Biology subjects

Wylezich, C.

Publications and source records attributed to Wylezich, C..

10 recordsLinked to original sources

bioRxiv2025

In vivo models for rustrela virus (RusV) infection in potential reservoir and spill-over hosts

Rustrela virus (RusV; species Rubivirus strelense) is a recently discovered relative of the human rubella virus (Rubivirus rubellae) and causes fatal non-suppurative meningoencephalomyelitis in a broad range of mammalian domestic, wild and zoo animals, in Europe and the USA, including staggering disease in domestic cats. Based on its reportedly broad host range, a zoonotic potential of RusV cannot be excluded. Apparently healthy yellow-necked field mice (Apodemus flavicollis) and wood mice (Apodemus sylvaticus) were identified as potential reservoir hosts. In this study, we experimentally inoculated wood mice and Lewis rats with brain homogenates of RusV-infected animals. Intracranial as well as combined intranasal/peroral inoculation resulted in apparently persistent RusV infection in both rodent species, while combined intramuscular/subcutaneous injection failed to establish detectable infection. Viral loads were highest in the central nervous system, but viral RNA was prominently found also in mucosal organs of wood mice. Viral RNA was frequently detected in oral swabs from infected wood mice, but only sparsely from rats. Neither wood mice nor rats presented neurological signs during twelve weeks after infection. However, RusV-infected rats showed significantly reduced body weight. A lymphohistiocytic meningoencephalomyelitis was observed in infected rats, whereas infected wood mice infrequently developed minimal lesions in the brain. Our study provides the first infection model for RusV and indicates that natural infection may occur via mucosal routes. Shedding of viral RNA suggests wood mice to serve as natural reservoir hosts. In rats, we could reproduce a lymphohistiocytic meningoencephalomyelitis, as described for diseased cats and other tentative non-reservoir hosts.

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↗

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↗

bioRxiv2022

The spike gene is a major determinant for the SARS-CoV-2 Omicron-BA.1 phenotype

Variant of concern (VOC) Omicron-BA1 has achieved global predominance in early 2022. Therefore, surveillance and comprehensive characterization of Omicron-BA.1 in advanced primary cell culture systems and multiple animal models is urgently needed. Here, we characterized Omicron-BA.1 and recombinant Omicron-BA.1 spike gene mutants in comparison with VOC Delta in well-differentiated primary human nasal and bronchial epithelial cells in vitro, followed by in vivo fitness characterization in naive hamsters, ferrets and hACE2-expressing mice, and in immunized hACE2-mice. We demonstrate a spike-mediated enhancement of early replication of Omicron-BA.1 in nasal epithelial cultures, but limited replication in bronchial epithelial cultures. In Syrian hamsters, Delta showed dominance over Omicron-BA.1 and in ferrets, Omicron-BA.1 infection was abortive. In mice expressing the authentic hACE2-receptor, Delta and a Delta spike clone also showed dominance over Omicron-BA.1 and an Omicron-BA.1 spike clone, respectively. Interestingly, in naive K18-hACE2 mice, we observed Delta spike-mediated increased replication and pathogenicity and Omicron-BA.1 spike-mediated reduced replication and pathogenicity, suggesting that the spike gene is a major determinant of both Delta and Omicron-BA.1 replication and pathogenicity. Finally, the Omicron-BA.1 spike clone was less well controlled by mRNA-vaccination in K18-hACE2-mice and became more competitive compared to the progenitor and Delta spike clones, suggesting that spike gene-mediated immune evasion is another important factor that led to Omicron-BA.1 dominance.

microbiology↗

bioRxiv2022

Compellingly high SARS-CoV-2 susceptibility of Golden Syrian hamsters suggests multiple zoonotic infections of pet hamsters during the COVID-19 pandemic

Golden Syrian hamsters (Mesocricetus auratus) are used as a research model for severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2). Millions of Golden Syrian hamsters are also kept as pets in close contact to humans. To determine the minimum infective dose (MID) for assessing the zoonotic transmission risk, and to define the optimal infection dose for experimental studies, we orotracheally inoculated hamsters with SARS-CoV-2 doses from 1*105 to 1*10-4 tissue culture infectious dose 50 (TCID50). Body weight and virus shedding were monitored daily. 1*10-3 TCID50 was defined as the MID, and this was still sufficient to induce virus shedding at levels up to 102.75 TCID50/ml, equaling the estimated MID for humans. Virological and histological data revealed 1*102 TCID50 as the optimal dose for experimental infections. This compellingly high susceptibility resulting in productive infections in Golden Syrian hamsters needs to be considered also as a source of SARS-CoV-2 infections in humans.

microbiology↗

bioRxiv2021

Revisiting rustrela virus - new cases of encephalitis and a solution to the capsid enigma

Rustrela virus (RusV, species Rubivirus strelense) is a recently discovered relative of rubella virus (RuV) that has been detected in cases of encephalitis across a wide spectrum of mammals, including placental and marsupial animals. Here we diagnosed two additional cases of fatal RusV-associated meningoencephalitis in a South American coati (Nasua nasua) and a Eurasian otter (Lutra lutra) that were detected in a zoological garden with history of prior RusV infections. Both animals showed abnormal movement or unusual behaviour and their brains tested positive for RusV using specific RT-qPCR and RNA in situ hybridization. As previous sequencing of RusV proved to be very challenging, we employed a sophisticated target-specific capture enrichment with specifically designed RNA baits to generate complete RusV genome sequences from both detected encephalitic animals and apparently healthy wild yellow-necked field mice (Apodemus flavicollis). Furthermore, the technique was used to revise three previously published RusV genomes from two encephalitic animals and a wild yellow-necked field mouse. Virus-to-host sequence ratio and thereby sequence coverage improved markedly using the enrichment method as compared to standard procedures. When comparing the newly generated RusV sequences to the previously published RusV genomes, we identified a previously undetected stretch of 309 nucleotides predicted to represent the intergenic region and the sequence encoding the N-terminus of the capsid protein. This indicated that the original RusV sequence was likely incomplete due to misassembly of the genome at a region with an exceptionally high G+C content of >80 mol%, which could not be resolved even by enormous sequencing efforts with standard methods. The updated capsid protein amino acid sequence now resembles those of RuV and ruhugu virus in size and harbours a predicted RNA binding domain that was not encoded in the original RusV genome version. The new sequence data indicate that RusV has the largest overall genome (9,631 nucleotides), intergenic region (290 nucleotides) and capsid protein-encoding sequence (331 codons) within the genus Rubivirus.

microbiology↗

bioRxiv2021

Enhanced fitness of SARS-CoV-2 variant of concern B.1.1.7, but not B.1.351, in animal models

Emerging variants of concern (VOCs) drive the SARS-CoV-2 pandemic. We assessed VOC B.1.1.7, now prevalent in several countries, and VOC B.1.351, representing the greatest threat to populations with immunity to the early SARS-CoV-2 progenitors. B.1.1.7 showed a clear fitness advantage over the progenitor variant (wt-S614G) in ferrets and two mouse models, where the substitutions in the spike glycoprotein were major drivers for fitness advantage. In the "superspreader" hamster model, B.1.1.7 and wt-S614G had comparable fitness, whereas B.1.351 was outcompeted. The VOCs had similar replication kinetics as compared to wt-S614G in human airway epithelial cultures. Our study highlights the importance of using multiple models for complete fitness characterization of VOCs and demonstrates adaptation of B.1.1.7 towards increased upper respiratory tract replication and enhanced transmission in vivo. Summary sentenceB.1.1.7 VOC outcompetes progenitor SARS-CoV-2 in upper respiratory tract replication competition in vivo.

microbiology↗

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

Susceptibility of raccoon dogs for experimental SARS-CoV-2 infection

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerged in China at the end of 2019, and became pandemic. The zoonotic virus most likely originated from bats, but definite intermediate hosts have not yet been identified. Raccoon dogs (Nyctereutes procyonoides) are kept for fur production, in particular in China, and were suspected as potential intermediate host for both SARS-CoV6 and SARS-CoV2. Here we demonstrate susceptibility of raccoon dogs for SARS-CoV-2 infection after intranasal inoculation and transmission to direct contact animals. Rapid, high level virus shedding, in combination with minor clinical signs and pathohistological changes, seroconversion and absence of viral adaptation highlight the role of raccoon dogs as a potential intermediate host. The results are highly relevant for control strategies and emphasize the risk that raccoon dogs may represent a potential SARS-CoV-2 reservoir. Our results support the establishment of adequate surveillance and risk mitigation strategies for kept and wild raccoon dogs. Article Summary LineRaccoon dogs are susceptible to and efficiently transmit SARS-CoV2 and may serve as intermediate host

microbiology↗

bioRxiv2020

Next-generation diagnostics: virus capture facilitates a sensitive viral diagnosis for epizootic and zoonotic pathogens including SARS-CoV-2

BackgroundThe detection of pathogens in clinical and environmental samples using high-throughput sequencing (HTS) is often hampered by large amounts of background information, which is especially true for viruses with small genomes. Enormous sequencing depth can be necessary to compile sufficient information for identification of a certain pathogen. Generic HTS combining with in-solution capture enrichment can markedly increase the sensitivity for virus detection in complex diagnostic samples. MethodsA virus panel based on the principle of biotinylated RNA-baits was developed for specific capture enrichment of epizootic and zoonotic viruses (VirBaits). The VirBaits set was supplemented by a SARS-CoV-2 predesigned bait set for testing recent SARS-CoV-2 positive samples. Libraries generated from complex samples were sequenced via generic HTS and afterwards enriched with the VirBaits set. For validation, an internal proficiency test for emerging epizootic and zoonotic viruses (African swine fever virus, Ebolavirus, Marburgvirus, Nipah henipavirus, Rift Valley fever virus) was conducted. ResultsThe VirBaits set consists of 177,471 RNA-baits (80-mer) based on about 18,800 complete viral genomes targeting 35 epizootic and zoonotic viruses. In all tested samples, viruses with both DNA and RNA genomes were clearly enriched ranging from about 10-fold to 10,000-fold for viruses including distantly related viruses with at least 72% overall identity to viruses represented in the bait set. Viruses showing a lower overall identity (38% and 46%) to them were not enriched but could nonetheless be detected based on capturing conserved genome regions. The internal proficiency test supports the improved virus detection using the combination of HTS plus targeted enrichment but also point to the risk of carryover between samples. ConclusionsThe VirBaits approach showed a high diagnostic performance, also for distantly related viruses. The bait set is modular and expandable according to the favored diagnostics, health sector or research question. The risk of carryover needs to be taken into consideration. The application of the RNA-baits principle turned out to be user-friendly, and even non-experts (without sophisticated bioinformatics skills) can easily use the VirBait workflow. The rapid extension of the established VirBaits set adapted to actual outbreak events is possible without any problems as shown for SARS-CoV-2.

genomics↗