Transcriptomic profile of BpsR4 and its roles in stress response, antibiotic susceptibility, biofilm formation, and pathogenesis in Burkholderia pseudomallei

Objective: The study investigated the role of the quorum sensing (QS) regulator BpsR4 in the physiology and virulence of Burkholderia pseudomallei strain K96243. Methods: A B. pseudomallei bpsR4 knockout mutant (ΔbpsR4) was constructed, and its gene expression profile was compared with that of the wild-type (WT) K96243 strain using RNA sequencing. In vitro assays were conducted to assess growth rates, stress responses, antibiotic sensitivity, motility, and biofilm formation. Ex vivo pathogenicity was evaluated using a human skin fibroblast infection model, and in vivo virulence was assessed in the Galleria mellonella model. Results: bpsR4 deletion led to significant transcriptional reprogramming, including the downregulation of genes involved in iron acquisition, sulfur metabolism, oxidative stress response, and redox homeostasis and upregulation of genes linked to motility, chemotaxis, and membrane transport. ΔbpsR4 exhibited reduced tolerance to oxidative and heat stress and impaired biofilm formation but no significant change in motility. Additionally, ΔbpsR4 displayed decreased susceptibility to meropenem. In both in vitro and invertebrate infection models, the mutant demonstrated lower virulence than the WT strain. Conclusion: This study highlighted the involvement of BpsR4 in stress response, antimicrobial susceptibility, and virulence in B. pseudomallei. Targeting QS pathways, particularly BpsR4 signaling, might represent a promising strategy to develop anti-virulence therapies that enhance antibiotic efficacy and improve clinical outcomes in melioidosis.