[Comparison of the Effects of ILO and LLO in Helping Listeria Adhere, Invade Cell and Intracellularly Multiply]

Abstract

Objective: To study the primary function of ivanolysin O (ILO) and Listeriolysin O (LLO) and compare the effects of these two hemolysins in helping bacteria adhere, invade cell and intracellularly multiply.

Methods: The targeting plasmids carrying the upstream and downstream sequences of i-hly and lacZ gene sequence or hly gene sequence were constructed. Then two recombinant strains, the ILO deletion strain LIΔi-hly::lacZ and LLO compensative expressing strain LIΔi-hly::hly, were constructed by plasmid targeting recombinant technique. The adhesive and invasive ability of LIΔi-hly::hly, LI and LIΔi-hly::lacZ were evaluated in HepG2 cells, and their intracellular multiplication abilities were evaluated in RAW264.7 macrophages.

Results: Genome sequences of the recombinant strains were as expected. The adhesive rate of LIΔi-hly::i-hly LI and LIΔi-hly::lacZ were (3.43±0.82)%, (3.43±1.59)% and (3.41±1.12)% respectively, and the invasive rate were (1.74±0.46)%, (1.22±0.75)% and (1.39±0.46)% respectively. Difference in adhesive and invasive rates showed no significance. Among three strains, LIΔi-hly::lacZ showed the lowest intracellular proliferation rate, and LIΔi-hly::hly possessed the highest intracellular proliferation rate in RAW264.7 macrophages.

Conclusion: The intracellular multiplication ability of LI is related to ILO. Deletion of ILO induces a distinct decrease in intracellular multiplication for LI. Compared with ILO, LLO shows a stronger ability in helping the bacteria escape from the phagosome into the host cell cytosol.

Keywords: Intracellular multiplication; Ivanolysin O; Listeria ivanovii; Listeria monocytogenes; Listeriolysin O.