Abstract:Objective To evaluate the role of PA1864 gene in the virulence and pathogenicity of Pseudomonas aeruginosa (PA). Methods Difference in virulence phenotype and pathogenicity between wild type (PAO1) and PA1864 gene knockout strain (△PA1864) which acutely infected mice lung or A549 lung cancer cells was compared, including the survival rate of mice, pulmonary edema, tissue damage, cell viability, secretory virulence factors of PAO1 and △PA1864 strains, type Ⅲ secretion system (T3SS) of toxic protein and quorum sensing(QS) system and so on. Results When PA1864 gene was knocked out, pathogenicity and cytotoxicity of bacteria to host decreased, bacterial swimming motility and expression of T3SS-related proteins (ExoS, PcrV) were down-regulated, while synthesis of pyocyanin increased, synthesis of signal molecules in quinolone QS system increased. Conclusion PA1864 gene can promote PA virulence, and this regulation may be related to quinolone QS system.