Characteristics of Mycobacterium tuberculosis serine protease Rv1043c in enzymology and pathogenicity in mice

The serine proteases of Mycobacteria tuberculosis(Mtb)are important contributors to the process of bacterial invasion and its pathogenesis.In the present study,we systematically characterized the role of the Rv1043c protein in Mycobacterium infection by purifying the Rv1043c protein in Escherichia coli and constructing a Mycobacterium smegmatis(Msg)strain overexpressing Rv1043c(Msg_Rv1043c).We found that Rv1043c had serine protease activity and localized to the surface of Mtb.We determined that the optimal pH and temperature for the Rv1043c serine protease were 9.0 and 45°C,respectively.Moreover,the serine protease activity of Rv1043c was enhanced by divalent metal ions of Ca^(2+)and Mg^(2+).Site-directed mutagenesis studies demonstrated that the serine 279 residue in Rv1043c plays a catalytic role.Additionally,mouse model studies confirmed that Rv1043c significantly enhanced the survival of Msg in vivo,induced pulmonary injury and lung cell apoptosis,and promoted the release of pro-inflammatory cytokines interleukin-1βand interleukin-6 in mice.This study presents novel insights into the relationship between mycobacterial serine protease and the pathogenesis of the disease.

Comparative Study on the Immunogenicity between Recombinant MS-Sj26GST Vaccine and Recombinant BCG-Sj26GST Vaccine in Schistosoma japonicum

The BALB/c mice were immunized with rMS Sj26GST and rBCG Sj26GST vaccine in Schistosoma japonicum by subcutaneous injection After they were immunized for 8 weeks, the eyeballs were removed to get blood and macrophages of abdominal cavity and spleen cells were harvested The lymphocytic stimulating index (SI) was used to measure the cellular proliferating ability and NO release was used to measure the phagocytic activity of the macrophages By using ELISA kit, the levels of interleukin 2 (IL 2) and interferon γ (IFN γ) in serum and the splenic lymphocytic cultured supernatant were detected The results showed that after the mice were immunized with 10 6 CFU of rMS Sj26GST and rBCG Sj26GST vaccine separately by subcutaneous injection, proliferating ability of splenic lymphocytes in the mice showed no difference ( P >0 05), but both were significantly increased as compared with that in the control group( P <0 05); The contents of NO in the intraperitoneal macrophages of rMS Sj26GST vaccine group were significantly lower than in the control group ( P <0 001) and rBCG Sj26GST vaccine group ( P <0 01); The levels of serum IL 2 in the rMS Sj26GST vaccine group were significantly increased as compared with that in the control group ( P <0 001), vector group ( P <0 01) and rBCG Sj26GST vaccine group ( P <0 05); The contents of serum IFN γ in the rMS Sj26GST vaccine group were significantly increased as compared with that in the control group ( P <0 01) and rBCG Sj26GST vaccine group ( P <0 05) The contents of IFN γ in the cultured supernatant were significantly lower than those of rBCG Sj26GST vaccine group ( P <0 001), but were significantly increased as compared with that in the control group ( P <0 01) It was indicated that both vaccines could enhance the immune response of the mice, but rMS Sj26GST vaccine had stronger immunogenicity than rBCG Sj26GST vaccine

Siderochelins with anti-mycobacterial activity from Amycolatopsis sp. LZ149

Three new compounds, namely siderochelins D （2）, E （3）, and F （4）, together with one known siderochelin A （1）, were isolated from Amycolatopsis sp. LZ149 and elucidated by spectroscopic analyses includinglD- and 2D-NMR and X-ray single crystal diffraction. Compounds 1-3 showed antibacterial activity against Mycobacterium smegmatis.