The KbvR regulator contributes to capsule production, outer membrane protein biosynthesis, anti-phagocytosis and virulence in Klebsiella pneumoniae.

Klebsiella pneumoniae is an opportunistic pathogen that mostly affects patients with weakened immune systems, but a few serotypes (especially K1 and K2) are highly invasive and result in systemic infection in healthy persons. The ability to evade and survive the components of innate immune system is critical in infection. To investigate the role and mechanism of transcription regulator KP1_RS12260 (KbvR) in the virulence and defence against innate immune response, the deletion mutant and complementary strains of kbvR were constructed. The in vivo animal infection assay and in vitro anti-phagocytosis assay demonstrate the K. pneumoniae KbvR is an important regulator that contributes to the virulence and the defence against phagocytosis of macrophage. The transcriptome analysis and phenotype experiments demonstrated the deletion of kbvR decreased production of capsular polysaccharide (CPS) and biosynthesis of partly outer membrane proteins. The findings suggest that KbvR is a global regulator that confers pathoadaptive phenotypes, which provide several implications for improving our understanding of the pathogenesis of K. pneumoniae.