Objective To explore the action mechanism of tauroursodeoxycholic acid(TUDCA)promoting intracellular clearance of Burkholderia pseudomallei(B.pseudomallei)in RAW264.7 macrophages.Methods After TUDCA of different concentrations were used to treat RAW264.7 cells pre-infected with B.pseudomallei for 8 h or not,flow cytometry was applied to detect the apoptosis of the infected and control cells.In addition,another endoplasmic reticulum stress(ERS)inhibitor 4-PBA was used to detect the apoptosis and proliferation of host cells after B.pseudomallei infection with Annexin-V/PI double staining and MTT cell proliferation assay.Furthermore,after transfected with CHOP siRNA,Western blotting and flow cytometry were employed to detect the effect of TUDCA on the expression levels of Caspase-3 and Caspase-12 and the changes in apoptotic rate after B.pseudomallei infection,respectively.Finally,the effect of TUDCA on intracellular multiplication of infected RAW264.7 cells were observed to estimate the CFU value in the presence and absence of CHOP siRNA.Results Under different concentrations of TUDCA,100 or 200 μmol/L TUDCA significantly reduced B.pseudomallei-induced apoptosis in RAW264.7 cells(P＜0.05).Meanwhile,both TUDCA and 4-PBA treatment could decrease the apoptosis induced by B.pseudomallei infection by ERS(P＜0.05).Further,the expression levels of Caspase-3 and Caspase-12 were obviously increased after B.pseudomallei infection compared with uninfected groups,but their expression levels in the siCHOP group was significantly lower than that in the siC group.Besides,flow cytometry also showed that TUDCA could reduce apoptosis induced by B.pseudomallei infection(P＜0.05),but no significant effect of TUDCA on apoptosis was observed under CHOP knockdown.Finally,intracellular CFU assay indicated that TUDCA treatment promoted the host cell clearance of B.pseudomallei(P＜0.05),but no such effect was observed in siCHOP group.Conclusion In B.pseudomallei infected RAW264.7 cells,TUDCA promotes the intracellular clearance of the bacteria by inhibiting ERS-induced apoptosis.

Objective To express recombinant Burkholderia pseudomallei(B.pseudomallei)type Ⅲ secretion system BipD protein,prepare its polyclonal antibodies and verify their immunological traits.Methods The recombinant pET-28a-BipD plasmid was generated,and the pET-28a-BipD-carried E.coli BL21(DE3)bacteria were induced with isopropyl-β-d-thiogalactoside(IPTG)to express recombinant BipD(rBipD)protein.The rBipD was obtained by affinity chromatography using His Trap column,then mixed with Fredrick's adjuvant to immunize BALB/c mice by intraperitoneal injection in order to obtain anti-rBipD polyclonal antibodies.The immunoreactivity of rBipD was detected by Western blot assay using rabbit anti-melioidosis serum and the serum from melioidosis patients.The immunogenicity of rBipD was evaluated using Western blotting and immunofluorescence staining.Finally,rBipD was used to establish an indirect ELISA to detect serum antibodies of clinical melioidosis patients.Results The recombinant plasmid pET-28a-BipD was successfully constructed and transformed into E.coli BL21(DE3)to induce rBipD expression with IPTG treatment.The obtained rBipD had a relative molecular weight of 36×103 and a purity of 95.4％,and had good immunogenicity and immunoreactivity.It could induce the production of specific antibodies after immunizing mice,and mouse polyclonal antibodies against rBipD were prepared with the titer of 1∶512 000.rBipD of 5.0 μg/mL produced specific immune response with the serum of melioidosis patients,but had no specific reaction with the serum of tuberculosis patients,with statistical difference(P＜0.01).Conclusion rBipD with immunological activity is successfully prepared and purified,and its polyclonal antibodies are also developed,which provide a good tool for clinical immunological diagnosis and study of immune mechanism of B.pseudomallei infection.

Objective To analyze the mechanism that Hcp1 protein in type Ⅵ secretion system of Burkholderia pseudomallei(B.pseudomallei)mediates the formation of multinucleated giant cells(MNGCs)when host cells are infected by the bacterium.Methods The mutant strain(BPC006 Δhcp1)and complementation strain(BPC006 Δhcp1::hcp1)were constructed by homologous recombination and plasmid complement technology,respectively.After RAW264.7 cells were infected with B.pseudomallei,the localization of Hcp1 in host cells was analyzed by immunofluorescence staining.The localization was further verified by cytoplasmic-membrane isolation in 293T cells after transfecting pCDNA4.1-Hcp1.The biological significance and effect of Hcp1 were explored by the anti-Hcp1 polyclonal antibody blocking and the formation of MNGC was detected by Giemsa staining.Results Western blotting showed that BPC006 Δhcp1 could not express Hcp1,while BPC006 Δhcp1::hcp1 restored Hcp1 expression.The above results proved that the mutant and complement strains were successfully constructed.Both cellular immunofluorescence co-localization and cytoplasmic-membrane isolation experiments showed that Hcp1 localized to host cell membranes.Last but not least,compared with the control group,anti-Hcp1 polyclonal antibodies inhibited the formation of MNGC(P＜0.01).Conclusion Hcp1 protein in type Ⅵ secretion system of B.pseudomallei is able to translocate to the RAW264.7 cell membranes and plays an important role in the formation of MNGCs.

Bacteria play an important role in human health and disease. Their biological functions are often related to the glycans attached to the protein surface. In recent years, the glycosylation modification of bacterial proteins has attracted increasingly widespread attention. With the continuous development of synthetic biology and the in-depth research on glycosylation modification systems, some modification systems have been applied in engineered bacteria to play the role of protein modification independently, making it possible to "customized glycoproteins" . This paper reviewed the current status of research on the basic components, types and pathways of bacterial protein glycosylation modification as well as the biological function and application.

The research of structural biology is closely related to the field of biotechnology.Carrying out the second class of structural biology will be helpful in learning theoretical knowledge of biotechnology and in improving the teaching quality.Based on our experiences of carrying out the second classroom activities among students majoring in biotechnology,we believe that the selected teaching contents,reasonable classroom design,sufficient preparation before the class,flexible teaching methods and objective after-school summaries are essential for improving the teaching quality.

Objective To analyze the combination characteristics between Tir-IBD( intimin binding domain) and its ligand intimin or mutant intiminN916Y of EHEC O157 ∶H7.Methods The gene of TirIBD (tir-ibd) from EHEC O157 ∶H7 chromosome was cloned into pMD18-T vector.Thereafter,the amplified gene was cloned into prokaryotic expression plasmid pET-21 a (+).The recombinant pasmid pET-21 a( +)-tir-ibd was transformed into E.coli BL21 (DE3).After inducement,the protein Tir-IBD was successfully expressed and analyzed with SDS-PAGE and Western blot.It was purified by affinity chromatography and ionexchange chromatography and was coupled on the Ni-NTA chip of BIACore 3000.Then the ligand intimin and mutant intiminN916Y were flow through the chip and their combination characteristics were detected.Results In the present study,the gene of Tir-IBD(tir-ibd) was successfully cloned into pET-21a(+).The results of SDS-PAGE and Western blot assay showed that the protein was successfully expressed,which accounts for 15％ of total expression products,and its molecular weight was about 10×103.The purity was above 95％ after purification.After coupled on the Ni-NTA chip of BIACore 3000,their combination characteristics with ligand intimin and mutant intiminN916Y were successfully detected.The equilibrium binding constants Ka was obtained by fitting the data with the BIACore evaluation program ( Version 4.1 ).The result showed that the combination characteristics between Tir-IBD and intimin have some difference compared with that of mutant intiminN916Y and the difference is temperature dependent.Conclusion Tir-IBD of EHEC O157 ∶H7 was successfully constructed and purified.The method to analyze the combination characteristics between Tir-IBD and its ligand intimin or mutant was established.The combination characteristics between Tir-IBD and intimin or mutant intiminN916Y have some temperature dependent difference and the mutated amino acids residue is crucial for their receptor-ligand binding.

Objective To clone the gene encoding protein of EspA and Stx2B from EHEC OI57:H7 by DNA recombinant technology, construct prokaryotic expression vector pET-28a ( + )-espAstx2B, express fusion protein of EspA-Stx2B and to analyze the biological and immunological characteristics of the fusion protein. Methods the sequence encoding the protein of EspA and Stx2B was amplified by PCR from the enterohemorrhagic Escherichia coli strain. The amplified products were connected with linker by recombinant technology and cloned into pET-28a( + ) vector. The vector was then transferred to the host cells E. Coli BL21 strain (DE3). Following, the protein expression was induced by IPTG. The expression quantities and style of fusion protein was then determined by SDS-PAGE. Its immunoreactivity was analyzed by Western blot. Finally, BALB/c mice were injected with the preliminarily purified recombination protein EspA-Stx2B, then oral challenged these mice with EHEC O157-SMR2 and counteracted toxic substances with O157 ultrasonic supernatant. Results The determination of the sequence encoding of the espA-stx2B fusion gene has 100% of consistency with the sequence from GenBank Sakai strain and contrivable linker. This fusion protein EspA-Stx2B was expressed as inclusion body formation and the percentage is approximately 40%. Western blot suggested the fusion protein has excellent immunoreactivity. Titer of antiserum of the mice to EspA-Stx2B increased evidently. EspA-Stx2B could not decrease bacterial number attached to the intestinal tract of mice based on fecal shedding of Oi57 in mice. In the test of death of BAI,B/c causing by conteracting toxic substances with O157 ultrasonic supernatant, immunoprotection of EspA-Stx2B rate was 66.7%. Conclusion A recombinant plasmid that has high performance on expression of EspA-Stx2B prorein was successfully constructed in present study, and the fusion protein has excellent immunoreactivity and immunogenicity. EspA-Stx2B could not decrease bacteria] number attached to the intestinal tract of mice based on fecal shedding of O157 in mice, but evidently decrease the mortality rate of the mice. The antiEspA and anti-Stx2B had immunoprotection effect by different means. These results may provide the foundation for the further development on EHEC O157:H7 double subunit vaccine.

Objective To investigate immunoprophylactic potential of genetic engineering vaccines of enterohaemorrhagie Escherichia coli O157:H7 in BALB/c mice after immunization with these vaccines. Methods Sixty BALB/c mice (3 weeks old) were randomized averagely into 5 groups. Group 1-3 were im-munized respectively with IntiminC300, Stx2B and HIyAN436, group 4 with a combination of these three vaccines, and group 5 with PBS. Each mouse was immunized with vaccine(100 μg)and Al(OH)3 adjuvant (100 μg) for 3 times. After 7 d of the second and third immunization, serum of each mouse was collected and the different antibodies were detected. After 10 d of the last immunization, all mice were given drinking water containing streptomycin for 3 d before and following oral challenge with O157:H7 (109 CFU), and treated with clinical, microbiological and pathological examination. Results The three vaccines elicited high titer antiserum, and some mice were died after infection with O157. The livability of group 1-4 was re-spectively 73%, 64%, 36% and 91%. And these vaccines depressed fecal and colon shedding with O157. Condusion IntiminC300, Stx2B and HIyAN436 have certain protective efficacy for infection of O157, and combined immunization was more effective than single vaccine.

OBJECTIVETo express a fusion protein of Neisseria gonorrhoeae with a mucosal adjuvant.

METHODSThe gene coding Loop VI-VIII(PL678) of porin, an out-membrane protein of Neisseria gonorrhoeae, was obtained by PCR. It was inserted into a plasmid fused with subunit B of heat labile enterotoxin. The recombinant was transformed in E. coli. The expression of fusion protein was analysed by ELISA, SDS-PAGE and Western-blot.

RESULTFusion protein with LTB was successfully expressed, and displayed both the ability of binding GM1 and the reactogenicity with polyclonal antibodies against Neisseria gonorrhoeae.

CONCLUSIONThe expression of fusion protein laid a foundation for the study of the intramolecular vaccine against Neisseria gonorrhoeae.

Bacterial Outer Membrane Proteins ; biosynthesis ; Bacterial Toxins ; biosynthesis ; Bacterial Vaccines ; immunology ; Enterotoxins ; biosynthesis ; Escherichia coli ; genetics ; Escherichia coli Proteins ; Neisseria gonorrhoeae ; chemistry ; immunology ; Polymerase Chain Reaction ; Recombinant Fusion Proteins ; biosynthesis ; Vaccines, Synthetic ; immunology

MicroRNAs (miRNA) are a newly discovered class of endogenous,evolutionarily conserved small noncoding RNAs involved in posttranscriptional gene regulation. Functionally speaking,miRNAs act as key regulators in a wide variety of biological processes,including cell proliferation,cell differentiation,apoptosis,metabolism,developmental timing,signal transduction and tumor. Recent publications have provided compelling evidence that a range of miRNAs are involved in the regulation of immunity,including the innate immunity,proliferation of monocytes and neutrophils,the development and differentiation of B and T cells,infection and immunity,and the release of inflammatory mediators. In this review,we examine what is presently known of the function and mechanism of these miRNAs in the regulation of the innate and acquired immune response.