Jingnan Lv, Jie Zhu, Ting Wang, Xiaofang Xie, Tao Wang, Zhichen Zhu, Liang Chen, Fengyun Zhong, Hong Du
Hypervirulent (hvKP) is an evolving infectious pathogen associated with high mortality. The convergence of hypervirulence and multidrug resistance further challenges the clinical treatment options for infections. The QseBC two-component system (TCS) is a component of quorum-sensing regulatory cascade and functions as a global regulator of biofilm growth, bacterial motility, and virulence in . However, the functional mechanisms of QseBC in hvKP have not been reported, and we aim to examine the role of QseBC in regulating virulence in hvKP strain ATCC43816. The CRISPR-Cas9 system was used to construct , , and knockout in ATCC43816. No significant alterations in the growth and antibiotic susceptibility were detected between wild-type and mutants. The deletion of led to an increase of biofilm formation, resistance to serum killing, and high mortality in the model. RNAseq differential gene expression analysis exhibited that gene-associated biofilm formation (), bacterial type VI secretion system (), and biosynthesis of siderophore () were significantly upregulated in comparison with the wild-type control. In addition, , (encode OB-family protein), and AraC family transcriptional regulator IT767_23090 genes showed highest expressions in the absence of QseC, which might be related to increased virulence. The study provided new insights into the functional importance of QseBC in regulating the virulence of hvKP.
