Purpose: The present study is aimed at investigating whether DesB contributes to the pathogenic activities in host cells, such as exotoxin production, hemolysis, cell invasion and intracellular replication.
Methods: For exotoxin production assay, HeLa cells were exposed to cell-free supernatant of wild type P. aeruginosa (WT) or its derived desB mutant, and exotoxins were indirectly quantified by cell viability assay. For invasion and intracellular replication assays, WT or desB mutant was inoculated in HeLa cells, and the efficiencies of invasion and intracellular replication of WT and desB mutant were compared. Hemolysis assay was performed by spotting overnight cultures of WT and mutants on blood-containing agar plate. In order to determine if desB controls the expression of plcH, a hemolytic phospholipase-encoding gene, expression of plcH in WT and desBmutant were compared by qRT-PCR.
Results: desB mutant had different efficiency in exotoxin production, invasion and intracellular replication in cells compared to WT. Furthermore, decrease in hemolysis was observed in desB mutant, but plcH expression had no difference between WT and desB mutant, indicating that reduced hemolysis in desB mutant is not attributed to plcH.
Significance: The results demonstrate that P. aeruginosa DesB have effect on pathogenesis-related behaviors in host cells, including exotoxin production, hemolysis, cell invasion and intracellular replication.