Objective:To investigate the effect and preliminary mechanism of hypervirulent Klebsiella pneumoniae (hvKP) on the immune response to sepsis induced by liver abscess in mice. Methods:C57BL/6 mice were intraperitoneally injected with hvKP strain NTUH-K2044 or classical Klebsiella pneumoniae (cKP) strain HS11286 suspension to prepare the model of sepsis. The survivals rates of mice within 24 h were recorded. HE staining was used to observed the inflammatory cell infiltration in mouse liver tissues. The levels of neutrophil marker lymphocyte antigen 6G (Ly6G) in mouse liver tissues were detected by immunohistochemistry. The activity of reactive oxygen species (ROS) in mouse liver macrophages and peripheral blood monocytes was measured by ROS assay kit. The activation of p105/p50 and p65 in NF-κB signaling pathway in mouse liver macrophages and peripheral blood monocytes was detected by Western blot. The expression of IL-1β, IL-6 and TNF-α at mRNA and protein levels in mouse liver macrophages and peripheral blood monocytes were detected by qRT-PCR and ELISA, respectively. One-way analysis of variance and t test were used for statistical analysis. Results:Compared with cKP, hvKP infection could induce C57BL/6 mice to develop obvious liver abscess with massive inflammatory cell infiltration. Moreover, the level of Ly6G in liver tissues was significantly higher in hvKP-infected mice than in cKP-infected mice ( P<0.000 1), but the survival rate of hvKP-infected mice was significantly lower than that of cKP-infected mice ( P<0.000 1). hvKP significantly promoted the ROS activity ( P<0.000 1) and enhanced the phosphorylation of p105/p50 and p65 in NF-κB signaling pathway in mouse liver macrophages and peripheral blood monocytes as compared with cKP ( P<0.001). The expression of IL-1β, IL-6 and TNF-α at mRNA and protein levels in mouse liver macrophages and peripheral blood monocytes were significantly higher in hvKP-infected mice than in cKP-infected mice ( P<0.001). Conclusion:hvKP can promote the development of liver abscess and induce sepsis in mice.

Objective:To investigate the effect and preliminary mechanism of hypervirulent Klebsiella pneumoniae (hvKP) on the immune response to sepsis induced by liver abscess in mice. Methods:C57BL/6 mice were intraperitoneally injected with hvKP strain NTUH-K2044 or classical Klebsiella pneumoniae (cKP) strain HS11286 suspension to prepare the model of sepsis. The survivals rates of mice within 24 h were recorded. HE staining was used to observed the inflammatory cell infiltration in mouse liver tissues. The levels of neutrophil marker lymphocyte antigen 6G (Ly6G) in mouse liver tissues were detected by immunohistochemistry. The activity of reactive oxygen species (ROS) in mouse liver macrophages and peripheral blood monocytes was measured by ROS assay kit. The activation of p105/p50 and p65 in NF-κB signaling pathway in mouse liver macrophages and peripheral blood monocytes was detected by Western blot. The expression of IL-1β, IL-6 and TNF-α at mRNA and protein levels in mouse liver macrophages and peripheral blood monocytes were detected by qRT-PCR and ELISA, respectively. One-way analysis of variance and t test were used for statistical analysis. Results:Compared with cKP, hvKP infection could induce C57BL/6 mice to develop obvious liver abscess with massive inflammatory cell infiltration. Moreover, the level of Ly6G in liver tissues was significantly higher in hvKP-infected mice than in cKP-infected mice ( P<0.000 1), but the survival rate of hvKP-infected mice was significantly lower than that of cKP-infected mice ( P<0.000 1). hvKP significantly promoted the ROS activity ( P<0.000 1) and enhanced the phosphorylation of p105/p50 and p65 in NF-κB signaling pathway in mouse liver macrophages and peripheral blood monocytes as compared with cKP ( P<0.001). The expression of IL-1β, IL-6 and TNF-α at mRNA and protein levels in mouse liver macrophages and peripheral blood monocytes were significantly higher in hvKP-infected mice than in cKP-infected mice ( P<0.001). Conclusion:hvKP can promote the development of liver abscess and induce sepsis in mice.

To provide the basis for preparation of diagnostic kits and vaccines in Toxoplasma gondii infection, the gene coding for the qualified recombinant p30 protein (SAG1) of this parasite was amplified by PCR, and the amplified gene was cloned into prokaryotic expression vector pET-30a(+) to construct the recombinant plasmid, and then transformed to E.coli DH5α. The positive recombinant plasmid was screened by PCR and double enzymes digestion, and the nucleotide sequence of p30 gene was determined by automated DNA sequencing. Meanwhile, the identified recombinant plasmid was transformed to E.coli BL21(DE3) with the expression of p30 on bacteria induced by IPTG and the expressed protein was identified by SDS-PAGE. The protein obtained was then further purified and refolded, and its biological activity was checked by Western blotting. It was shown that the size of the amplified gene was 750 bp with molecular weight of 30 ku, and this protein could specifically react with monoclonal antibody against p30 protein.