Study on Outer Membrane Protein Patterns of Escherichia coli O38,O53 and O75 Isolated from Chickens

[Objective] This study aimed to investigate the outer membrane protein （OMP） patterns of Escherichia coli 038, 053 and 075 isolates from chickens. [Method] Eight pathogenic E. coil isolates with various serotypes were used as experimental materials to extract OMP by using supersonic schizolysis method and Sarcosyl. After SDS-PAGE electrophoresis, OMP patterns of the extracted products were determined based on the OMP model diagram. [Result] OMP of eight E. coil isolates with three serotypes were divided into three patterns, to be specific, 2 075 isolates respectively belonged to OMP-I and OMP-II pattern, 1 053 isolate belonged to OMP-II pattern, and 5 038 isolates belonged to OMP-I and OMP-III pattern. [Conclusion] Experimental results showed that E. coli isolates with the same serotype may belong to completely different OMP patterns, while serologically unrelated isolates may belong to the same OMP pattern. OMP of E. coil isolates with the same serotype may generate genetic differentiation; in addition, OMP of E. coli isolates with different serotypes may have different genetic correlation.

Prokaryotic Expression and Identification of Outer Membrane Protein 2 of Chlamydia trachomatis

Objective: To construct a recombinant plasmid containing the outer membrane protein 2 (Omp2) gene of Chlamydia trachomatis and express Omp2 in E.coli. Methods: The omp2 gene of C. trachomatis serovar D was cloned into pQE30 vector following PCR amplification from genomic DNA. E. coli M15 transformants were induced to express the fusion protein by IPTG and the product was identified by SDS-PAGE and Western blot. Results: Confirmed by enzyme cleavage analysis and DNA sequencing, a correct recombinant plasmid pQE30/omp2 was constructed. The fusion protein from the transformants was approximately 60 kDa in size in SDS-PAGE analysis, which could specially react with anti-6 X His mouse monoclonal IgG antibodies. Conclusion: We successfully expressed Omp2 in E. coli M15, providing an efficient and simple system for assaying the immunological properties of Omp2.

Development and Evaluation of a MAb-Based ELISA for Detection of Chlamy- dophila pneumoniae Infection with Variable Domain 2 and 3 of the Major Outer Membrane protein

Objective This paper aims to develop a monoclonal antibodies （MAbs）- based ELISA for detecting Chlamydophila pneumoniae （C. pneumonioe） antigens in humans with the variable domains （VD） 2 and 3 of the major outer membrane protein （MOMPvD2-VD~） and to assess its sensitivity and specificity by comparing with a widely used MAb that is able to recognize the elementary bodies of C. pneumoniae. Methods MOMPvo2-vo3were overexpressed in Escherichia coil and purified by affinity chromatography. Mice were immunized with the recombinant antigen, and hybridomas secreting MAbs were screened. Three stable hybridomas clones were selected and named 5D6, 7G3, and 8C9. The MAbs-based ELISA was scrutinized for species-specific recognition with a number of human throat swab samples from Group I （156 patients with typical respiratory illness clinically confirmed before） and Group II （57 healthy donors）. Results In Group I, 55 positive cases were detected by anti-EB MAb-based ELISA, 51 cases were positive by MAbs 5D6-based ELISA, and 33 and 38 cases were positive by MAb 8C9 and 7G3-based ELISA respectively. Of the 57 samples from Group II ＂healthy donors＂, 5 were positive and 52 were negative with both anti-EB and 5D6-based tests, while 2 and 3 positive cases were identified by the other two MAb-based ELISAs respectively. Conclusion The novel MOMPvD2.VD3 MAb-based assay may have higher specificity than the anti-EB MAb, which may possibly be used as an alternative tool for the diagnosis of C. pneumoniae infection.

Antimicrobial Susceptibility and Characterization of Outer Membrane Proteins of Aeromonas hydrophila Isolated in China

Aeromonas hydrophila isolates from clinical cases （n=43） were tested against 8 antimicrobial agents and typed by outer membrane protein （OMP） pattern by using sodium dodecyl sulfate gel electrophoresis. All isolates were resistant to ampicillin （MICs, ≥16 μg mL-1） and sulfamonomethoxine （MICs≥64 μg mLl）, but susceptible to norfloxacin （MICs,≤0.5 μg mL-1）. There was a high incidence of resistance to erythromycin （90.70%） and tylosin （93.02%）, while a low incidences of resistance to ciprofloxacin （2.33%）, enrofloxacin （2.33%） and florfenicol （4.65%）. Six different outer membrane protein patterns were found among 34 isolates by analyzing proteins in the range of 22 to 50 kDa, other than 9 isolates with their respective profiles. The strains with the similar OMP profiles had similar resistances. Compared with the other strains from the same OMP patterns, NB-1, A.Pun and MR-1 had lacked the proteins in the range of 30 to 45 kDa and their resistance to florfenicol substantially increased. It is speculated that the outer membrane protein changes might correlate with decreased susceptibility to florfenicol in the three strains. Some strains which showed completely identical OMP types had a little difference in their resistance to fluoroquinolones, indicating that there might be other factors that were involved in the antimicrobial resistance of A. hydrophila.

Determination of the genus-specific antigens in outer membrane proteins from the strains of Leptospira interrogans and Leptospira biflexa with different virulence

Objective:To determine the existence of genus-specific antigens in outer membrane proteins (OMPs) of leptospira with different virulence. Methods: Microscope agglutination test (MAT) was applied to detect the agglutination between commercial rabbit antiserum against leptospiral genus-specific TR/Patoc I antigen and 17 strains of Leptospira interrongans belonging to 15 serogroups and 2 strains of Leptospira biflexa belonging to 2 serogroups.The outer envelopes (OEs) of L.interrogans serogroup Icterohaemorrhagiae serovar lai strain lai (56601) with strong virulence and serogroup Pomona serovar pomona strain Luo (56608) with low virulence,and L.biflexa serogroup Semaranga serovar patoc strain Patoc I without virulence were prepared by using the method reported in Auran et al.(1972).OMPs in the OEs were obtained by treatment with sodium deoxycholate. SDS-PAGE and western blot were used for analyzing the features of the OMPs on electrophoretic pattern and the immunoreactivity to the antiserum against TR/Patoc I antigen, respectively. Results:All the tested strains belonging to different leptospiral serogroups agglutinated to the antiserum against leptospiral genus-specific TR/Patoc I antigen with agglutination titers ranging from 1:256-1:512. A similar SDS-PAGE pattern of the OMPs from the three strains of leptospira with different virulence was shown and the molecular weight of a major protein fragment in the OMPs was found to be approximately 60 KDa.A positive protein fragment with approximately 32 KDa confirmed by Western blot,was able to react with the antiserum against leptospiral genus-specific TR/Patoc I antigen, and was found in each the OMPs of the three stains of leptospira.Conclusion: There are genus-specific antigens on the surface of L.interrogans and L.biflexa. The OMP with molecular weight of 32 KDa may be one of the genus-specific protein antigens of leptospira.

Immunogenicity and protective role of antigenic regions from five outer membrane proteins of Flavobacterium columnare in grass carp Ctenopharyngodon idella

Flavobacterium columnare causes columnaris disease in freshwater fi sh. In the present study, the antigenic regions of fi ve outer membrane proteins(OMPs), including zinc metalloprotease, prolyl oligopeptidase, thermolysin, collagenase and chondroitin AC lyase, were bioinformatically analyzed, fused together, and then expressed as a recombinant fusion protein in Escherichia coli. The expressed protein of 95.6 k Da, as estimated by 10% sodium dodecyl sulfate-polyacrylamide gel electrophoresis, was consistent with the molecular weight deduced from the amino acid sequence. The purifi ed recombinant protein was used to vaccinate the grass carp, C tenopharyngodon idella. Following vaccination of the fi sh their Ig M antibody levels were examined, as was the expression of I g M, Ig D and Ig Z immunoglobulin genes and other genes such as MHC Iα and MHC I I β, which are also involved in adaptive immunity. Interleukin genes( IL), including I L- 1β, IL- 8 and I L- 10, and type I and type II interferon(I FN) genes were also examined. At 3 and 4 weeks post-vaccination(wpv), signifi cant increases in Ig M antibody levels were observed in the fi sh vaccinated with the recombinant fusion protein, and an increase in the expression levels of I g M, Ig D and Ig Z genes was also detected following the vaccinations, thus indicating that an adaptive immune response was induced by the vaccinations. Early increases in the expression levels of IL and IFN genes were also observed in the vaccinated fi sh. At four wpv, the fi sh were challenged with F. column a re, and the vaccinated fi sh showed a good level of protection against this pathogen, with 39% relative percent survival(RPS) compared with the control group. It can be concluded, therefore, that the fi ve OMPs, in the form of a recombinant fusion protein vaccine, induced an immune response in fi sh and protection against F. columnare.

Immunoproteomic Analysis of Bordetella bronchiseptica Outer Membrane Proteins and Identification of New Immunogenic Proteins

Bordetella bronchiseptica is a Gram-negative pathogen that causes acute and chronic respiratory infection in a variety of animals. To identify useful antigen candidates for diagnosis and subunit vaccine of B. bronchiseptica, immunoproteomic analysis was adopted to analyse outer membrane proteins of it. The outer membrane proteins extracted from B. bronchiseptica were separated by two-dimensional gel electrophoresis and analyzed by Western blotting for their reactivity with the convalescent serum against two strains. Immunogenic proteins were identified by matrix-assisted laser desorption/ionization time of flight-mass spectrometry（MALDI-TOF-MS）, a total of 14 proteins are common immunoreactive proteins, of which 1 was known antigen and 13 were novel immunogenic proteins for B. bronchiseptica. Putative lipoprotein gene was cloned and recombinantly expressed. The recombinant protein induced high titer antibody, but showed low protective indices against challenges with HB（B. bronchiseptica strain isolated from a infected rabbit）. The mortality of mice was 80% compared to 100% of positive controls. The identification of these novel antigenic proteins is an important resource for further development of a new diagnostic test and vaccine for B. bronchiseptica.

Gene cloning and prokaryotic expression of recombinant outer membrane protein from Vibrio parahaemolyticus

Gram-negative Vibrio parahaemolyticus is a common pathogen in humans and marine animals, The outer membrane protein of bacteria plays an important role in the infection and pathogenicity to the host. Thus, the outer membrane proteins are an ideal target for vaccines. We amplified a complete outer membrane protein gene （ompW） from E parahaemolyticus ATCC 17802. We then cloned and expressed the gene into Escherichia coli BL21 （DE3） cells. The gene coded for a protein that was 42.78 kDa. We purified the protein using Ni-NTA affinity chromatography and Anti-His antibody Western blotting, respectively. Our results provide a basis for future application of the OmpW protein as a vaccine candidate against infection by E parahaemolyticus. In addition, the purified OmpW protein can be used for further functional and structural studies.

Research progress on Helicobacter pyloriouter membrane protein

Helicobacter pylori (H pylori), one of the most common bacterial pathogens on human beings, colonizes the gastric mucosa. In its 95 paralogous gene families, there is a large outer membrane protein (OMP) family. It includes 32 members. These OMP are important for the diagnosis, protective immunity, pathogenicity of H pylori and so on. They are significantly associated with high H pylori density,the damage of gastric mucosa, high mucosal IL-8 levels and severe neutrophil infiltration. We introduce their research progress on pathogenicity.

Recombinant outer membrane protein F-B subunit of LT protein as a prophylactic measure against Pseudomonas aeruginosa burn infection in mice

AIM: To study immunogenicity of outer membrane protein F(Opr F) fused with B subunit of LT(LTB), against Pseudomonas aeruginosa(P. aeruginosa). METHODS: The Opr F, a major surface exposed outer membrane protein that is antigenically conserved in various strains of P. aeruginosa, is a promising immunogen against P. aeruginosa. In the present study recombinant Opr F and Opr F-LTB fusion gene was cloned, expressed and purified. BALB/c mice and rabbits were immunized using recombinant Opr F and Opr F-LTB and challenged at the burn site with P. aeruginosa lethal dose of 104 CFU. The protective efficacy of rabbit anti Opr F Ig G against P. aeruginosa burn infection was investigated by passive immunization. RESULTS: It has been well established that the LTB is a powerful immunomodulator with strong adjuvant activity. LTB as a bacterial adjuvant enhanced immunogenicity of Opr F and anti Opr F Ig G titer in serum was increased. Experimental findings showed significantly higher average survival rate in burned mice immunized with Opr F-LTB than immunized with Opr F or the control group. Rabbits anti Opr F Ig G brought about 75% survival of mice following challenge with P. aeruginosa. Post challenge hepatic and splenic tissues of mice group immunized with Opr F-LTB had significantly lower bacterial load than those immunized with Opr F or the control groups. CONCLUSION: These results demonstrate that LTBfused Opr F might be a potential candidate protein for a prophylactic measure against P. aeruginosa in burn infection.

30 and 32 kDa outer membrane proteins of Bordetella pertussis as a modulator on promoting degranulation of mast cells

The correlation between the activities of the outer menbrane proteins （OMPs） of Bordetella pertussis and the lgE-mediated asthma was investigated in the present study, in which the OMPs of B. pertussis and their components were prepared by detergent treatment and chromatography, and the molecular weights of the OMPs components were determined by SDS-PAGE. The amounts of total as well as the ovalbumin （OVA）-specific IgE induced by dead B. pertussis whole bacterial vaccine on guinea pigs were detected by ELISA. Meanwhile, the effect of the OMPs and their components to promote the degranulation of guinea pig mast cells was observed by using the mast cell degranulation test, and ELISA assay was used to measure the histatmine levels in the supematants from the mast cell cultures. Histamine sensitive test was used to demonstrate the effects of the OMPs and their components to increase the histamine lethal sensitivity in mice. It was found that four components with molecular weights of 30, 32, 38 and 69 kDa could be obtained from the OMPs of B. pertussts, and the dead whole bacteria vaccine of B. pertussis had the ability to increase the levels of the total as well as the OVA-specific IgE in sera of guinea pigs. The OMPs and their 30 and 32 kDa components demonstrated significantly enhancing effect on the degranulation of guinea pig mast cells, and the histamine levels in the supematants from the mast cell culture treated with OMPs and their 30 and 32 kDa components were also significantly increased. It is evident that the strong adjuvant activity and the enhancing effect to degranulation of mast cells and the release of histamine of certain outer membrane components of B. pertussis could be demonstrated as revealed by the results of the present study, suggesting the possibility of a close relationship between the infection of vaccination with B. pertussis and the IgE-mediated asthma.

SDS-PAGE analysis of whole cell protein and outer memrbane protein patterns of clinical isolates of Burkholderia pseudomallei

Objective:To investigate the banding patterns of whole cell protein(WCP) and outer membrane protein (OMP) of Burkholderia pseudomallei(B.pseudomallei) in clinical isolates from patients with melioidosis. Methods:WCP and OMP of of B.pseudomallei in 50 clinical isolates,from 47 patients with melioidosis were prepared and separated by polyacrylamide gel electrophoresis(SDS-PAGE) using 10%gels and stained with Coomassie brilliant blue.The banding patterns were compared by using a laser densitometer and dendrogram. Results:There were 6 different banding patterns of WCP and 2 types of OMP.Type 1 -5 WCP had 8 common protein bands at 19.0 - 45.0 kDa with identical OMP pattern.The banding patterns of WCP in type 6 were distinct from the others and also its OMP profile.The majority of clinical isolates(37/50,74%) were in type 1 WCP.Of the remaining isolates,8 were in type 2,2 in type 3,and one each was in type 4 to 6.There was no significant association between the WCP typing and the demographic or clinical features of the investigated patients.Conclusion:Despite the wide variation of clinical features of melioidosis,the results of this study show that B.pseudomallei had a few differences in the WCP and OMP profiles.Therefore typing of WCP and OMP,using SDS-PAGE analysis,could be an alternative method for phenotypic differentiation in clinical isolates of B.pseudomallei.

E型沙眼衣原体MOMP基因重组腺病毒的构建及免疫原性研究

目的:构建E型沙眼衣原体(Ct)主要外膜蛋白(MOMP)基因重组腺病毒,为沙眼衣原体腺病毒疫苗的研究奠定基础。方法:根据Genebank中E型Ct MOMP基因序列设计引物,用高保真PCR方法从E型Ct基因组DNA中扩增得到MOMP基因片段,克隆至pcDNAII载体,测序后连接入腺病毒穿梭载体pDC316。穿梭载体pDC316-MOMP与含腺病毒基因组的辅助质粒PBHGlox△E1,3Cre共转染至HEK293细胞,在Cre-loxP重组酶作用下进行重组,包装成重组腺病毒颗粒,用PCR和RT-PCR方法进行鉴定。并用动物免疫试验检测重组腺病毒的免疫原性。结果:从E型Ct基因组DNA中扩增出约1.1 kb的特异MOMP基因片段,酶切鉴定及DNA序列测定证实穿梭载体pDC316-MOMP构建正确。穿梭载体pDC316-MOMP与含腺病毒基因组的辅助质粒PBHGlox△E1,3Cre共转染至293细胞,出现明显细胞病变效应。收集重组腺病毒,PCR法证实重组腺病毒含有MOMP基因,RT-PCR证实重组腺病毒在293细胞能表达MOMP基因。重组腺病毒免疫小鼠可诱导特异性抗体产生,证明重组腺病毒具有良好免疫原性。结论:成功构建了E型沙眼衣原体MOMP基因重组腺病毒,该重组腺病毒可诱导小鼠产生特异性抗体。

沙眼衣原体D型MOMP基因的克隆和序列分析

目的 从D型沙眼衣原体培养物中克隆主要外膜蛋白(MOMP)基因。方法 利用细胞培养法扩增沙眼衣原体后,提取基因组为模板,经聚合酶链反应(PCR)扩增全长MOMP基因,并用酶切、PCR扩增及序列测定等方法对重组质粒进行鉴定。结果 成功扩增了MOMP基因,并插入克隆载体 pUCmT中。结论 MOMP基因的克隆为进一步开展沙眼衣原体的疫苗研究奠定了基础。

抗生素耐药性大肠杆菌外膜蛋白mOmpA N端序列分析

从抗生素耐药大肠杆菌中克隆了mOmpA(突变OmpA)并构建表达载体pET32a-mOmpA。序列比对分析表明,mOmpA N端与OmpA N端DNA序列同源性为79.93%,氨基酸同源性为81.17%。Swiss-Model蛋白结构预测表明,mOmpA loop环的方向发生了显著变化。研究结果有助于进一步了解大肠杆菌OmpA的结构和功能以及大肠杆菌耐药机制。

LTB-MOMP融合基因表达载体的构建及其在原核细胞中的表达

目的构建含大肠杆菌热不稳定肠毒素B亚单位(LTB)和鹦鹉热衣原体主要外膜蛋白(MOMP)融合基因(LTB-MOMP)的表达载体,并在原核细胞中表达融合蛋白。方法应用PCR从质粒EWD299和鹦鹉热衣原体中扩增LTB和MOMP基因,经与柔性肽连接后,插入pET-28a载体中,酶切鉴定正确后,转化大肠杆菌Rosetta,IPTG诱导表达,并纯化目的蛋白。SDS-PAGE和Westernblot分析外源蛋白的表达及表达产物的抗原特异性。结果重组工程菌可以表达相对分子质量约为54000的LTB-MOMP融合蛋白,表达量占菌体总蛋白的42%,LTB-MOMP融合蛋白具有良好的抗原特异性。结论已成功构建了LTB-MOMP融合基因表达载体,并在原核细胞中获得表达。

军团菌MOMPS基因的克隆并在原核系统中表达

以军团菌DNA为模板,PCR扩增获得军团菌主要外膜蛋白基因(M a jor ou ter m em brane prote in gene,om pS),与原核表达质粒pUC 18定向重组,构建重组质粒,转化大肠杆菌BL 21,并用限制性酶酶切分析、聚合酶链式反应、核酸序列分析、十二烷基磺酸钠-聚丙烯酰胺凝胶电泳、W estern印迹进行鉴定。实验结果表明我们扩增出了军团菌914 bp的om pS基因,成功构建了重组质粒pLPom pS,并在原核系统中得到了表达。

pEGFP/MOMP真核表达重组体的构建及表达

目的:克隆沙眼衣原体主要外膜蛋白(MOMP)基因,构建pEGFP/MOMP真核表达重组质粒,为沙眼衣原体核酸疫苗的研制提供依据。方法:用PCR方法从D型Ct基因组中扩增MOMP全基因片段,克隆入真核表达载体pEGFP相应的酶切位点中,阳性重组子经BamHI、KpnI双酶切、PCR扩增及测序鉴定;并经脂质体介导转染HeLa细胞,36h后观察瞬时表达情况。结果:PCR扩增得到约1.2kb的特异性MOMP基因片段;序列测定证实与GenBank登录的D型沙眼衣原体一致;筛选鉴定出真核表达重组体pEGFP/MOMP。结论:成功地构建了pEGFP/MOMP真核表达重组体,并在HeLa细胞中表达了MOMP。

抗沙眼衣原体主要外膜蛋白(MOMP)单克隆抗体的制备及初步应用

制备抗沙眼衣原体(CT)单克隆抗体,建立沙眼衣原体的胶体金免疫层析快速检测方法。采用纯化沙眼衣原体主要外膜蛋白(MOMP)免疫Balb/c小鼠,选取高效价的免疫小鼠脾细胞与骨髓瘤细胞融合,ELISA检测筛选分泌抗MOMP单克隆抗体(McAb)的细胞株并进行相关鉴定。共获得分泌IgG1,IgG2b和IgM的3株单克隆抗体杂交瘤细胞株。纯化的单克隆抗体与鹦鹉热衣原体、肺炎衣原体、肺炎支原体均无交叉反应。通过位点分析选择配对良好的两株McAb,制备检测CT的双抗体夹心法免疫层析试纸条。制备的胶体金试纸条对MOMP的最低检出值可达50 ng·mL-1。

嗜肺军团菌MOMP通过激活NOD2/RIP2信号通路抑制RAW264.7巨噬细胞的吞噬功能并增强其趋化能力

目的探讨嗜肺军团菌主要外膜蛋白(MOMP)对RAW264. 7巨噬细胞吞噬功能和趋化功能的影响并探讨其机制。方法采用MOMP与RAW264. 7巨噬细胞进行体外共培养,用CCK-8法检测MOMP对RAW264. 7巨噬细胞的毒性,确定半数抑制浓度(IC50)。采用(1. 14、0. 57、0. 28)μg/m L MOMP分别处理RAW264. 7巨噬细胞,并设细胞对照组。RAW264. 7巨噬细胞处理24、48、72 h,收集细胞和培养上清,用中性红吞噬实验检测巨噬细胞的吞噬功能;用TranswellTM小室检测巨噬细胞的趋化功能; ELISA检测细胞培养上清单核细胞趋化蛋白1(MCP-1)和白细胞介素10(IL-10)的含量;实时定量PCR检测巨噬细胞核苷酸结合寡聚结构域1(NOD1)、NOD2、受体相互作用蛋白2(RIP2) mRNA水平,Western blot法检测NOD1、NOD2、RIP2的蛋白水平。结果 CCK-8法检测MOMP对RAW264. 7巨噬细胞的IC_(50)为5. 69μg/m L;与对照细胞相比,MOMP处理引起RAW264. 7巨噬细胞吞噬功能降低且呈剂量和时间依赖性;随着MOMP剂量的增加,巨噬细胞的趋化能力及细胞培养上清中MCP-1、IL-10的分泌水平增加,并在36 h达到峰值; NOD2、RIP2的mRNA和蛋白表达水平也增加,NOD2和RIP2的mRNA水平在12 h达到高峰,蛋白水平在24 h达到峰值。结论 MOMP抑制RAW264. 7巨噬细胞的吞噬功能并增强其趋化功能,与激活NOD2/RIP2信号通路有关。