Biology subjects

Ulrich, R. G.

Publications and source records attributed to Ulrich, R. G..

10 recordsLinked to original sources

bioRxiv2026

Impact of hepatitis E virus host- and virus-derived insertions on the antiviral response in primary human hepatocytes

Despite the global burden of hepatitis E virus (HEV) infection, host-virus interactions underlying HEV pathogenesis and progression to chronicity remain incompletely understood. This study aimed to characterize the host transcriptomic response to infection with HEV variants harboring different host- and virus-derived insertions in the hypervariable region (HVR), with a focus on innate immune activation. We performed bulk RNA sequencing on PHHs from three donors infected with in vivo-identified HEV-3 variants harboring different HVR insertions (RPS17, HVR duplication, SERPINA1, TRIM22). To compare their replication fitness, we quantified progeny virus titers and viral RNA reads in the cellular transcriptome. Host transcriptomic responses were analyzed in detail at multiple time points to assess virus-induced differential gene expression. To further characterize the response to HEV infection with different HVR insertion variants, we performed gene ontology analysis and identified individual HEV-induced genes. Progeny virus titers at 72 hours post infection (h p.i.) were comparable across all PHH donors and HVR insertion variants. Two donors mounted robust host responses to HEV infection, characterized by widespread gene deregulation and interferon stimulated gene (ISG) upregulation at 72 h p.i. The HVR duplication insertion variant consistently triggered a weaker host response compared to RPS17, SERPINA1 and TRIM22 variants, with significantly fewer differentially expressed genes and reduced ISG induction. Gene ontology term analysis revealed enrichment of antiviral pathways upon infection with the different insertion variants, which was less pronounced for the HVR duplication variant. These findings reveal that HEV HVR rearrangement variants elicit distinct host response patterns. Importantly, our results suggest a positive correlation of viral replication and host response induction. This indicates that the HVR may play a crucial role in shaping host-virus interactions.

molecular biology↗

bioRxiv2025

Cell surface localization and intercellular transfer of the hantavirus nucleocapsid protein via a viral assembly-independent mechanism

Hantaviruses are segmented negative-sense RNA viruses that package their genome into helical ribonucleocapsids, by oligomerization of the nucleocapsid (N) protein along the viral RNA. Upon transmission to humans, hantaviruses can cause severe disease characterized by increased vascular permeability in the microvasculature, a key driver of pathogenesis. In patients and rodent reservoirs, robust and persistent antibody responses against the nucleocapsid (N) protein are consistently observed. Here we investigated whether the hantavirus N protein, described as a strictly intracellular protein, is released into the extracellular environment during viral infection. By using diverse experimental approaches, we demonstrate that in cells infected with Andes virus (ANDV) or the non-pathogenic Tula virus (TULV), the N protein localizes on the plasma membrane. Transfection experiments further revealed that the surface localization of N proteins from Murine, Arvicoline, Neotomine and Sigmodontine rodent-reservoir-associated hantaviruses did not require co-expression of other viral proteins indicating that its trafficking to the cell surface is mediated by a mechanism distinct from canonical virion assembly pathways. Moreover, we show that the N protein is secreted from cells into the extracellular milieu and is further transferred to neighboring cells. Interestingly, despite being present on the cell surface and secreted into the extracellular media, the TULV N protein transfer of the N protein to neighboring cells was significantly lower compared to that of ANDV N protein. The extracellular presence of hantavirus N proteins, and likely also from other clinically-relevant bunyaviruses, unveils new possible functions of the protein during the viral infection cycle, which is likely related to immune responses, immune modulation and viral pathogenesis.

microbiology↗

bioRxiv2025

Maternal antibody-mediated elimination of a Puumala hantavirus outbreak in a bank vole colony

Bank voles (Myodes glareolus syn. Clethrionomys glareolus) are frequently used as an animal model in ecological and biomedical studies, and are important reservoir of viral and bacterial zoonotic pathogens, e.g. of Puumala hantavirus (PUUV). Here we describe an accidental PUUV outbreak in a large bank vole laboratory colony by incursion of infected wild-trapped bank voles, and a successful eradication of the virus. The eradication plan was based on results of previous studies, which showed that maternal antibodies (MatAb) protect the young from infection for up to 40 days after the weaning, four weeks longer than the estimated duration of maintaining infectivity of PUUV in the environment. After ensuring that most animals are infected, 620 pairs were mated on the same day. Only females that showed PUUV-specific antibodies and gave offspring within 26 days after the mating were retained. All individuals of the parental generation were euthanized before the last weaning. The weaned offspring was moved to individually ventilated cages (IVC) and repeatedly tested for the presence of PUUV-specific antibodies and RNA. A few infected and suspicious animals were euthanised. Then the animals were mated (in IVC) and after producing grand-offspring euthanised and tested for PUUV RNA in lungs. No PUUV RNA was detected, and no animals showed PUUV-specific antibodies in next generations. The successful clearance confirmed the protective efficiency of PUUV-specific MatAb. The procedure for clearance of PUUV in the bank vole colony may represent a blueprint for similar approaches in precious colonies of other rodents infected by similar pathogens. Author SummaryIn 2006 we started a unique long-term experiment on the bank vole, a common European rodent. Our goal was to study how animals can adapt to different challenges - a process called adaptive radiation. We established 16 vole lines: four control lines and others selected for specific behavioural and physiological traits. Over the years, this colony became an important model for studying evolution, physiology, and behaviour. Unfortunately, the colony became infected with Puumala hantavirus. The virus is mild for voles but can cause serious zoonotic illness in humans, without specific medical treatment available. At first, it seemed that the entire colony would have to be destroyed - a loss of thousands of animals and many years of research. However, we used a natural advantage: young voles born to infected mothers are temporarily protected by maternal antibodies. By carefully planning breeding, isolation, and testing, we created conditions where the virus lost its strength before the young lost their protection. This simple yet challenging approach worked - we saved the colony. Because many animals respond to viruses in a similar way, our method can help rescue other valuable research populations without complex procedures like embryo transfer or cross-fostering.

zoology↗

bioRxiv2025

A global serosurvey of RNA virus-reactive antibodies in bats and rodents reveals the enzootic presence of flavi- and paramyxoviruses in African Pteropodidae

Bats and rodents have been identified as reservoir hosts of diverse RNA viruses that pose potential risks to humans. However, overall virus prevalence in wildlife and underlying factors determining the zoonotic potential of reservoir-borne viruses remain poorly characterized. Virus detection often relies on the identification of viral nucleotide sequences and may therefore be limited by variable virus concentration, tissue tropism, sample quality, and duration of infection. In this study, we applied a multiplex immunofluorescence assay to examine bat and rodent seroprevalence against 14 different human pathogenic RNA viruses spanning seven virus families (Coronaviridae, Flaviviridae, Hantaviridae, Paramyxoviridae, Phenuiviridae, Pneumoviridae, Togaviridae). We retrospectively analyzed 1,135 bat (16 species) and 454 rodent (15 species) blood or transudate specimens collected at 63 sites in seven countries. Tropical bats exhibited notably high rates of seropositivity against certain virus families (Flaviviridae: 42.8%; Paramyxoviridae: 60.4%; Togaviridae: 7.5%). Multivariable logistic regression models were created to evaluate the association of tropical bat characteristics with seropositivity. Preliminary findings indicate that large colony size, found among species such as Eidolon helvum and Rousettus aegyptiacus, is a risk factor for orthoflavi- and orthorubulavirus infection, consistent with the communal spread of bat-adapted viruses. Author SummaryMany animal populations carry viruses that have the potential to spill over to humans and cause severe disease. Despite surveillance efforts, it is logistically challenging to detect virus infections in wildlife, as viruses may have a short duration of infection or unknown routes of transmission. In this study, we examined blood and transudate samples from rodents and bats around the world for antibodies against 14 different viruses known to cause disease in humans. We analyzed the samples via a mosaic chip-based immunofluorescence test, which has the advantage of detecting antibodies against whole-virus antigen. This method allows for broad surveillance, as we would also expect to uncover evidence of past infection with bat- and rodent-adapted viruses that are related, but not identical, to known human pathogens. We detected antibodies against all seven virus families we examined, with especially high detection rates of antibodies in tropical bats. We used the results to construct multivariable logistic regression models of tropical bat seroprevalence to examine potential associations between tropical bat characteristics and previous infection by certain virus families. Bats with large colony sizes, such as Eidolon helvum and Rousettus aegyptiacus, were apparently at increased risk of infection with orthoflavi- and orthorubulaviruses compared to other tropical bat species.

microbiology↗

bioRxiv2025

A century-old museum sample reveals abandavirus with modern day presence in northernEuropean bats

Ancient genome sequences provide invaluable insights into the origin and evolution of viral pathogens, offering a broader temporal perspective that extends well beyond the limited timespan of clinical data, which typically covers at most a few decades. Whereas ancient viral DNA is relatively frequently recovered, ancient viral RNA genomes are scarce due to the fragile nature of RNA molecules. In this study, we explored the feasibility of detecting ancient viral RNA in ethanol-preserved bat samples from a museum collection. We not only detected viral genome fragments but also recovered the coding-complete genome of a bandavirus (species Bandavirus zwieselense, family Phenuiviridae, order Hareavirales, class Bunyaviricetes) from a Common pipistrelle (Pipistrellus pipistrellus) bat collected in northern Germany in 1919. To investigate the modern distribution of Bandavirus zwieselense, we screened bat organs collected in Germany and the Netherlands via RT-qPCR, identifying modern counterparts in nine Common Pipistrelle (P. pipistrellus) bats (collected between 2010 and 2018), and one Serotine bat (Eptesicus serotinus, collected in 1999). The resulting genomic data enabled us to map phylogenetic relationships within this previously uncharacterized virus species (Bandavirus zwieselense) and estimate the timeframe for the most recent common ancestor. Additionally, we performed functional analysis of the S segment encoded nonstructural (NSs) protein of Bandavirus zwieselense in human HEK-293T cells, demonstrating its ability to block interferon induction, a characteristic also observed in the related human-pathogenic Severe fever with thrombocytopenia syndrome virus (SFTSV, species Bandavirus dabieense). This study demonstrates the feasibility of recovering and characterizing viral genomes from ethanol-preserved ancient RNA material, underscoring the significant potential of museum collections to contribute to the understanding of RNA virus evolution.

microbiology↗

bioRxiv2024

On the ecology of Acinetobacter baumannii - jet stream rider and opportunist by nature

The natural reservoirs of the nosocomial pathogen Acinetobacter baumannii are not well defined. We previously identified white storks as a model system to study the ecology of A. baumannii. Having screened more than 1,300 white stork nestlings over a period of six years across different regions of Poland and Germany (overall isolation rate of [~]29.5%), including food chain analyses and environmental samplings, we come up with a detailed picture of the dynamics and diversity of A. baumannii in their natural habitats. Adult storks, rather than being stably colonized with strains of A. baumannii which are successively transferred to their offspring, instead initially encounter these bacteria while foraging. Among their common food sources, consisting of earthworms, small mammals, and insects, we identified earthworms as a potential source of A. baumannii, but more so the associated soil as well as plant roots. Through this, hotspot soil and compost habitats were identified which enable population dynamics to be studied over the course of the year. We demonstrate that sterilized plant material is rapidly colonized by airborne A. baumannii suggesting they patrol to search for novel habitats, being opportunist by nature. The prevalence of A. baumannii exhibited a strong seasonality and peaked during summer. The strains we collected in Poland and Germany represent more than 50% of the worldwide known diversity in terms of the intrinsic OXA-51-like {beta}-lactamase. A set of [~]400 genomes was determined and compared to a diverse set of publicly available genomes. Our pan-genome estimate of the species ([~]51,000 unique genes) more than doubles the amount proposed by previous studies. Core-genome based phylogenetic analyses illustrated numerous links between wildlife isolates and hospital strains, including ancient as well as recent intercontinental transfer. Our data further suggest massive radiation within the species early after its emergence, matching with human activity during the Neolithic. Deforestation in particular seemed to set the stage for this bloom as we found that forests do not provide conducive conditions for the proliferation of A. baumannii. In contrast, wet and nutrient-rich soil alongside rivers sampled during the summer can yield an isolation rate of [~]30%. Linking published work on the interaction between A. baumannii and fungi and on aspergillosis as a major cause of mortality in white stork nestlings to our findings, we hypothesized that fungi and A. baumannii share a long history of coevolution. Interaction studies revealed the capability of A. baumannii to adhere to fungal spores and to suppress spore germination. Taken together, the intrinsic resistance endowment and potential to acquire antibiotic resistance can be explained by coevolution with antibiotic-producing fungi and other microorganisms within soil, and resistance to desiccation stress and radiation can be interpreted in the light of intercontinental hitchhiking through fungal spores. Originality - SignificanceThe ecology of the nosocomial pathogen Acinetobacter baumannii remains poorly understood outside the hospital. Here, we present the most comprehensive study on its environmental biology to date, after having collected more than 1,450 independent isolates of which around 400 were whole genome-sequenced. This study more than doubles the size of the pan-genome of the species, illustrating both the diversity of our collection and the bias of previous work, but also the bottleneck for the establishment of lineages within the hospital environment. We reached isolation rates of about 30% both in white stork (Ciconia ciconia) nestlings and in soil samples when considering for sampling all preferences of A. baumannii we uncovered. Thus, it is now possible to study the ecology and evolution of A. baumannii in nature at an unprecedented temporal and spatial resolution. We describe the worldwide spread of A. baumannii lineages in nature as an ancient phenomenon that even surpasses that of human-associated bacteria in magnitude. This is likely due to airborne spread, putatively facilitated by association with fungal spores. We propose that A. baumannii is an opportunist by nature, using airborne patrolling to rapidly enter new suitable habitats consisting of organic matter in early stages of decomposition. Our collective data suggest that A. baumannii, early after its speciation, went through massive radiation during the Neolithic, likely due to deforestation, settlement and farming producing numerous favorable habitats. Their natural lifestyle, which requires rapid adaptability to various habitats as well as tolerance to desiccation, radiation and antibiotic stress, perfectly predispose these opportunistic pathogens to establish within the hospital setting. Comparison of genomes from environmental and clinical isolates will now enable studies of the adaptive evolution of environmental bacteria towards multidrug-resistant opportunistic pathogens.

microbiology↗

bioRxiv2023

SARS-CoV-2 and other coronaviruses in rats, Berlin, Germany, 2023

We tested 130 rats trapped in Berlin for coronaviruses. Antibodies against SARS-CoV-2 were detected in a single animal only, but not in further 66 rats from the same location, speaking against virus circulation in the rat population. All animals tested negative for SARS-CoV-2 by RT-PCR. However, rodent-associated alphacoronaviruses were found.

microbiology↗

bioRxiv2023

Small in size but huge as reservoir -- insights into the virome of European white-toothed shrews

While the virome and immune system of bats and rodents have been extensively studied, comprehensive data are lacking for insectivores. Anthropogenic land use and outdoor recreational activities may lead to an expansion of the human-shrew interface with the risk of zoonotic infections, as reported for Borna disease virus 1. We investigated the virosphere of four white-toothed shrew species from Central Europe, addressing the One Health concept of spillover prevention. A high diversity of viruses was identified, including several co-infections. Whole genomes were generated for novel species of paramyxoviruses (n=3), nairoviruses (n=2) and hepevirus. Phylogenetically, they are closely related to WHO priority diseases, such as henipaviruses. High viral loads of orthoparamyxoviruses were detected in kidneys, in well-perfused organs for orthonairoviruses, and an association with liver and intestine was identified for orthohepevirus. Our study highlights the virus diversity present in shrews, not only in biodiversity hotspots but also in industrialised countries.

evolutionary biology↗

bioRxiv2022

Mystery of fatal "Staggering disease" unravelled: Novel rustrela virus causes severe encephalomyelitis in domestic cats

Staggering disease is a neurological disorder considered a threat to European domestic cats (Felis catus) for almost five decades. However, its aetiology has remained obscure. Rustrela virus (RusV), a relative of rubella virus, has recently been shown to be associated with encephalitis in a broad range of mammalian hosts. Here, we report the detection of RusV RNA and antigen by metagenomic sequencing, RT-qPCR, in-situ hybridization and immunohistochemistry in brain tissues of 28 out of 29 cats with non-suppurative meningoencephalomyelitis and staggering disease-like neurological disorder from Sweden, Austria, and Germany, but not in non-affected control cats. Screening of possible reservoir hosts in Sweden revealed RusV infection in wood mice (Apodemus sylvaticus). Our work strongly indicates RusV as the long-sought cause of feline staggering disease. Given its broad host spectrum and considerable geographic range, RusV may be the aetiological agent of neuropathologies in further mammals, possibly even including humans.

microbiology↗

bioRxiv2020

Peptide recognition and dephosphorylation by the vaccinia VH1 phosphatase

The VH1 protein encoded by the highly conserved H1 locus of orthopoxviruses is a dual-specificity phosphatase (DUSPs) that hydrolyzes phosphate groups from phosphorylated tyrosine, serine, and threonine residues of viral and host cell proteins. Because the DUSP activities are required for virus replication, VH1 is a prime target for the development of therapeutic inhibitors. However, the presentation of a shallow catalytic site has thwarted all drug development efforts. As an alternative to direct targeting of catalytic pockets, we describe surface contacts between VH1 and substrates that are essential for full activity and provide a new pathway for developing inhibitors of protein-protein interactions. Critical amino acid residues were manipulated by site-directed mutagenesis of VH1, and perturbation of peptide substrate interactions based on these mutations were assessed by high-throughput assays that employed surface plasmon resonance and phosphatase activities. Two positively-charged residues (Lys-20 and Lys-22) and the hydrophobic side chain of Met-60 appear to orient the polarity of the pTyr peptide on the VH1 surface, while additional amino acid residues that flank the catalytic site contribute to substrate recognition and productive dephosphorylation. We propose that the enzyme-substrate contact residues described here may serve as molecular targets for the development of inhibitors that specifically block VH1 catalytic activity and thus poxvirus replication.

biochemistry↗