OBJECTIVETo investigate the functional relations between the putative proteins YpCD1.08, YpCD1.09, YpCD1.16 encoded in pCD1 plasmid of Yersinia pestis and its type III secretion system (T3SS).

METHODSMutants of YpCD1.08, YpCD1.09, YpCD1.16 were constructed using λ-Red recombinant system. The growth curves of the mutant strains cultivated in TMH medium with or without calcium at 26 °C and 37 °C were determined to analyze the low calcium response phenotype. The transcription levels of ΔYpCD1.08, ΔYpCD1.09, ΔYpCD1.16 in Yersinia pestis and the dependence to temperature were determined using real time RT-PCR after cultivation at 26 °C and 37 °C and extraction of RNA. A β-lactamases reporter system was adopted to study the influence of these genes on the translocation of effector YopE of T3SS.

RESULTSWhen grown in TMH medium without calcium at 26 °C and 37 °C, the growth curve of the YpCD1.08, YpCD1.09, YpCD1.16 mutants were similar to that of the wild-type strain, indicating that the low calcium response of all the mutants were normal. The ratios of YpCD1.08, YpCD1.09, YpCD1.16 gene transcriptional level at 37 °C and 26 °C were 2.3 ± 0.3, 2.3 ± 0.5 and 3.2 ± 0.7, respectively, indicating that these genes were transcribed in Yersinia pestis and their transcription regulations showed a temperature-dependence that was consistent with the well established temperature-dependent expression of Yersinia T3SS genes. The β-lactamases reporter assays demonstrated that ΔYpCD1.08 could translocate much higher level of YopE into HeLa cells, since that the light intensity ratio of 477/520 nm at 140 min was 2.5, whereas it was 1.8 for the wild-type strain, and the values in ΔYpCD1.09 and ΔYpCD1.16 were similar to the wild-type strain.

CONCLUSIONYpCD1.08, YpCD1.09, YpCD1.16 gene are likely to be the new members of T3SS, and the putative protein YpCD1.08 could play some roles in YopE secretion and translocation.

Bacterial Outer Membrane Proteins ; secretion ; Bacterial Secretion Systems ; genetics ; Genes, Bacterial ; Plasmids ; Protein Interaction Mapping ; Yersinia pestis ; genetics ; metabolism ; pathogenicity

OBJECTIVETo determine expression changes of major outer membrane protein(OMP) antigens of Leptospira interrogans serogroup Icterohaemorrhagiae serovar Lai strain Lai during infection of human macrophages and its mechanism.

METHODSOmpR encoding genes and OmpR-related histidine kinase (HK) encoding gene of L.interrogans strain Lai and their functional domains were predicted using bioinformatics technique. mRNA level changes of the leptospiral major OMP-encoding genes before and after infection of human THP-1 macrophages were detected by real-time fluorescence quantitative RT-PCR. Effects of the OmpR-encoding genes and HK-encoding gene on the expression of leptospiral OMPs during infection were determined by HK-peptide antiserum block assay and closantel inhibitive assays.

RESULTSThe bioinformatics analysis indicated that LB015 and LB333 were referred to OmpR-encoding genes of the spirochete, while LB014 might act as a OmpR-related HK-encoding gene. After the spirochete infecting THP-1 cells, mRNA levels of leptospiral lipL21, lipL32 and lipL41 genes were rapidly and persistently down-regulated (P <0.01), whereas mRNA levels of leptospiral groEL, mce, loa22 and ligB genes were rapidly but transiently up-regulated (P<0.01). The treatment with closantel and HK-peptide antiserum partly reversed the infection-based down-regulated mRNA levels of lipL21 and lipL48 genes (P <0.01). Moreover, closantel caused a decrease of the infection-based up-regulated mRNA levels of groEL, mce, loa22 and ligB genes (P <0.01).

CONCLUSIONExpression levels of L.interrogans strain Lai major OMP antigens present notable changes during infection of human macrophages. There is a group of OmpR-and HK-encoding genes which may play a major role in down-regulation of expression levels of partial OMP antigens during infection.

Antigens, Bacterial ; genetics ; metabolism ; Bacterial Outer Membrane Proteins ; genetics ; metabolism ; Cell Line ; Chaperonin 60 ; genetics ; metabolism ; Humans ; Leptospira interrogans ; genetics ; immunology ; pathogenicity ; Lipoproteins ; genetics ; metabolism ; Macrophages ; microbiology

This study was aimed to construct a prokaryotic expressing vector of Hap gene from Nontypeable Haemophilus influenzae, and express and identify the fusion proteins of Hap-His in E. coli. The gene encoding protein Hap was amplified from Nontypeable Haemophilus influenzae ATCC49247 chromosomal DNA by PCR, then it was cloned into prokaryotic expression plasmid pET-32a (+). The recombinant plasmid pET-32a(+)-Hap was transformed into E. coli BL21 and expression was induced by Isopropy-beta-D-thiogalatoside(IPTG). The Hap-His fusion protein expressed so was analyzed by SDS-PAGE and Western-blot. The results showed that the recombinant expressive plasmid pET-32a (+)-Hap was constructed successfully, and the recombinant plasmid expressed Hap-His fusion protein with relative molecule mass 176 000 and mainly existed in inclusion body. This fusion protein could combine with anti-His monoclonal antibody specifically through Western blot analysis. Successful expression of Hap-His fusion protein in prokaryotic cell could lay a basis for further study of immunocompetence of Hap protein and development of NTHi vaccine.
Bacterial Outer Membrane Proteins ; biosynthesis ; genetics ; Cloning, Molecular ; Escherichia coli ; genetics ; metabolism ; Genetic Vectors ; genetics ; Haemophilus influenzae ; genetics ; Recombinant Fusion Proteins ; biosynthesis ; genetics ; Serine Endopeptidases ; biosynthesis ; genetics

OBJECTIVETo construct prokaryotic expression systems of ltB/ctB-ompL1/1 fusion genes and to determine the L.interrogans carrying status in leptospirosis patients with the expression products.

METHODSThe fusion genes ltB-ompL1/1 and ctB-ompL1/1 were constructed using linking primer PCR method. SDS-PAGE was used to examine expression of the target recombinant proteins rLTB-rOmpL1/1 and rCTB-rOmpL1/1. Western blot and GM1-ELISA were used to measure the immunogenic and GM(1)-binding activities of rLTB-rOmpL1/1 and rCTB-rOmpL1/1, respectively. PCR and MAT were performed to detect the expression of ompL1 gene in 97 wild L.interrogans strains. Antibodies against ompL1 gene products in serum samples of 228 leptospirosis patients were detected with ELISA method.

RESULTSThe homogeneity of nucleotide and putative amino acid sequence of ltB-jompL1/1 and ctB-ompL1/1 fusion genes were 99.7 % - 99.9 % and 99.5 % - 100 %, in comparison with the reported corresponding sequences. Expression outputs of both rLTB-rOmpL1/1 and rCTB-rOmpL1/1, mainly present in inclusion body, accounted for 10% of the total bacterial protein. Both rLTB-rOmpL1/1 and rCTB-rOmpL1/1 could combine to rabbit anti-rOmpL1/1 serum and bovine GM(1). 89.7 % of L.interrogans wild strains had ompL1 gene. 87.6% of the wild L.interrogans strains presented positive results for MAT (titers :1:4-1:256) with the rabbit anti-rOmpL1/1 or anti-rOmpL1/2 sera. 86.8% and 88.6% of the patients' serum samples were positive for rOmpL1/1 and rOmpL1/2 antibodies, respectively.

CONCLUSIONThe fusion proteins, rLTB-rOmpL1/1 and rCTB-rOmpL1/1, showed high immunogenic and GM(1)-binding activities. ompL1 gene is extensively distributed and frequently expressed in different serogroups of L.interrogans and its products expressed by different genotypes exhibit extensive cross-antigenicity.

Bacterial Outer Membrane Proteins ; genetics ; immunology ; Bacterial Toxins ; genetics ; Bacterial Vaccines ; genetics ; Cloning, Molecular ; Enterotoxins ; genetics ; Escherichia coli Proteins ; genetics ; Genes, Bacterial ; genetics ; Humans ; Leptospira interrogans ; genetics ; immunology ; Prokaryotic Cells ; metabolism ; Recombinant Fusion Proteins ; genetics ; immunology ; Vaccines, Synthetic ; genetics

OBJECTIVETo construct a fused expression vector of the outer membrane protein gene PorB of Neisseria gonorrhoeae, express the fusion protein in the prokaryotic system, and obtain a gene recombination protein, for the purpose of preparing the ground for further research on the pathopoiesis and immune protective response of PorB.

METHODSA pair of primers were designed according to the known sequence of the PorB gene, and the PorB gene was amplified by PCR from the genome of Neisseria gonorrhoeae 29403 and cloned into the prokaryotic expression plasmid pGEX-4T-1 to generate pGEX-4T-PorB recombinants. The recombinant plasmid pGEX4T-PorB was transferred into competent cells E. coli BL21. After confirmed by restriction endonuclease digestion, PCR and DNA sequencing analysis, the recombinant protein was induced to express by isopropyl-beta-D-thiogalactoside (IPTG), and examined by SDS-PAGE and Western blotting.

RESULTSRestriction endonuclease digestion, PCR amplification and DNA sequencing analysis showed that the PorB gene of 1 047 bp was amplified from Neisseria gonorrhoeae DNA, and the recombinant plasmid pGEX-4T-PorB was successfully constructed and highly expressed in E. coli.

CONCLUSIONThe prokaryotic expression vector of pGEX-4T-PorB was successfully constructed and efficiently expressed in the prokaryotic system, which has provided a basis for further study on the biological activity of the PorB protein, as well as animal immune experiment and detection of Neisseria gonorrhoeae, and its application as a mucosal immune vaccine.

Bacterial Outer Membrane Proteins ; genetics ; metabolism ; Cloning, Molecular ; Escherichia coli ; metabolism ; Gene Expression ; Genetic Vectors ; Molecular Sequence Data ; Neisseria gonorrhoeae ; genetics ; metabolism ; Plasmids ; Porins ; genetics ; metabolism

Bacterial Outer Membrane Proteins ; chemistry ; genetics ; metabolism ; Escherichia coli Proteins ; chemistry ; genetics ; metabolism ; Glutamic Acid ; genetics ; metabolism ; Histidine ; genetics ; Hydrogen-Ion Concentration ; Ion Channel Gating ; genetics ; Lipid Bilayers ; metabolism ; Mutant Proteins ; chemistry ; genetics ; metabolism ; Mutation ; Porins ; chemistry ; genetics ; metabolism

To study the resistant mechanism and clinical significance of pseudomonas aeruginosa to beta-lactam antibiotics, the outer membrane permeability rate of 30 P. aeruginosa strains to 5 beta-lactam antibiotics was measured and their production of beta-lactamase and the beta-lactamase genes they carried detected. Furthermore, the relationship between the permeability, beta-lactamase and the clinical effects of beta-lactam antibiotics was observed. By using 14C-penicillin and liquid-scintillant isotope assay, the affinity of penicillin binding proteins (PBPS) was measured and their roles in the resistant mechanism studied. It was revealed that the permeability rate was higher in sensitive strains than in resistant ones (P < 0.05). All strains harbored 1-4 beta-lactamase genes and produced beta-lactamase. Higher permeability rate and higher degree of stability to beta-lactamase indicated better clinical therapeutic effects. The affinity of PBPs changed little without regard to the permeability and beta-lactamase. These results suggested that the permeability of outer membrane and beta-lactamase, but not PBPs, played important roles in the resistant mechanism of P. aeruginosa to beta-lactam antibiotics and affected the clinical therapeutic effectiveness of some patients.
Anti-Bacterial Agents ; pharmacology ; Bacterial Outer Membrane Proteins ; metabolism ; Humans ; Microbial Sensitivity Tests ; Permeability ; Pseudomonas aeruginosa ; drug effects ; beta-Lactam Resistance ; genetics ; beta-Lactamases ; metabolism ; beta-Lactams ; pharmacology

To study the resistant mechanism and clinical significance of pseudomonas aeruginosa to beta-lactam antibiotics, the outer membrane permeability rate of 30 P. aeruginosa strains to 5 beta-lactam antibiotics was measured and their production of beta-lactamase and the beta-lactamase genes they carried detected. Furthermore, the relationship between the permeability, beta-lactamase and the clinical effects of beta-lactam antibiotics was observed. By using 14C-penicillin and liquid-scintillant isotope assay, the affinity of penicillin binding proteins (PBPS) was measured and their roles in the resistant mechanism studied. It was revealed that the permeability rate was higher in sensitive strains than in resistant ones (P < 0.05). All strains harbored 1-4 beta-lactamase genes and produced beta-lactamase. Higher permeability rate and higher degree of stability to beta-lactamase indicated better clinical therapeutic effects. The affinity of PBPs changed little without regard to the permeability and beta-lactamase. These results suggested that the permeability of outer membrane and beta-lactamase, but not PBPs, played important roles in the resistant mechanism of P. aeruginosa to beta-lactam antibiotics and affected the clinical therapeutic effectiveness of some patients.
Anti-Bacterial Agents/*pharmacology ; Bacterial Outer Membrane Proteins/metabolism ; Microbial Sensitivity Tests ; Permeability ; Pseudomonas aeruginosa/*drug effects ; beta-Lactam Resistance/*genetics ; beta-Lactamases/metabolism ; beta-Lactams/*pharmacology

OBJECTIVETo construct a lipL32/1-lipL21-OmpL1/2 fusion gene and its prokaryotic expression system, and to establish an enzyme-linked immunosorbent assay (ELISA) using the rLipL32/1-LipL21-OmpL1/2 fusion antigen of Leptospira interrogans for sensitive and specific detection of IgM in the serum of patients with leptospirosis.

METHODSlipL32/1-lipL21-OmpL1/2 fusion genes were constructed using a primer-linking PCR. The target recombinant protein antigens, rLipL32/1, rLipL21, rOmpL1/2 and rLipL32/1-LipL21-OmpL1/2, were expressed and the purified antigens were then immobilized to the surface of microplate wells for ELISA-based detection of IgM in the sera of leptospirosis patients.

RESULTSOf 493 acute leptospirosis patients, 95.7% and 97.8% were positive by rLipL32/1-LipL21- OmpL1/2-IgM-ELISA using different serum dilutions, which was higher than the rLipL32/1-IgM-ELISA (93.1% and 90.3%), rLipL21-IgM-ELISA (90.3% and 87.0%), and rOmpL1-IgM-ELISA (85.6% and 81.1%) (P<0.01). All IgM-ELISAs tested negative against 56 non-leptospirosis patients with typhoid fever, hemorrhagic fever or dengue fever.

CONCLUSIONTrigeminal fusion antigen increases ELISA sensitivity and the rLipL32/1-LipL21-OmpL1/2- IgM-ELISA is a sensitive and specific serological diagnostic method for clinical leptospirosis.

Antigens, Bacterial ; genetics ; metabolism ; Bacterial Outer Membrane Proteins ; genetics ; metabolism ; Enzyme-Linked Immunosorbent Assay ; methods ; Humans ; Immunoglobulin M ; immunology ; Leptospirosis ; diagnosis ; metabolism ; Lipoproteins ; genetics ; metabolism ; Recombinant Fusion Proteins ; genetics ; metabolism

OBJECTIVETo construct lipL32/1-lipL21-OmpL1/2 fusion gene of Leptospira interrogans and its prokaryotic expression system, and to identify the immunogenicity of its products.

METHODSPCR using linking primers was applied to construct lipL32/1-lipL21-OmpL1/2 fusion gene and a prokaryotic expression system of the fusion gene was then established using routine genetic engineering technique. SDS-PAGE was used to examine output of the target recombinant protein rLipL32/1-LipL21-OmpL1/2. Double immunodiffusion and Western Blot assay were applied to identify immunogenicity of rLipL32/1-LipL21-OmpL1/2.

RESULTlipL32/1-lipL21-OmpL1/2 fusion gene with correct sequence and its prokaryotic expression system E.coli BL21DE3pET42a-lipL32/1-lipL21-ompL1/2 was obtained in this study. The output of rLipL32/1-LipL21- OmpL1/2 after optimisation was 37.78 mg/L. The immunodiffusion titer of rabbit antiserum against rLipL32/1-LipL21-OmpL1/2 was 1:4. The rLipL32/1-LipL21-OmpL1/2 antiserum was able to recognize rLipL32/1-LipL21-OmpL1/2, rLipL32/1, rLipL21 and rOmpL1/2. Positive Western hybridization signals were found among rLipL32/1-LipL21-OmpL1/2 and rabbit antiserum against whole cell of strain 56601 and serum from patients infected with L.interrogans serogroups Icterohaemorrhagiae, Grippotyphosa, Autumnalis and Pomona.

CONCLUSIONThe fusion gene lipL32/1-lipL21-OmpL1/2 and its prokaryotic expression system were successfully constructed in this study. The expressed fusion protein can be used as the antigen for developing universal genetic engineering vaccine and universal serological tests of leptospirosis.

Animals ; Antigens, Bacterial ; biosynthesis ; genetics ; Bacterial Outer Membrane Proteins ; biosynthesis ; genetics ; Bacterial Vaccines ; immunology ; Escherichia coli ; genetics ; metabolism ; Humans ; Leptospira interrogans ; genetics ; immunology ; Lipoproteins ; biosynthesis ; genetics ; Rabbits ; Recombinant Fusion Proteins ; biosynthesis ; genetics ; immunology ; Vaccines, Synthetic ; immunology