Project description:In this study we are examining the paracrine effect induced by feline calicivirus (FCV) infection on stress granule (SG) accumulation. We provided an understanding of paracrine granules function and specificity through their affinity purification followed RNAseq to systematically analyse their RNA content.
Project description:We are here presenting a new paracrine induction of RNA granules by viruses. Infection by viruses imposes major stress on the host cell. In response to this stress, infected cells can induce several defence mechanisms, which include the activation of stress response pathways and the innate immune response. These often result in an inhibition of translation culminating in the assembly of cytoplasmic granules called stress granules (SGs). SGs assembly follows from liquid phase separation of aggregation-prone proteins such G3BP1 and TIA-1, leading to the sequestration of mRNAs. Because this threatens viral gene expression, viruses need to evade these stress response pathways to propagate. Using feline calicivirus (FCV), surrogate for norovirus, the main virus responsible for gastroenteritis outbreaks worldwide, we previously showed that FCV impairs SGs assembly by cleaving the scaffold protein G3BP1. Interestingly, we observed that uninfected bystander cells assembled G3BP1 granules, suggesting a paracrine response trigged by the infection. We now present evidence that virus-free supernatant generated from infected cells can induce the formation of RNA granules. We have characterised the dynamic of the granules assembly via confocal microscopy. Moreover, we provide an understanding of paracrine granules function and specificity through their affinity purification followed by proteomics and RNAseq analysis of their proteins and mRNAs content. This helps to define rules of assembly and novel functions for paracrine granules highlighting fundamental differences with canonical stress granules.
Project description:This study focuses on lung injury and related protein changes caused by feline calicivirus (FCV) infection, aiming to provide a theoretical basis for the diagnosis, treatment, and prognosis evaluation of FCV infection. First, we investigated the geographical distribution of 69 FCV strains from different countries in the NCBI database between 2020 and 2025, and found that China had a more severe infection situation. For the FCV-BJ616 and FCV-BJDX40 strains preserved in the laboratory, immunofluorescence showed that both strains could infect F81 cells, and HE staining revealed that they could induce strong pathological changes in feline lung tissue. Proteins were extracted from cat serum samples before and after infection for differential interaction analysis (DIA). Through quality control measures including correlation coefficient calculation, principal component analysis, and heat map visualization, the serum data demonstrated high quality and reproducibility. Differential protein expression and interaction analysis were conducted on serum samples from FCV-BJ616 and FCV-BJDX40 infections, revealing the number, overlap, and specificity of upregulated and downregulated proteins between the two groups, thereby identifying potential biological functional modules and protein interaction relationships. Further GO and KEGG enrichment analyses revealed significant differences between the datasets in multiple critical biological processes and signaling pathways. DEP analysis of candidate biomarkers identified significant upregulation of ACSL4 and ACSL5 in both serum groups, potentially associated with ferroptosis-induced lung damage, while S100A2 showed significant downregulation, suggesting its potential as a prognostic biomarker for FCV. Western blotting validation confirmed consistent expression patterns of ACSL4, ACSL5, and S100A2 with FCV, indicating that ACSL4 and ACSL5 may serve as potential serum biomarkers for FCV, while S100A2 could be utilized for FCV prognosis assessment.