Adhesion, invasion and intracellular growth ability of Legionella dumoffii in alveolar epithelial cells / 中国人兽共患病学报

ABSTRACT

In this study,the L.dumoffii TEX-KL (ATCC 33343),L.dumoffii NY23 (ATCC 33279) and L.pneumophila philadelphila-1 (ATCC 33155) strains were used to explore the adhesion,invasion and intracellular growth ability in the epithelial cells.Approximately 1× 108 bacteria were pelleted,resuspended,and diluted (1 ∶ 10) in RPMI 1640 tissue culture medium.The bacteria were then added to A549 cells (1 × 105 per well) in 24-well plates to give a multiplicity of infection (MOI) of about 100.The Gimenez staining and colony counting methods were used for the determination of the strain adhesion,invasion and intracellular growth ability.It was found that in vitro growth ability of L.pneumophila philadelphila-1,L.dumoffii TEX-KL and L.dumoffii NY23 strains had no significant difference.For in vivo assay,there was also no significant difference in adhesion ability of these strains.However,the CFU counts of L.dumoffii TEX-KL strain invaded into A549 cells was 1 000 times higher than that of the other two strains.Compared with L.pneumophila philadelphila-1 and L.dumoffii NY23 strains,L.dumoffii TEX-KL strain has higher invasion ability and,therefore,higher intracellular growth ability.