psi} immunization induced robust neutralizing antibody titers against the BA.1, BA.2 and BA.5 Omicron subvariants, in addition to other SARS-CoV-2 variants in a booster immunization study. The protective efficacy of monovalent CV0501 against live SARS-CoV-2 BA.2 infection was then assessed in hamsters. Monovalent CV0501 significantly reduced SARS-CoV-2 BA.2 viral loads in the airways, demonstrating protection induced by CV0501 vaccination. CV0501 has now advanced into human Phase 1 clinical trials (ClinicalTrials.gov Identifier: NCT05477186).

immunology↗

bioRxiv2022

Serological screening in wild ruminants in Germany, 2021/22: No evidence of SARS-CoV-2, bluetongue virus or pestivirus spread but high seroprevalences against Schmallenberg virus

Wildlife animals may be susceptible for multiple infectious agents of public health or veterinary relevance, thereby potentially forming a reservoir that bears the constant risk of re-introduction into the human or livestock population. Here, we serologically investigated 493 wild ruminant samples collected in the 2021/22 hunting season in Germany for the presence of antibodies against the severe acute respiratory coronavirus 2 (SARS-CoV-2) and four viruses pathogenic for domestic ruminants, namely the orthobunyavirus Schmallenberg virus (SBV), the reovirus bluetongue virus (BTV) and ruminant pestiviruses like bovine viral diarrhoea virus or border disease virus. The animal species comprised fallow deer, red deer, roe deer, mouflon and wisent. For coronavirus serology, additional 307 fallow, roe and red deer samples collected between 2017 and 2020 at three military training areas were included. While antibodies against SBV could be detected in about 13.6% of the samples collected in 2021/22, only one fallow deer of unknown age tested positive for anti-BTV antibodies and all samples reacted negative for antibodies against ruminant pestiviruses. In an ELISA based on the receptor-binding domain (RBD) of SARS-CoV-2, 25 out of 493 (5.1%) samples collected in autumn and winter 2021/22 scored positive. This sero-reactivity could not be confirmed by the highly specific virus neutralization test, occurred also in 2017, 2018 and 2019, i.e. prior to the human SARS-CoV-2 pandemic, and was likewise observed against the RBD of the related SARS-CoV-1. Therefore, the SARS-CoV-2-seroreactivity was most likely induced by another, hitherto unknown deer virus belonging to the subgenus Sarbecovirus of betacoronaviruses.

microbiology↗

bioRxiv2021

Genomic characterization of world's longest selection experiment in mouse reveals the complexity of polygenic traits.

A unique set of mouse outbred lines has been generated through selective breeding in the longest selection experiment ever conducted on mice. Over the course of >140 generations, selection on the control line has given rise to two extremely fertile lines (>20 pups per litter each), two giant growth lines (one lean, one obese) and one long-distance running line. Genomic analysis revealed line-specific patterns of genetic variation among lines and high levels of homozygosity within lines as a result of long-term intensive selection, genetic drift and isolation. Detection of line-specific patterns of genetic differentiation and structural variation revealed multiple candidate genes behind the improvement of the selected traits. We conclude that the genomes of these lines are rich in beneficial alleles for the respective selected traits and represent an invaluable resource for unraveling the polygenic basis of fertility, obesity, muscle growth and endurance fitness.

genomics↗

bioRxiv2021

CV2CoV, an enhanced mRNA-based SARS-CoV-2 vaccine candidate, supports higher protein expression and improved immunogenicity in rats

More than two years after the emergence of SARS-CoV-2, 33 COVID-19 vaccines, based on different platforms, have been approved in 197 countries. Novel variants that are less efficiently neutralised by antibodies raised against ancestral SARS-CoV-2 are circulating, highlighting the need to adapt vaccination strategies. Here, we compare the immunogenicity of a first-generation mRNA vaccine candidate, CVnCoV, with a second-generation mRNA vaccine candidate, CV2CoV, in rats. Higher levels of spike (S) protein expression were observed in cell culture with CV2CoV mRNA than with CVnCoV mRNA. Vaccination with CV2CoV also induced higher titres of virus neutralising antibodies with accelerated kinetics in rats compared with CVnCoV. Significant cross-neutralization of the SARS-CoV-2 variants, Alpha (B.1.1.7), Beta (B.1.351), and the mink variant (B1.1.298) that were circulating at the time in early 2021 was also demonstrated. In addition, CV2CoV induced higher levels of antibodies at lower doses than CVnCoV, suggesting that dose-sparing could be possible with the next generation SARS-CoV-2 vaccine which could improve worldwide vaccine supply.

immunology↗

bioRxiv2021

CVnCoV protects human ACE2 transgenic mice from ancestral B BavPat1 and emerging B.1.351 SARS-CoV-2

The ongoing severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) pandemic necessitates the fast development of vaccines as the primary control option. Recently, viral mutants termed "variants of concern" (VOC) have emerged with the potential to escape host immunity. VOC B.1.351 was first discovered in South Africa in late 2020, and causes global concern due to poor neutralization with propensity to evade preexisting immunity from ancestral strains. We tested the efficacy of a spike encoding mRNA vaccine (CVnCoV) against the ancestral strain BavPat1 and the novel VOC B.1.351 in a K18-hACE2 transgenic mouse model. Naive mice and mice immunized with formalin-inactivated SARS-CoV-2 preparation were used as controls. mRNA-immunized mice developed elevated SARS-CoV-2 RBD-specific antibody as well as neutralization titers against the ancestral strain BavPat1. Neutralization titers against VOC B.1.351 were readily detectable but significantly reduced compared to BavPat1. VOC B.1.351-infected control animals experienced a delayed course of disease, yet nearly all SARS-CoV-2 challenged naive mice succumbed with virus dissemination and high viral loads. CVnCoV vaccine completely protected the animals from disease and mortality caused by either viral strain. Moreover, SARS-CoV-2 was not detected in oral swabs, lung, or brain in these groups. Only partial protection was observed in mice receiving the formalin-inactivated virus preparation. Despite lower neutralizing antibody titers compared to the ancestral strain BavPat1, CVnCoV shows complete disease protection against the novel VOC B.1.351 in our studies.

microbiology↗

bioRxiv2020

Multi-species ELISA for the detection of antibodies against SARS-CoV-2 in animals

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused a pandemic with millions of infected humans and hundreds of thousands of fatalities. As the novel disease - referred to as COVID-19 - unfolded, occasional anthropozoonotic infections of animals by owners or caretakers were reported in dogs, felid species and farmed mink. Further species were shown to be susceptible under experimental conditions. The extent of natural infections of animals, however, is still largely unknown. Serological methods will be useful tools for tracing SARS-CoV-2 infections in animals once test systems are validated for use in different species. Here, we developed an indirect multi-species ELISA based on the receptor-binding domain (RBD) of SARS-CoV-2. The newly established ELISA was validated using 59 sera of infected or vaccinated animals including ferrets, raccoon dogs, hamsters, rabbits, chickens, cattle and a cat, and a total of 220 antibody-negative sera of the same animal species. Overall, a diagnostic specificity of 100.0% and sensitivity of 98.31% was achieved, and the functionality with every species included in this study could be demonstrated. Hence, a versatile and reliable ELISA protocol was established that enables high-throughput antibody detection in a broad range of animal species, which may be used for outbreak investigations, to assess the seroprevalence in susceptible species or to screen for reservoir or intermediate hosts.

microbiology↗