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ABSTRACT Background: Helicobacter pylori is an etiologic agent of gastroduodenal diseases. The microorganism, considered a type I carcinogen, affects about 50% of the global population. H. pylori virulence factors are determinant for the clinical outcome of the infection. The outer inflammatory protein A (oipA) gene encodes an outer membrane adhesin and is related to severe gastropathies, such as gastric cancer. Objective: The aim of this study was to evaluate the association of the oipA gene with the severity of gastroduodenal diseases in dyspeptic patients in region Central Brazil. Methods: The polymerase chain reaction (PCR) was used to determine the presence of H. pylori. Samples positives were used for molecular screening of the oipA gene. Gastropathies were categorized as non-severe and severe diseases. Results: Approximately 68% of patients had H. pylori and 36% were infected with H. pylori oipA+ strains. Infection was significantly associated in patients aged over 44 years (P=0.004). However, there was no association between oipA and patients' age (P=0.89). Approximately 46% of patients infected with oipA+ strains had some severe illness. Gastric adenocarcinoma was the most frequent severe gastropathy. The H. pylori oipA genotype was inversely associated with the severity of gastroduodenal diseases (OR=0.247, 95%CI: 0.0804-0.7149 and P=0.007). Conclusion: The characterization of possible molecular markers will contribute to personalized medicine, impacting the prognosis of patients.
RESUMO Contexto: Helicobacter pylori é um agente etiológico de doenças gastroduodenais. O microrganismo, considerado cancerígeno tipo I, afeta cerca de 50% da população mundial. Os fatores de virulência do H. pylori são determinantes para o desfecho clínico da infecção. O gene da proteína inflamatória externa A (oipA) codifica uma adesina da membrana externa e está relacionado a gastropatias severas, como o câncer gástrico. Objetivo: O objetivo deste estudo foi avaliar a associação do gene oipA com a gravidade das doenças gastroduodenais em pacientes dispépticos na região Brasil Central. Métodos: A reação em cadeia da polimerase (PCR) foi utilizada para determinar a presença de H. pylori. Amostras positivas foram utilizadas para triagem molecular do gene oipA. As gastropatias foram categorizadas como doenças não severas e severas. Resultados: Aproximadamente 68% dos pacientes apresentaram H. pylori e 36% estavam infectados com cepas H. pylori oipA+. A infecção foi significativamente associada em pacientes com idade superior a 44 anos (P=0,004). No entanto, não houve associação entre oipA e a idade dos pacientes (P=0,89). Aproximadamente 46% dos pacientes infectados com cepas oipA+ tiveram alguma doença severa. O adenocarcinoma gástrico foi a gastropatia severa mais frequente. O genótipo oipA de H. pylori foi inversamente associado à gravidade das doenças gastroduodenais (OR=0,247, IC95%: 0,0804-0,7149 P=0,007). Conclusão: A caracterização de possíveis marcadores moleculares contribuirá para a medicina personalizada, impactando no prognóstico dos pacientes.
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PURPOSE: Porphyromonas gingivalis and Tannerella forsythia have been implicated as the major etiologic agents of periodontal disease. These two bacteria are frequently isolated together from the periodontal lesion, and it has been suggested that their interaction may increase each one's virulence potential. The purpose of this study was to identify proteins on the surface of these organisms that are involved in interbacterial binding. METHODS: Biotin labeling of surface proteins of P. gingivalis and T. forsythia and liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis was performed to identify surface proteins involved in the coaggregating activity between P. gingivalis and T. forsythia. RESULTS: It was found that three major T. forsythia proteins sized 161, 100, and 62 kDa were involved in binding to P. gingivalis, and P. gingivalis proteins sized 35, 32, and 26 kDa were involved in binding to T. forsythia cells. CONCLUSIONS: LC-MS/MS analysis identified one T. forsythia surface protein (TonB-linked outer membrane protein) involved in interbacterial binding to P. gingivalis. However, the nature of other T. forsythia and P. gingivalis surface proteins identified by biotin labeling could not be determined. Further analysis of these proteins will help elucidate the molecular mechanisms that mediate coaggregation between P. gingivalis and T. forsythia.
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Bacteria , Bacterial Outer Membrane Proteins , Biotin , Biotinylation , Forsythia , Mass Spectrometry , Membrane Proteins , Membranes , Periodontal Diseases , Periodontitis , Porphyromonas gingivalis , Porphyromonas , VirulenceABSTRACT
Objective To clone and express the polymorphic membrane protein I(PmpI)gene of Chlamydia trachomatis(Ct), and to assess the immunogenicity and biological characteristics of PmpI. Methods A bioinformatic software was used to analyze the sequence of the PmpI gene of Ct, and to predict B cell epitopes in PmpI. With Ct serovar D DNA as the template, PCR was performed to amplify the N?terminal region(from position 90 to 1464)of the PmpI gene, which was cloned into a prokaryotic expression vector pET28a to express the recombinant protein PmpI. A Ni?ion affinity chromatography column was used to purify the recombinant protein, which was used to immunize New Zealand rabbits for preparation of polyclonal antibodies. Western blot analysis was conducted to evaluate the immunogenicity of this protein. Results A comprehensive analysis was carried out on the secondary structure, flexible regions, hydrophilicity plot, antigenic index and surface probability plot of the protein, which suggested that PmpI had 8 dominant B?cell epitopes. The product of PCR targeting the PmpI gene of Ct serovar D showed a total length of 1 375 bp. The recombinant prokaryotic expression vector pET28a?PmpI was successfully constructed. A recombi?nant protein with a relative molecular mass of approximately 50 000 was successfully expressed after isopropylβ?d?1?thiogalactopyranoside (IPTG) induction, and purified by affinity chromatography. Polyclonal antibodies against the recombinant protein were successfully prepared. Conclusion The N?PmpI protein of Ct serovar D is cloned and expressed successfully, laying a foundation for further studies on its biological functions.
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Objective To compare the toxicity of outer membrane vesicles ( OMVs) secreted by Acinetobacter baumannii strains with different drug-resistance spectrums.Methods Four Acinetobacter baumannii strains with different drug-resistance spectrums were collected (strain 33, 3237, B29 and 10), and OMVs produced by these strains were extracted and purified.BCA assay was used to determine the protein concentrations, and RAW264.7 cells were incubated with different concentrations of OMVs for 24 h. Cell viability was measured with CCK-8 assay, and gene expression of tumor necrosis factor-alpha ( TNF-α) , interleukin-6 ( IL-6) , interleukin-1 beta ( IL-1β) , keratinocyte-derived chemokine ( KC) and macrophage inflammatory protein 2 (MIP-2) was assessed by quantitative real-time PCR.One-way ANOVA was used for data analysis.Results According to the result of drug susceptibility test, strain 10 was extensively drug-resistant Acinetobacter baumannii ( XDRAB ) strain, strain B29 was multi-drug resistance Acinetobacter baumannii (MDRAB) strain, while strain 33 and 3237 were non-MDRAB strains.After incubated with different concentrations of OMVs for 24 h, cell viability of RAW264.7 declined with the increase of OMVs concentrations.OMVs released from strain10, B29 and 3237 significantly lowered the cell viability at the concentration of 5 μg/mL, while the cytotoxicity of OMVs released from strain 33 was much weaker, and no remarkable decrease in cell viability was observed even at the concentration of 25 μg/mL.OMVs of all strains induced the release of TNF-α, IL-6, IL-1β, KC and MIP-2 in RAW264.7 cells, and the levels of theses cytokines were increased with the concentration of OMVs.Inflammatory response in cells incubated with OMVs from strain 33 was the weakest, while OMVs from strain 10 induced strongest inflammatory response.KC and MIP-2 levels were significantly higher in RAW264.7 cells incubated with OMVs from strain 10 with a concentration of 5 μg/mL than that incubated with OMVs from other strains ( F=19.094 and 19.032,P<0.05 or <0.01).Conclusions OMVs from Acinetobacter baumannii strains with different drug-resistance spectrums are of different toxicity.OMVs from XDRAB and MDRAB strains have higher toxicities and may induce stronger inflammatory response.
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[Objective] To observe the specific immune responses induced by the recombinant major outer membrane protein (rMOMP) vaccine against Chlamydia trachomatis E serotype in rhesus monkeys.[Methods] Six rhesus monkeys were equally divided into three groups:adjuvant and protein group vaccinated with purified rMOMP and Freund's adjuvants,adjuvant group immunized with Freund's adjuvants only,and control group immunized with phosphate buffer.All the rhesus monkeys were intramuscularly immunized in the triceps brachii for 3 times at a 2-week interval.Two weeks after the last vaccination,serum,vaginal wash and venous blood samples were collected from the rhesus monkeys,and lymphocytes were isolated from the blood samples.Enzyme linked immunosorbent assay (ELISA) was performed to determine the specific IgG antibody and interferon level in sera and secretory IgA (sIgA) level in wash samples,and methyl thiazolyl tetrazolium (MTT) assay to evaluate the proliferation of lymphocytes after stimulation with Chlaraydia trachomatis serotype E elementary bodies.Delayed hypersensitivity was observed in rhesus monkeys challenged by inactivated Chlamydia trachomatis serotype E elementary bodies.In vitro antibody neutralization assay was conducted with the serum from rhesus monkeys.Indirect immunofluorescenee was used to detect Chlamydia trachomatis in exfoliative vaginal cells from rhesus monkeys from week 1 to 10 after challenge with Chlamydia trachomatis.Data were statistically analyzed by using one-way analysis of variance and least significant difference (LSD) test with the SPSS 14.0 software.[Results] The adjuvant and protein group differed statistically from the adjuvant group and control group in the serum level of specific IgG antibody (1.718 ± 0.213 vs.0.841 ± 0.315 and 0.791 ±0.437,both P＜ 0.05),interferon ((1086 ± 121.730) ng/L vs.(409 + 53.440) ng/L and (162 ± 48.046) ng/L,both P＜ 0.05),lymphocyte proliferation index (7.012 ± 1.026 vs.4.473 ± 1.850 and 1A26 ± 1.104,both P＜0.01 ) and the diameter of nodus in delayed hypersensitivity assay ( ( 1 1 ± 2.134) mm vs.(3 ± 0.914) mm and 0,both P ＜ 0.01 ).After attack,the exfoliative cells kept positive for Chlamydia trachomatis in the adjuvant and protein group from week 1 to 5,and in the other 2 groups from week 1 to 10,but were negative in the adjuvant and protein group from week 6 to 10.[Conclusion] The rMOMP vaccine can induce a specific,protective,humoral and cellular immune response against Chlamydia tracbomatis in rhesus monkeys.
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Objective To investigate the binding protein of chlamydiaphage phiCPG1 capsid protein Vp1 on chlamydia trachomatis outer membrane.Methods The bacterium with recombinant plasmid Vp1/pet30a( + ) was induced.The expressed protein was purified by gel recycling.FarWestern blot was utilized to' investigate the binding protein of Vp1 on chlamydial outer membrane,including recombinant polymorphic outer membrane protein (rPmp) and major outer membrane protein (MOMP).Results The recombinant protein Vp1 was successfully expressed in E.coli.Monoclonal antibody against Vp1 was used as primary antibody in Western blot,and no specific band was present,which indicated that the monoclonal antibody did not specifically bind with any rPmp.Far-Western blot results showed that there was an obvious band for the rPmpI,but no specific band for other rPmp and MOMP,which suggested that Vp1 could specifically bind with rPmpI protein on the chlamydial outer membrane of serotype D.Conclusions There is a binding site of Vp1 on the chlamydia trachomatis outer membrane.Vp1 may play an important role in the interaction between the chlamydiaphage and the chlamydiae.
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Objective To investigate the drug resistance and its distribution induced by β-lactamases and class Ⅰ integrons with the deficiency of Omp genes in Enterobacter cloacaes.Methods Totally 112 strains of Enterobacter cloacaes were isolated during January 2008 and May 2011.The identification of strains was performed by using Vitek-2 Compact automatic system; and antibiotic susceptibility was determined by K-B method.Isolates of E.cloacae were screened for carbapenemases by modified Hodge test,improved three dimensional test and EDTA-meropenem synergy test.Genes encoding AmpC β-lactamase,metallo-β-1actamases (MBLs) and OXA-like β-1actamases were screened by multiple PCR.Single PCR was used to detect ISEcpl,OmpK35/36,NDM-1 and OXA-48.The variable regions of class Ⅰ integrons were amplified and sequenced.Results Among 112 isolates,6 (5.4％) demonstrated positive in the modified Hodge test and 14 ( 12.5％ ) were positive in the improved three-dimensional test.No carbapenemases gene was found.There were 29(25.9％ ) strains positive for ESBLs genes,ISEcpl was found in the upstream of all the CTX-M-type ESBLs; OXA-1 ESBLs were detected in 2 isolates.AmpC β-lactamase genes were positive in 45 (40.2％) strains,and 82.2％ (37/45) were MIR-3 type.Twenty two isolates carried class Ⅰ integrons,and four different cassettes arrangements were identified within 16 strains:9 isolates harbored aadB-aadA2 ( 1 000 bp),5 isolates with dfrAl5 (700 bp),2 isolates with aadAl ( 1 000 bp).One isolate harbored all the above gene cassettes.The deficiency of OmpK35/36 was found in all strains.Conclusion ESBL,AmpC β-lactamase and the deficiency of OmpK35/36 are correlated with the resistance to carbapenems in Enteobacter clocace,and class Ⅰ integrons may also partly account for the multidrug-resistance.
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Objective To express major outer membrane protein (MOMP) of Chlamydia trachomatis E and to prepare rabbit polyclonal antibody. Methods The recombinant plasmid MOMP/ pGEX6p-l prepared by our lab was introduced into E. coli. The protein was expressed and purified by gel recycling, then was injected into New Zealand rabbits to produce polyclonal antibodies. Enzyme linked immunosorbent assay (ELISA) was used to detect the titer of antibody. The antibody specificity was identified by Western blot and immunofluorescence. Results The fusion recombinant protein glutathione S-transferase (GST)-MOMP was successfully expressed in E. coli. The titer of antibody recombinant protein detected by Western blot and to the endogenous MOMP of Chlamydia trachomatis in vitro detected by immunofluorescence. Conclusions The recombinant MOMP is successfully expressed and the MOMP antibody with high titer and high specificity is obtained. which will be helpful for Chlamydia trachomatis detection and related clinical research.
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Objecfive To detect serum antibodies to Pmp in patients with urogenital Chlamydia trachomatis infection and to assess the relationship between Pmp and urogenital C.traehomatis infection.Methods Twenty healthy adults and 77 patients with urogenital C. trachomatis infection were recruited into this study.A 3-month foilow-up was carried out in 43 patients,who were classified into persistent infection group(n=19)and negative-conversion group(n=24).Western-blot was performed to detect serum antibodies to Pmp in all subjects.Results The positivity rate of anti-Pmp antibodies was 90.20% (71/77) in patients,significantly higher than that in the normal controls[20% (4/20),P<0.05].All the 9 types of anti-Pmp antibodies were detected in patients with a varying positivity rates,which were 61.04% (47/77),88.31% (68/77),63.63% (49/77),28.57% (22,77),63.63% (49/77),75.32% (58/77),62.34% (48/77),77.92% (60/77)and 70.13% (54/77) for antibodies against PmpA,PmpB,PmpC,PmpD,PmpE,PmpF,PmpG,PmpH and PmpI respectivelyThe prevalence was highest for anti-Pmp B antibodies and lowest for anti-Pmp D antibodies.There was no significant difference in the positivity rate of anti-Pmp antibodies between persistent infection group and negativeconversion group.Conclusions Anti-Pmp antibodies could be generated in patients infected with C. trachomatis.The immunogenicity of different Pmps is different,and the immunoprotective activity of Pmps is rather weak.Individual differences exist in serum anti-Pmp antibodies among patients.Nine types of Pmps are expressed in patients with urogenital C. trachomatis infection.
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Objective To clone, express and purify Chlamydia trachomatis polymorphic membrane protein (Pmp G), and to identify its immunogenicity. Methods The Pmp G gene of C. trachomatis serotype E was amplified by PCR, cloned into prokaryotic expression vector PET30a (+). The positive recombinant was transformed into the bacterium E coli (BL-21), identified by enzyme digestion, PCR amplification and gene sequencing. Then, it was induced to express followed by the identification of expression product with SDS-PAGE and Western blotting. The purified protein was used to immunize BALB/C mice to test its immunogenicity. Results PCR produced a 1092 bp-sized DNA fragment, which had a sequence consistent with that of PmpG gene of C. trachomatis E type in the GenBank database. The molecular weight of expression product was 55 kD, which was proved to be the expected size, and Western Blotting confirmed it to be the specific protein. Moreover, special antibodies to PmpG were induced to be generated by mice immunized with the purified protein. Conclusions The constructed prokaryotic expression vector for PmpG is expressed successfully in E. coli, and the expression product shows immunogenicity.
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Objective To profile the omp1 genotypes of Chlamydia trachomatis (Ct) in patients with nongonococcal urethritis (cervicitis) in Guangzhou region. Methods Swab samples were obtained from the urethra of males and cervix of females in clinical settings of venereology and gynecology as well as at outreach sites for the prevention and control of sexually transmitted diseases (STDs). DNA was extracted from the swabs and nested PCR was performed to amplify the variable domain (VD) 1 - 3 of omp1 gene of Ct followed by gene sequencing. The genotypes of Ct were determined based on the amino acid mutation in VD 1 - 2 of omp1 gene. Results Totally, 1208 swabs were collected. Of them, 132 were Ct positive, and 130 positive samples underwent genotyping. Ten ompl genotypes were determined in total, including serotype E (38, 29.23%), D (25, 19.23%), J(24, 18.46%), F(21, 16.15%), G(7, 5.38%), H(5, 3.85%), K(5, 3.85%), B(2, 1.54%), Ja (2, 1.54%), I (1, 0.77%). E, D, J and F were the dominant type of Ct in this region, and amounted to 83% of all the Ct isolates. Mutations were observed within VD 1 and 2 of omp1 gene in serotype D, B and K.Serotypes were undetermined for Ct in 2 patients with mixed infection. Conclusions In Guangzhou region, E,D, F and J are the predominant genotypes of Ct, and amount to 83% of all the Ct isolates. Ct serotype B is also observed in the urethra of males and cervix of females in this region.
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Objectives To analyze the characteristics of antigenic genes of clinical Bordetella pertussis strains recently isolated by analyzing the sequence of pertussis toxin S1 subunit(ptxS1) , pertactin (Prn) , fimbriae 2 (Fim2) and fimbriae 3 (Fim3 ) genes of four clinical isolates. Methods The 4 clinical isolates were collected in 2002 in Shijiazhuang of Hebei province. Four strains were isolated from pertussis patient's nasopharyngeal aspirate. ptxS1, Prn, Fim2 and Fim3 genes of these strains were amplified and sequenced. The sequences of those genes were compared with those of the isolates in GenBank and the isoaltes used in the production of pertussis vaccine in China. Results The results of the gene sequencing showed the four clinical isolates belonged to ptxS1 A type, which were different from those in vaccine strains. In addition, three Prn and three Fim'3 variants were observed in the four clinical isolates. Sequence analysis showed that the nucleotide sequence and deduced amino acid sequence of those strains had more than 99% identity with those in vaccine strains. The phylogenetic trees of those genes also showed these strains had a higher level of similarity with other Bordetella pertussis strains. Conclusion The four clinical isolates are different from vaccine strains in four antigenic genes, which laid a foundation for further studies on pertussis epidemiology,quality control and development of pertussis vaccine in China.
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Objective To investigate specific immune responses in mice induced by recombinant major outer membrane protein(rMOMP)of C.trachomatis serovaf E.Methods Thirty-six female BALB/cmice aged 3 to 4 weeks Were divided into three groups.i.e.,adjuvant group vaccinated、with purified rMOMP and Freund's adjutant,solitary group vaccinated with rMOMP only and control group vaccinated with phosphate buffered saline(PBS).All the mice were intramuscularly vaccinated on week 0,2 and 4.Blood samples and vaginal washes were obtained from these mice on week 6,then,mice were challenged with elementary body(EB)of C.trachomatis serovar E at the footpad followed by the observation of delayed hypersensitivity.On week 7.mice were genitally infected with C.trachomatis EB;one week later,blood samples and vaginal washes were obtained again;six weeks later,spleen lymphocytes were isolated from the mice and stimulated bv C.trachomatis or ConA followed by the detection of cell proliferation with MTT assay.In vitro neutralization assay was also performed.ELISA was used to determine the titers of Chlamydia-specific IgO antibody in sera and IgA antibody in vaginal washes,as well as the level of IFN-γ in culture supernatant of lymphocytes and sefa of mice.Vaginal swabs were collected after genital challenge and subjected to C.trachomatis culture.Results The absorbance at 405 ms of Chlamydia-specific IgG antibody and proliferation index of lymphocytes were 0.641±0.059 and 5.085±1.291.respectively,in mice immunized with rMOMP and Frennd's adjuvant.significantly higher than those in mice immunized with rMOMP only(0.424±0.015 and 3.123 ±0.840.both P<0.05).The thickness of right hind footpad increased by 0.324±0.054 mm and 0.272±0.064 mm,respectively,in solitary group and adjuvant group,respectively,with significant difference between the two groups(P<0.05).A significant increase was also observed in the adjuvant group compared with the control group in the above three parameters(all P<0.01).Conclusion The rMOMP of C.trachomatis could efficiently induce Chlamydia-specific humoml and cellular immune responses in mice.
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Helicobacter pylori is able to colonize the human stomach and dwell in the human stomach for decades or for whole lifetime. A number of potential virulence factors contribute to Helicobacter pylori to colonize this unusual niche. Motility is an essential colonization factor based on the fact that nonmotile variants of Helicobacter pylori can't infect gnotobiotic piglets. Motility is not a colonization factor based on rapid loss of motility of Helicobacter pylori in the gastric lumen in vivo. The exact roles of Helicobacter pylori motility are not yet known. The aim of this article is to discuss correlation between colonization and motility of Helicobacter pylori.
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Objective To express outer membrane protein 2(Omp2) of Chlamydia trachomatis, purify expressed products and study its immunity.Methods The target gene encoding Omp2 167—434 amino acid residues was amplified by PCR from C. trachomatis template DNA. The targeted DNA fragment was cloned into expression vector pET28b(+) and introduced into competent E. coli BL21(DE3) cell. Recombinant Omp2aa_ 167 ～aa_ 434 was expressed after induction by IPTG and analyzed by SDS-PAGE and Western blot, purified with Ni-NTA-His affinity chromatography. The rOmp2aa_ 167 ～aa_ 434 was used to immune rabbits for immunogenicity assessment.Results Restriction enzymes cleavage analysis and DNA sequencing confirmed that the plasmid pET28b(+)/Omp2aa_ 167 ～aa_ 434 was correctly constructed. The 35.0?103 molecular weight pure protein, which specifically reacted with serum from C. trachomatis infected patient by Western blot, was obtained by optimizing the conditions for both expression and purification. The titer of serum antibodies was above 1∶1 280 as detected by ELISA.Conclusion The expressed product showed good immunity.
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Objective To construct the recombinant plasmid containing the major outer membrane protein(MOMP) gene of Chlamydia trachomatis and expres s MOMP protein in E.coli BL21. Methods The MOMP gene was amplified by polymera se chain reaction from the genome of Chlamydia trachomatis serovar D. The amplif ied fragment was directly inserted into pUCm-T vector and verified by DNA sequen cing. MOMP gene was then subcloned into the prokaryotic expression vector pET-22 b(+). The recombinant protein of MOMP was purified by Ni-NTA affinity chromatogr aphy and identified by SDS-PAGE and Western blot. Results The MOMP gene, which is about 1 200 bp, was successfully amplified and cloned. The DNA sequence of t he cloned MOMP gene was the same as that published by the GenBank. SDS-PAGE anal ysis showed that the relative molecular weight of this fusion protein was about 47 kDa which was consistent with the theoretically predicted value, and the spec ificity of this recombinant protein was confirmed by Western blot. Conclusions The MOMP gene of Chlamydia trachomatis was successfully cloned and expressed in the prokaryotic expression system, which may lay the foundation for the developm ent of Chlamydia trachomatis vaccine.
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Objective To study the relation of the porin at the out membrane with resistance to cefoxitin in Enterobacter cloaceae. Methods The extended spectrum beta lactamase(ESBLs) was detected by phenotypic confirmatory test according to NCCLS M100 S9;the beta lactamase and out membrane protein(OMP) was extracted by ultrasonication,the beta lactamase was detected by ultraviolet spectrophotometer,the composition of OMP was analyze by SDS PAGE. Results The 6 strains in 9 strains of Enterobacter cloaceae with resistance to cefoxitin lost 18 kda protein band and did not product hydrolase to cefoxitin and 5 strains was ESBLs positive. 2 strains producing hydrolase to cefoxitin did not lose the 18 kda protein. One strain with resistance to cefoxitin was producing ESBLs but did not defect the 18kda protein band and product hydrolase to cefoxitin. Conclusion The defect of the 18 kda protein band is nearly relation with resistance to cefoxitine in Enterobacter cloaceae.
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Objective To study the mutations of Pseudomonas aeruginosa oprD gene in Imipenem-resistant clinical isolates. Methods Random amplified polymorphic DNA typing(RAPD) was carried out to analyse the homology in 10 Imipenem-resistant clinical isolates. Pseudomonas aeruginosa oprD gene in 10 Imipenem-resistant clinical isolates were amplified by polymerase chain reaction and sequenced. Results Ten Imipenem-resistant clinical isolates were divided into four different clones which can not produce metallo ?-lactamase. As compared with sequence X63152, oprD gene of Pseudomonas aeruginosa varied greatly. The aberration rates exceed 50%. There were multiple point mutations within 276～387 bp coding region of 30, 11, 9, 20, 31 strains. Due to the mutations of 308 bp G→C and 344 bp C→A, threonine and diaminocaproic acid were replaced by serine and threonine respectively. The DNA deletion of 393～412 bp in oprD gene contributes to the frame shift mutation in the following nucleotide sequence. The deletion of 264～273 bp in the coding region of oprD gene in 13 and 21 clone strains leads to frame shift mutations forming terminal codon TAA(319～321 bp).Base substitutions and multiple point mutations were obvious in the coding regions of 1 and 22 clone strains. Their aberration rates were 54.03% and 74.89% respectively. Conclusions The mutations of Pseudomonas aeruginosa oprD gene in Imipenem-resistant clinical isolates are various.
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Objective To construct,express,purify and identify the gene encodi ng major outer membrane protein of Neisseria gonorrhoeae (Porin I, or PI). Metho ds The gene encoding for PI of N.gonorrhoeae was amplified by PCR and cloned int o expression plasmid pGEX-4T-2 to form pGEX-4T-2/PI recombinants. A high lev el expression of GST-PI fusion protein was obtained in GST gene fusion system (GST:glutathione S transferase). The analysis indicated that the expressed pr otein was present predominantly in the insoluble form. Therefore, the induced pr otein was purified by SDS-PAGE, and bands corresponding to polypeptides of GST-PI fusion protein were excised and subjected to electroelution. A dot immunoch romatographic assay was employed to demonstrate whether the purified protein was gonococcal PI specific. Results The pGEX-4T-2/PI expression recombinants were constructed,expressed,purified and identified successfully. SDS-PAGE analysis and dot immunochromatographic assay suggested that the recombinant GST-PI fusio n protein was a 60 000 molecular weight protein andidentical in size to native PI and reacted with anti-PI monoclonal antibody. Conclusion Our results may lead to a potentiality for further study of diagnosti c kits and vaccine for Neisseria gonorrhoeae.