Biology subjects

Jenckel, M.

Publications and source records attributed to Jenckel, M..

4 recordsLinked to original sources

bioRxiv2025

Inhibition of interferon signalling improves rabbit calicivirus replication in biliary organoid cultures

The Rabbit haemorrhagic disease virus (RHDV) was discovered 40 years ago. This highly pathogenic virus threatens the integrity of ecosystems in the European rabbits native range, while in Australia, it is used as a biocontrol tool to manage overabundant populations of feral rabbits (Oryctolagus cuniculus). Little is known about the life cycle of this virus due to the absence of a reliable cell culture system. In 2023, we developed a rabbit liver-derived organoid cell culture system that supports RHDV replication but is unable to sustain serial passaging in culture. Here, we report that the interferon signalling pathway inhibitor Ruxolitinib increases virus replication in organoid-derived monolayer cells and, for the first time, enables the serial passaging of RHDV in cell culture. Four consecutive passages were achieved with viral titres reaching the concentration of the initial virus stock as measured by RT-qPCR. Immunofluorescence analysis showed that more cells are infected in the presence of Ruxolitinib. Furthermore, we noted that cells grew faster and formed healthier monolayers in the presence of the interferon inhibitor. To determine the cellular composition of the monolayers, we used single-cell RNA-sequencing, revealing that our organoids consist largely of RHDV-permissive cholangiocytes. IMPORTANCEIn this work, we describe the use of interferon inhibitor to enhance the permissiveness of our recently developed rabbit liver-derived organoid cell culture to RHDV infection. Interferon inhibitors offer a simple and cost-effective approach to increase the replication of difficult-to-grow viruses in culture systems that are not interferon-deficient.

microbiology↗

bioRxiv2022

Pathogen profiling of Australian rabbits by metatranscriptomic sequencing

Australia is known for its long history of using biocontrol agents, like myxoma virus and rabbit haemorrhagic disease virus (RHDV), to manage wild European rabbit populations. Interestingly, while undertaking RHDV surveillance of rabbits that were found dead we observed that approximately 40% of samples were negative for RHDV. To investigate whether other infectious agents are responsible for killing rabbits in Australia we subjected a subset of these RHDV-negative liver samples to metatranscriptomic sequencing. In addition, we investigated whether the host transcriptome data could provide additional differentiation between likely infectious versus non-infectious causes of death. We identified transcripts from several Clostridia species, Pasteurella multocida, Pseudomonas, and Eimeria stiedae in liver samples of several rabbits that had died suddenly, all of which are known to infect rabbits and are capable of causing fulminant disease. In addition, we identified Hepatitis E virus and Cyniclomyces yeast in some samples, both of which are not usually associated with severe disease. In one third of the sequenced liver samples, no infectious agent could be identified. While metatranscriptomic sequencing cannot provide definitive evidence of causation, additional host transcriptome analysis provided further insights to distinguish between pathogenic microbes and commensals or environmental contaminants. Interestingly, three samples where no pathogen could be identified showed evidence of upregulated host immune responses, while immune response pathways were not upregulated when E. stiedae, Pseudomonas, or yeast were detected. In summary, although no new putative rabbit pathogens were identified, this study provides a robust workflow for future investigations into rabbit mortality events. ImportanceWe have observed that approximately 40% of rabbit liver samples submitted for RHDV testing (from rabbits that had died suddenly without obvious cause) are RHDV-negative. Interestingly, a similar finding was reported in pet rabbits in the United Kingdom. This raises the intriguing question of what else is killing rabbits, both in Australia and internationally? Using a metatranscriptomic sequencing approach, we found that Clostridiaceae, Pasteurella multocida, and Eimeria are frequently detected in cases of sudden rabbit death in Australia. While we did not identify any potential new pathogens that could be explored in the context of wild rabbit management, we have validated an approach to explore future mortality events of lagomorphs that may identify candidate novel biocontrols. Furthermore, our findings reaffirm the recommendation to follow good hygiene practices when handling rabbits, since domestic rabbits harboured several pathogens of potential public health significance, including Escherichia, Pasteurella multocida, and Hepatitis E virus.

microbiology↗

bioRxiv2021

Frequent intergenotypic recombination between the non-structural and structural genes is a major driver of epidemiological fitness in caliciviruses

The diversity of lagoviruses (Caliciviridae) in Australia has increased considerably. By the end of 2017, five variants from three viral genotypes were present in populations of Australian rabbits, while prior to 2014 only two variants were known. To understand the interactions between these lagovirus variants we monitored their geographical distribution and relative incidence over time through a landscape-scale competition study, and from this, revealed potential drivers of epidemiological fitness. Within three years of the arrival of GI.1bP-GI.2 (RHDV2) into Australia, we observed the emergence of two novel recombinant lagovirus variants, GI.4eP-GI.2 (4e-recombinant) in New South Wales and GI.4cP-GI.2 (4c-recombinant) in Victoria. Although both novel recombinants contain the non-structural genes from benign, rabbit-specific, enterotropic viruses, these variants were recovered from the livers of both rabbits and hares that had died acutely. This suggests that determinants of host and tissue tropism for lagoviruses are associated with the structural genes, and that tropism is intricately connected with pathogenicity. Phylogenetic analyses demonstrated that the 4c-recombinant emerged independently on multiple occasions, with five distinct lineages observed. Both new recombinant variants replaced the previous dominant parental RHDV2 in their respective geographical areas, despite sharing an identical or near-identical (i.e., single amino acid change) major capsid protein with the parental virus. This suggests that epidemiological fitness of these recombinants was not driven by antigenic variation in the capsid, implicating the non-structural genes as key drivers of epidemiological fitness. Molecular clock estimates place the GI4.e recombination event in early to mid-2015, while the five GI.4c recombination events occurred from late 2015 through to early 2017. The emergence of at least six viable recombinant variants within a two-year period highlights an unprecedented frequency of these events, detectable only due to intensive surveillance, and demonstrates the importance of recombination in lagovirus evolution.

microbiology↗

bioRxiv2020

First description of Hepatitis E virus in Australian rabbits

We report the first detection of Hepatitis E virus in rabbits in Australia. While conducting metatranscriptomic sequencing of liver samples collected from domestic rabbits that had diedwe detected three samples positive for hepatitis E virus. Two viral genome sequences were obtained, which shared 96% nucleotide identity.

zoology↗