Biology subjects

Frese, M.

Publications and source records attributed to Frese, 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

A human RNA ligase that operates via auto- and RNA-AMPylation

Different forms of life are known to express RNA ligases that catalyse the condensation of a 3-hydroxy group and a 5-terminal phosphate of RNA. No such RNA ligases have yet been identified in vertebrates. Here, we report that the hitherto uncharacterised human protein chromosome 12 open reading frame 29 (C12orf29), which we identified by a chemical proteomics approach, is a 5-3 RNA ligase. C12orf29 catalyses RNA ligation via auto-AMPylation of a critical lysine residue by using ATP as a cosubstrate and subsequent AMP transfer to the 5-phosphate of an RNA substrate followed by phosphodiester bond formation. Studies at the cellular level reveal the involvement of C12orf29 in maintaining RNA integrity upon cellular stress induced by reactive oxygen species. These findings highlight the importance of RNA ligation for cellular fitness.

biochemistry↗

bioRxiv2022

Hepatobiliary organoids derived from leporids support the replication of hepatotropic lagoviruses

Lagoviruses, family Caliciviridae, are some of the most virulent vertebrate viruses known. They infect leporids, i.e., rabbits (Oryctolagus spp.), hares (Lepus spp.) and cottontails (Sylvilagus spp.) and rapidly kill over 95% of susceptible animals. Pathogenic lagoviruses are hepatotropic and induce a fulminant hepatitis that typically leads to disseminated intravascular coagulation within 24-72 hours of infection. However, the pathophysiological mechanisms governing this extreme phenotype and other aspects of the fundamental biology of these viruses are poorly understood due to a lack of cell culture systems. Here, we report on a robust and reliable ex vivo model for the cultivation of hepatotropic lagoviruses. We show that three rabbit haemorrhagic disease virus (RHDV) variants, RHDV1, RHDV2 and RHDVa-K5, replicate in monolayer cultures derived from rabbit hepatobiliary organoids. Viral replication was demonstrated by a (i) increase in viral RNA levels of greater than one log10 over a 23-hour period, (ii) detection of viral structural and non-structural proteins, and (iii) detection of double-stranded RNA viral replication intermediates. Furthermore, we generated hepatobiliary organoids from a feral cat (Felis domesticus), a wild mouse (Mus musculus) and a European brown hare (Lepus europaeus) and showed that monolayer cultures derived from the cat and mouse organoids were not permissive for lagovirus infection, while those derived from the hare organoids only supported replication of RHDV2, recapitulating the species tropism that has been observed with these viruses. Our organoid culture system will facilitate future studies into the molecular biology of lagoviruses, which will have considerable import for the conservation of endangered leporid species in Europe and North America and the biocontrol of overabundant rabbit populations in Australia and New Zealand.

microbiology↗

bioRxiv2020

Isolation, culture and maintenance of rabbit intestinal organoids, and organoid-derived cell monolayers

Organoids emulate many aspects of their parental tissue and have been used to study pathogen-host interactions, tissue development and regeneration, metabolic diseases, and other complex biological processes. Here, we report a robust protocol for the isolation, maintenance and differentiation of rabbit small intestinal organoids and organoid-derived cell monolayers. We also report conditions that sustain an intestinal stem cell population in spheroid culture. Rabbit intestinal spheroids and monolayer cultures propagated and expanded most efficiently in L-WRN-conditioned medium that contained the signalling factors Wnt, R-spondin and Noggin, and that had been supplemented with ROCK and TGF-{beta} inhibitors. Organoid and monolayer differentiation was initiated by switching to a medium that contained less of the L-WRN-conditioned medium and was supplemented with ROCK and Notch signalling inhibitors. Using immunofluorescence staining and RT-qPCR, we demonstrate that organoids contained enterocytes, enteroendocrine cells, goblet cells and Paneth cells. These findings demonstrate that our rabbit intestinal organoids have many of the multi-cellular characteristics of, and closely resemble, an intestinal epithelium. This newly established organoid culture system will provide a useful tool to study rabbit gastrointestinal physiology and disease. For example, organoids and organoid-derived cells may be used to propagate and study caliciviruses and other enterotropic pathogens that cannot be grown in conventional cell culture systems.

cell biology↗