China Animal Husbandry and Veterinary Medicine ›› 2024, Vol. 51 ›› Issue (5): 2027-2036.doi: 10.16431/j.cnki.1671-7236.2024.05.024

• Preventive Veterinary Medicine • Previous Articles     Next Articles

Influence of Coexistence of LIPI-3 and LIPI-4 on Virulence of Pathogenic Listeria monocytogenes

QIAN Ruixuan2, LI Nan2, KANG Lichao3, MA Xun2, LIU Caixia2, SHI Weidi2, KOU Lijun2, REN Huijie2, QI Yatao2, YIN Zhongke2, LIU Lu2, WANG Jing2, WANG Zhengrong1, JIANG Jianjun2   

  1. 1. State Key Laboratory of Genetic Improvement and Health Breeding of Sheep, Xinjiang Academy of Agricultural and Reclamation Sciences, Shihezi 832000, China;
    2. College of Animal Science and Technology, Shihezi University, Shihezi 832000, China;
    3. Institute of Agricultural Quality Standards and Testing Technology, Xinjiang Academy of Agricultural and Reclamation Sciences, Shihezi 832000, China
  • Received:2023-11-06 Online:2024-05-05 Published:2024-04-28

Abstract: 【Objective】 This study was aimed to explore the impact of the coexistence of LIPI-3 and LIPI-4 on the virulence of Listeria monocytogenes (LM),reveal their potential regulatory effects on bacterial virulence,and lay a foundation for further research on the pathogenic mechanisms of LM.【Method】 LM928 (possessing LIPI-4 present) and LM873 (possessing both LIPI-3 and LIPI-4) were used as research objects to monitor the adhesion and invasion of two strains by infecting HCMEC/D3 cells.The effect of two strains on the median lethal dose (LD50) of chicken embryos were evaluated by chicken embryo infection test.The hemolytic activity of two strains were determined using hemolysis test.The apoptosis of HCMEC/D3 cells was analyzed using flow cytometry to evaluate the ability of two strain to induce cell apoptosis.The transcriptional differences of virulence genes between two strains under BHI culture conditions and post-infection of HCMEC/D3 cells were compared using Real-time quantitative PCR.【Result】 There was no significant difference of adhesion rates between LM928 and LM873 strains (P>0.05).The invasion rate of LM928 strain was extremely significantly higher than that of LM873 strain (P<0.01).The LD50 of LM873 strain was approximately 1 000 times that of LM928 strain.The hemolytic values of LM928 and LM873 strains were 24 and 23,respectively.The apoptosis rate induced by LM928 strain at 24 and 48 h post-infection were significantly or extremely significantly higher than that of LM873 strain (P<0.05 or P<0.01),while there was no significant difference of the apoptosis rate between LM873 strain and control group (P>0.05).When cultured in BHI culture,compared with LM928 strain,the transcription levels of virulence genes mpl,inlB,inlC,inlP,actA,plcA,plcB and sigB in LM873 strain were significantly or extremely significantly upregulated (P<0.05 or P<0.01),and the transcription levels of hly,inlA and iap genes were extremely significantly or significantly downregulated (P<0.01 or P<0.05).After infecting HCMEC/D3 cells,compared with LM928 strain,the transcription levels of virulence genes inlP,actA,plcA,plcB and prfA in LM873 strain were significantly or extremely significantly upregulated (P<0.05 or P<0.01),and the transcription levels of hly,mpl,inlA,inlB,inlC and iap genes were extremely significantly downregulated (P<0.01).【Conclusion】 The coexistence of LIPI-3 and LIPI-4 reduced the virulence of LM,which holded significant implications for further research into the molecular mechanisms and complex interactions of LIPI-3 and LIPI-4 in bacterial virulence regulation.

Key words: Listeria monocytogenes (LM); LIPI-3; LIPI-4; virulence; virulence gene

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