Negi, V. D. | bioRxiv Science

bioRxiv2023

Clustered Regularly Interspaced Short Palindromic Repeats-Cas system regulates Salmonella virulence

ObjectivesInvestigating the type 1-E CRISPR-Cas-mediated regulation of Salmonella pathogenesis. MethodsWe assessed the pathogenicity of the wild-type and CRISPR-Cas knockout strains using infection models. The mechanisms were elucidated using antimicrobial assays and expression analysis. ResultsCRISPR-Cas knockout strains were defective in invasion and proliferation in intestinal epithelial cells and macrophages. However, proliferation defects were not observed in the Gp91phox-/- macrophages, suggesting the systems role in antioxidant defence. The knockout strains show hampered colonization in in-vivo infection models, possibly due to increased sensitivity against innate immune barriers like antimicrobial peptides, complement proteins and oxidative stress. The expression studies of various virulence regulators: pmr genes, anti-oxidant genes, SPI-1 and SPI-2 encoded master regulators, and effectors showed repressed expression in the knockout strains. Some of these genes could be directly regulated by the CRISPR-spacers owing to partial complementarity between the sequences. ConclusionOverall, our study shows that the CRISPR-Cas system positively regulates Salmonella pathogenesis by regulating the expression of different virulence factors.

microbiology↗

bioRxiv2023

AWC mediated behavioral plasticity in C. elegans against Salmonella Typhimurium infection

Soil-dwelling nematode Caenorhabditis elegans (C. elegans) is widely found in close vicinity with different types of microbes, including bacteria, fungus, viruses, etc. However, sensing environmental stress, they often undergo a dormant state called dauer for better survival. Our current study aims to decipher chemosensory responses of worms under Salmonella Typhimurium (WT-STM) infection and how bacterial gene modulating worms chemosensory system to mediate dauer larvae development. We initially observed the olfactory preference of C. elegans toward the pathogenic WT-STM. Although prolonged exposure showed enhanced lawn occupancy of worms in fepB mutant Salmonella strain with better associative learning response compared to WT-STM counterpart. We also found strong participation of AWC neuron for sensing {Delta}fepB strain and mediating worms behavioral plasticity. Overall out study implying a relationship between chemosensory neurons and bacteria emitted signals alter worms behavioral plasticity which help us to understand complex scenario of host-pathogen interaction.

microbiology↗