Impact of yihO/Q deletion in O-Antigen capsule formation, environmental stress mitigation, and intracellular virulence, survival and replication of Salmonella Typhimurium

This study characterized the involvement of yihO and yihQ of yih operon associated with O-antigen capsule formation, in phenotypic characteristics, intracellular survival, and virulence in Salmonella Typhimurium (ST). Bacterial fitness screening of the ?yihO, ?yihQ, and ?yihO/Q ST mutants showed impairment in biofilm formation, motility, starvation, and stress survival. In vitro studies using phagocytic and non-phagocytic cells revealed a significant decrease in bacterial invasion and intracellular replication, particularly by the ?yihO and ?yihO/Q ST which correlated with the lack of proliferation ability in vivo as observed in the liver and spleen colonization. Transcriptome analysis of the ?yihO mutant further revealed the downregulation of several genes associated with key processes such as flagellar assembly, Salmonella infection, and T3SS protein secretion such as SPI-1 and SPI-2. This evidence expands the role of yihO as an essential gene for maintaining Salmonella's environmental resilience and virulence. Overall design: To investigate the possible regulatory role of yihO in Salmonella Typhimurium, the gene was deleted by lambda red recombination method; differentially expressed gene analysis was performed against the Salmonella Typhimurium wild-type using data obtained from RNA-seq