Biology subjects

Chapuis, A.

Publications and source records attributed to Chapuis, A..

3 recordsLinked to original sources

bioRxiv2025

Transcriptomic study of WSSV infection in Litopenaeus vannamei lymphoid organ via single nuclei RNA sequencing

BackgroundAquaculture is the fastest growing farmed food sector and is a key part of global food security. Crustacean aquaculture, while being one of the most profitable sectors, is threatened by pathogenic diseases such as white spot disease (WSD), which results in severe stock losses and threatens animal health and welfare. In this study, we used novel techniques to study the impact of white spot syndrome virus (WSSV), the causative agent of WSD, on Pacific whiteleg shrimp (Litopenaeus vannamei), and uncover additional information that may be used in creating WSSV-resistant shrimp stocks. ResultsWe successfully developed a novel nuclei isolation protocol optimized for shrimp tissues to prepare our samples for single nuclei RNA-sequencing following a pathogen challenge comprising of 32 adult whiteleg shrimp infected with WSSV either through their feed or by injection. We constructed the first penaeid shrimp lymphoid organ cell atlas to improve our understanding of the characteristics of this immune organ, constructed the UMAPs and identified marker genes that define distinct cell clusters to reveal the biological functions of different cell types within this organ. ConclusionBy comparing gene expression between the control and WSSV-infected samples we uncovered multiple genes of interest that that have the potential to be used as targets for CRISPR gene editing for WSSV-resistance in Pacific whiteleg shrimp. These genes have the potential to be valuable assets for future gene editing studies in commercially important penaeid shrimp species. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=90 SRC="FIGDIR/small/693182v1_ufig1.gif" ALT="Figure 1"> View larger version (24K): org.highwire.dtl.DTLVardef@1be071org.highwire.dtl.DTLVardef@2c3da6org.highwire.dtl.DTLVardef@835e67org.highwire.dtl.DTLVardef@aacff1_HPS_FORMAT_FIGEXP M_FIG C_FIG

genomics↗

bioRxiv2021

Human gut bifidobacteria inhibit the growth of the opportunistic fungal pathogen Candida albicans

The human gut microbiota protects the host from invading pathogens and the overgrowth of indigenous opportunistic species via mechanisms such as competition for nutrients and by production of antimicrobial compounds. Here, we investigated the antagonist activity of human gut bacteria towards Candida albicans, an opportunistic fungal pathogen that can cause severe infections and mortality in susceptible patients. Co-culture batch incubations of C. albicans in the presence of faecal microbiota from six different healthy individuals revealed varying levels of inhibitory activity against C. albicans. 16S rRNA gene sequence profiling of these faecal co-culture bacterial communities showed that the Bifidobacteriaceae family, and Bifidobacterium adolescentis in particular, were most correlated with antagonistic activity against C. albicans. Follow up mechanistic studies confirmed that culture supernatants of Bifidobacterium species, particularly B. adolescentis, inhibited C. albicans in vitro under both aerobic and anaerobic conditions. Production of the fermentation acids acetate and lactate, together with the concomitant decrease in pH, were strong drivers of the inhibitory activity. Bifidobacteria may therefore represent attractive targets for the development of probiotics and prebiotic interventions tailored to enhance inhibitory activity against C. albicans in vivo.

microbiology↗

bioRxiv2017

The Cryptococcus neoformans Titan cell is an inducible and regulated morphotype underlying pathogenesis

Fungi undergo changes in cell shape in response to environmental stimuli that drive pathogenesis and niche adaptation, such as the yeast-to-hyphal transition of dimorphic fungi in response to changing temperature. The basidiomycete Cryptococcus neoformans undergoes an unusual morphogenetic transition in the host lung from haploid yeast to large, highly polyploid cells termed Titan cells. Titan cells influence fungal interaction with host cells, including through increased drug resistance, altered cell size, and altered Pathogen Associated Molecular Pattern exposure. Despite the important role these cells play in pathogenesis, understanding the environmental stimuli that drive the morphological transition, and the molecular mechanisms underlying their unique biology, has been hampered by the lack of a reproducible in vitro induction system. Here we demonstrate reproducible in vitro Titan cell induction in response to environmental stimuli consistent with the host lung. In vitro Titan cells exhibit all the properties of in vivo generated Titan cells, the current gold standard, including altered capsule, cell wall, size, high mother cell ploidy, and aneuploid progeny. We identify bacterial peptidoglycan as a serum compound associated with shift in cell size and ploidy, and demonstrate the capacity of bronchial lavage fluid and E. coli co-culture to induce Titanisation. Additionally, we demonstrate the capacity of our assay to identify established and previously undescribed regulators of Titanisation in vitro and investigate the Titanisation capacity of clinical isolates and their impact on disease outcome. Together, these findings provide new insight into the environmental stimuli and molecular mechanisms underlying the yeast-to-titan transition and establish an essential in vitro model for the future characterization of this important morphotype.\n\nAuthor SummaryChanges in cell shape underlie fungal pathogenesis by allowing immune evasion and dissemination. Aspergillus and Candida albicans hyphae drive tissue penetration. Histoplasma capsulatum and C. albicans yeast growth allows evasion and dissemination. As major virulence determinates, morphogenic transitions are extensively studied in animal models and in vitro. The pathogenic fungus Cryptococcus neoformans is a budding yeast that, in the host lung, switches to an unusual morphotype termed the Titan cell. Titans are large, polyploid, have altered cell wall and capsule, and produce haploid daughters. Their size prevents engulfment by phagocytes, yet they are linked to dissemination and altered immune response. Despite their important influence on disease, replicating the yeast-to-Titan switch in vitro has proved challenging. Here we show that Titans are induced by host-relevant stimuli, including serum and bronchio-alveolar lavage fluid. We identify bacterial peptidoglycan as a relevant inducing compound and predict an in vivo Titan defect for a clinical isolate. Genes regulating in vivo Titanisation also influence in vitro formation. Titanisation is a conserved morphogenic switch across the C. neoformans species complex. Together, we show that Titan cells are a regulated morphotype analogous to the yeast-to-hyphal transition and establish new ways to study Titans outside the host lung.

microbiology↗