OBJECTIVETo study the changes in biological behaviors of meningitis E. coli K1 strain E44 after deletion of polyphosphate kinase 1 (ppk1) gene and explore the role of ppk1 in the pathogenesis of E. coli K1-induced meningitis.

METHODSThe wild-type strain E. coli K1 and ppk1 deletion mutant were exposed to heat at 56 degrees celsius; for 6 min, and their survival rates were determined. The adhesion and invasion of the bacteria to human brain microvascular endothelial cells (HBMECs) were observed using electron microscopy and quantitative tests. HBMECs were co-incubated with wild-type strain or ppk1 deletion mutant, and the cytoskeleton rearrangement was observed under laser scanning confocal microscope.

RESULTSThe survival rate of the ppk1 deletion mutant was significantly lower than that of the wild-type strain after heat exposure. The ppk1 deletion mutant also showed lowered cell adhesion and invasion abilities and weakened ability to induce cytoskeleton rearrangement in HBMECs.

CONCLUSIONSppk1 gene is important for E.coli K1 for heat resistance, cell adhesion and invasion, and for inducing cytoskeletal rearrangement in HBMECs.