Project description:MicroRNAs (miRNAs) play important roles by regulating the expression of target genes in plant and animal. However, little known about mechanism of fungal miRNA-like RNAs (milRNAs) regulating target gene restricts their functional exploration. In this study, multiple omics were used to identify the milRNAs and their target genes in a phytopathogenic fungus Valsa mali. Many candidate pathogenic factors were found to be regulated by milRNA-directed cleavage way. Absence or downregulated expression of Vm-milRNAs promote expression of candidate pathogenic factors during V. mali infection. Vm-milR16 is a significantly downregulated milRNA during V. mali infection, resulting in significantly upregulated expression of three target genes: VmSNF1, VmDODA, and VmHy1. Overexpression of Vm-milR16 significantly reduces the pathogenicity of V. mali. And all the three target genes of Vm-milR16 are required for the full pathogenicity of V. mali. Further analysis revealed that VmSNF1 regulates the pathogenicity by affecting the expression of pectinase genes during V. mali infection. And all the three target genes are essential for oxidative stress response during V. mali-host interaction. Vm-milRNAs may help V. mali to intelligently use limited resources and adaptively regulate pathogenicity by enhancing expression of pathogenic factors and fitness during infection.
Project description:Nontyphoidal Salmonella (NTS) infections cause significant illness worldwide, particularly in sub-Saharan Africa, where invasive NTS (iNTS) disease leads to life-threatening bloodstream infections. Developing vaccines to prevent iNTS is a public health priority, but progress has been slow due to gaps in understanding how these bacteria cause disease and how the immune system responds. Controlled human infection models (CHIMs) can accelerate vaccine development by allowing detailed investigation of infection biology in a controlled setting. This study describes the selection, production, and detailed characterisation of two Salmonella Typhimurium strains for the first-in-human iNTS CHIM. The strains – one associated with diarrhoeal disease and the other with bloodstream infections – were chosen based on their global relevance and comprehensive prior testing. We confirmed their stability, antibiotic susceptibility, and behaviour in conditions mimicking the human gut. Importantly, we found that sodium bicarbonate, used to neutralise stomach acid before infection, does not alter bacterial virulence. These findings ensure that the selected strains accurately represent real-world infections while maintaining safety for use in human trials. This CHIM will be a valuable platform for testing new iNTS vaccines and improving our understanding of NTS infections.
