球形幽门螺杆菌致细胞空泡变性毒力研究

目的 揭示球菌幽门螺杆菌致细胞空泡变性毒力的变异情况。方法 采用延期培养和加亚抑菌浓度抗生素,对细胞毒相关蛋白基因阳性（ｃａｇＡ＾＋）,和细胞空泡毒素基因阳性（ｖａｃＡ＾＋）的高毒株幽门螺杆菌（Ｈｐ）进行球形诱变,进而检测该Ｈｐ至Ｈｅｌａ细胞空泡变性的毒力,并用ＳＤＳ－ＰＡＧＥ、ＰＣＲ及ＰＣＲ－ＳＳＣＰ技术,分析球形Ｈｐ蛋白产物及决定细胞空泡变性的ｃａｇＡ和ｖａｃＡ基因的变异情况。结果与结论 球形     

幽门螺杆菌flaA基因的变异

目的鞭毛是幽门螺杆菌（Ｈｐ）的重要侵袭因子,本研究拟检测Ｈｐ鞭毛素Ａ基因的变异性,进而研究其与Ｈｐ致病性的关系．方法我们对５２例胃粘膜活检标本和１８株Ｈｐ临床分离株进行Ｈｐ特异的１６ＳｒＲＮＡ基因和鞭毛素Ａ基因ＰＣＲ扩增和ＰＣＲＲＦＬＰ及ＰＣＲＲＦＬＰＳＳＣＰ分析．结果对４３例Ｈｐ（＋）的ｆｌａＡ基因ＰＣＲＲＦＬＰ（ＨｉｎｄⅢ）大约可分７个型（变异检出率为１６３％）,而ＰＣＲＲＦＬＰＳＳＣＰ可分３７个型（变异检出率为８６０％）,两者有非常显著性差异．结论ｆｌａＡ基因变异性极大,ＰＣＲＲＦＬＰＳＳＣＰ优于ＰＣＲＲＦＬＰ,是检测其变异的有效方法．     

幽门螺杆菌的cagA因子与胃癌的关系

幽门螺杆菌(Ｈｅｌｉｃｏｂａｃｔｅｒｐｙｌｏｒｉ,Ｈｐ)是慢性胃炎的重要病因,与消化性溃疡发生和复发密切相关,并与胃癌相关。1994年ＷＨＯ/ＩＡＲＣ会议将Ｈｐ确定为Ⅰ类致癌原[1],但Ｈｐ确切的致癌因子及致癌机制尚不明了。Ｈｐ的毒力因子我括运动力(鞭毛)、粘附力(粘附素)、尿素酶活性、脂多糖内毒素样活性物质、蛋白分解酶及磷脂酶Ａ等,这些毒力因子为所有的Ｈｐ具有。但另外两种毒力因子只存在于50%-60%的Ｈｐ中,所以越来越受人们的关注:它们是分子量为90ｋＤａ(Ｍｒ90000)的细胞空泡毒素(Ｖａｃｕｏｌａｔｉｎｇｃｙｔｏｔｏｘｉｎ…     

胃粘膜肠化中幽门螺杆菌感染与PCNA,c-erbB-2的表达

目的研究肠化胃粘膜幽门螺杆菌（Ｈｐ）阳性率与ＰＣＮＡ,ｃｅｒｂＢ２表达率之间关系,以探讨Ｈｐ感染在胃肠化发生、发展中作用．方法经病理检查证实的慢性胃炎伴肠化１１６例,对照组非溃疡性消化不良．应用改良ＷａｒｔｈｉｎＳｔａｒｙ法检测Ｈｐ,免疫酶组化ＳＰ法检测ＰＣＮＡ,ｃｅｒｂＢ２的表达,比较Ｈｐ阳性组和阴性组间ＰＣＮＡ,ｃｅｒｂＢ２的阳性表达率．结果胃粘膜肠化者Ｈｐ感染率增高（５８６％ｖｓ１８８％,χ２＝１０７９,Ｐ＜００１）,肠化胃上皮内少见Ｈｐ粘附,Ｈｐ阳性组ＰＣＮＡ,ｃｅｒｂＢ２表达高于阴性组（４８／６８ｖｓ１２／４８,χ２＝９０５,Ｐ＜００５;３６／７４ｖｓ２／４２,χ２＝１３２８,Ｐ＜００１）．结论Ｈｐ感染促进胃粘膜肠化,并使肠化胃粘膜细胞增殖迅速而启动恶性变,故Ｈｐ感染可能促进胃癌的形成．     

脂蛋白(a)对HepG2细胞纤溶酶原激活物抑制物-1分泌的影响

目的研究脂蛋白（ａ）是否能刺激肝细胞纤溶酶原激活物抑制物１（ＰＡＩ１）的分泌。方法将不同浓度的脂蛋白（ａ）加到培养的ＨｅｐＧ２细胞,应用酶联免疫吸附测定（ＥＬＩＳＡ）技术测定细胞上清液中的ＰＡＩ１抗原,采用逆转录多聚酶链式反应（ＲＴＰＣＲ）观测ＨｅｐＧ２细胞中ＰＡＩ１ｍＲＮＡ的表达。结果脂蛋白（ａ）能刺激ＨｅｐＧ２细胞ＰＡＩ１抗原的分泌并具剂量效应关系,同时ＰＡＩ１ｍＲＮＡ表达增加。结论脂蛋白（ａ）能刺激肝细胞ＰＡＩ１基因表达,脂蛋白（ａ）的这种作用可能参与了其致动脉粥样硬化的病理过程。     

乙型肝炎病毒C基因变屉对人白细胞抗原表达的影响

目的 阐明我国常见的ＨＢＶ／Ｃ变异对宿主细胞人类白细胞抗原（ｈｕｍａｎ ｌｅｕｋｏｃｙｔｅ ａｎｔｉｇｅｎ，ＨＬＡ）表达的影响。方法 构建携带野生型和变异型ＨＢＶ／Ｃ基因的真核细胞表达载体，转染ＨｅｐＧ２细胞，鉴定目的基因在宿主细胞中的表达，检测ＨＬＡ－１，ＨＬＡ－ＤＲ在宿主细胞膜上的表达。结果 ＰＣＲ和Ｗｃｓｔｅｒｎ ｂｌｏｔ分析能分别检测到目的ＤＮＡ片段和ＨＢｃＡｇ的表达，约１００％的ＨｅｐＧ     

PCR法诊断幽门螺杆菌感染的评价

目的系统评估聚合酶链反应扩增尿素酶Ａ基因（ＰＣＲ法）对幽门螺杆菌（Ｈｐ）感染的诊断价值．方法采用金标准及ＰＣＲ法检测６９例患者（慢性胃炎５２例、消化性溃疡１２例、胃癌５例）胃粘膜内Ｈｐ．结果金标准诊断有Ｈｐ感染３４例，ＰＣＲ法诊断３５例Ｈｐ阳性；金标准诊断３５例无Ｈｐ感染，ＰＣＲ法诊断３４例Ｈｐ阴性．故ＰＣＲ法敏感度为１００％，特异度为９７１％，粗一致性为９８５％，调整一致性为９８６％，误诊率（假阳性率）为２９％，漏诊率（假阴性率）为０，正确诊断指数（ｒ）为１０，阳性预测值（＋ＰＶ）为９７１％，阴性预测值（ＰＶ）为１００％，阳性似然比（ＬＲ＋）为３５，阴性似然比（ＬＲ）为０．结论ＰＣＲ法对胃粘膜Ｈｐ感染的诊断价值高于细菌培养、组织病理学，尿素酶试验各单项方法．     

PCR法检测胃粘膜中的幽门螺杆菌

目的建立检测幽门螺杆菌（Ｈｐ）的更为敏感的聚合酶链反应（ＰＣＲ），并探讨它在Ｈｐ感染的诊断及根除效果判定中的应用．方法以一对合成的与Ｈｐ１６ＳｒＲＮＡ基因互补的寡核苷酸为引物（ＣＰ１／ＣＰ２），建立了从胃粘膜中检测Ｈｐ的ＰＣＲ反应，并与常规检测方法进行比较．结果ＰＣＲ方法检测Ｈｐ标准菌株及５０株临床分离菌株均产生５００ｂｐ片段，检出的最小ＤＮＡ量为０１ｐｇ，相当于１００个细菌细胞；所有１３株其它细菌及无Ｈｐ感染的人胃粘膜则无扩增产物出现．用该方法检测９６名初诊患者Ｈｐ感染情况及２１名药物治疗后患者Ｈｐ根除情况，并与胃粘膜活组织尿素酶试验、细菌培养及银染色方法比较，证实ＰＣＲ方法可以检出常规方法不能检出的少量Ｈｐ．结论ＰＣＲ是检测Ｈｐ的最为敏感的方法，有助于Ｈｐ感染的诊断和Ｈｐ根除的精确判断     

PCR诊断幽门螺杆菌感染的临床价值

目的探讨ＰＣＲ法在诊断胃粘膜幽门螺杆菌（Ｈｐ）感染中的临床价值．方法用ＰＣＲ方法对１５４例胃病患者胃粘膜Ｈｐ尿酶基因ＤＮＡ片断进行扩增，同时与尿酶试验及血清ＨｐＩｇＧ测定方法进行比较．结果ＰＣＲＨｐＤＮＡ的阳性率达９１％，与尿素酶试验（７４％）及血清ＨｐＩｇＧ（８１％）测定相比有显著差异（Ｐ＜００５）．Ｈｐ感染率随受检者年龄增长而增高．Ｈｐ感染与胃窦（９３％）及胃体（８４％）腺癌关系密切，而与食管癌及贲门癌（８０％）关系不大．结论ＰＣＲ法可明显提高Ｈｐ诊断的敏感性和特异性，也为Ｈｐ感染的深入研究开拓了新的研究思路和手段     

人胃粘膜分离的幽门螺杆菌菌株的基因型和表现型

幽门螺杆菌（Ｈｐ）感染与慢性活动性胃炎、溃疡病、胃腺癌或ＭＡＬＴ淋巴瘤相关。Ｉ型Ｈｐ菌株具有空泡毒素（ＶａｃＡ）和细胞毒素相关抗原（ＣａｇＡ），可能与引起特殊的胃病有关。近年的兴趣之一是发现与Ｌｅｗｉｓ~ｂ血型抗原结合的Ｈｐ粘附蛋白一粘附素。表达粘附素的Ｈｐ菌株含有功能性ＢａｂＡ２基因，而另一些菌株中相应ＢａｂＡ１基因缺少一个开放读码框而不能翻译。作者研究了溃疡病（ｎ＝１３）、胃腺癌（ｎ＝１１）、ＭＡＬＴ淋巴瘤（ｎ＝１１）和胃窦炎（ｎ＝１８）患者的Ｈｐ００２分离株，对这些疾病与ＶａｃＡ、ＣａｇＡ…     

Virulence and potential pathogenicity of coccoid Helicobacter pylori induced by antibiotics

AIM: To explore the virulence and the potential pathogenicity of coccoid Helicobacter pylori (H. pylori) transformed from spiral form by exposure to antibiotic. METHODS: Three strains of H. pylori, isolated from gastric biopsy specimens of confirmed peptic ulcer, were converted from spiral into coccoid from by exposure to metronidazole. Both spiral and coccoid form of H. pylori were tested for the urease activity, the adherence to Hep-2 cells and the vacuolating cytotoxicity to Hela cells, and the differences of the protein were analysed by SDS-PAGE and Western blot. The mutation of the genes including ureA, ureB,hpaA, vacA and cagA, related with virulence, was detected by means of PCR and PCR-SSCP. RESULTS: In the coccoid H. pylori,the urease activity, the adherence to Hep-2 cells and the vacuolating cytotoxicity to Hela cells all decreased. In strain F44, the rate and index of adherence reduced from 70.0% +/- 5.3% to 33% +/- 5.1% and from 2.6 +/- 0.4 to 0.96 +/- 0.3 (P < 0.01), respectively. The invasion of coccoid H. pylori into Hep-2 cell could be seen under electronmicroscope. SDS-PAGE showed that the content of the protein with the molecular weight over Mr 74000 decreased, and the hybriditional signal in band M(r) 125000 weakened, while the band M(r)110000 and M(r)63000 strengthened in coccoid H.pylori as shown in Western blot. The results of PCR were all positive, and PCR-SSCP indicated that there may exist the point mutation in gene hpaA or vacA. CONCLUSION: The virulence and the proteins with molecular weight over M(r)74000 in coccoid H.pylori decrease, but no deletion exists in amplification fragments from ureA, ureB, hpaA, vacA and cagA genes, suggesting that coccoid H.pylori may have potential pathogenicity.     

Cloning and sequencing of cagA gene fragment of Helicobacter pylori with coccoid form

AIM: To clone and sequence the cagA gene fragment of Helicobacter pylori (H pylori) with coccoid form. METHODS: H pylori strain NCTC11637 were transformed to coccoid form by exposure to antibiotics in subinhibitory concentrations. The coccoid H pylori was collected. cagA gene of the coccoid H pylori strain was amplified by PCR. After purified, the target fragment was cloned into plasmid pMD-18T. The recombinant plasmid pMD-18T-cagA was transformed into E.coli JM109. Positive clones were screened and identified by PCR and digestion with restriction endonucleases. The sequence of inserted fragment was then analysed. RESULTS: cagA gene of 3,444 bp was obtained from the coccoid H pylori genome DNA. The recombinant plasmid pMD-18T-cagA was constructed, then it was digested by BamH I+Sac I, and the product of digestion was identical with the predicted one. Sequence analysis showed that the homology of coccoid and the reported original sequence H pylori was 99.7%. CONCLUSION: The recombinant plasmid containing cagA gene from coccoid H pylori has been constructed successfully. The coccoid H pylori contain completed cagA gene, which may be related to pathogenicity of them.     

Cloning and sequencing of cagA gene fragment of Helicobacter pylori with coccoid form

AIM:To clone and sequence the cagA gene fragment ofHelicobacter pylori(H pylon)with coccoid form.METHODS:Hpyloristrain NCTC11637 were transformedto coccoid form by exposure to antibiotics in subinhibitoryconcentrations.The coccoid Hpyloriwas collected,cagAgene of the coccoid Hpyloristrain was amplified by PCR.After purified,the target fragment was cloned into plasmidpMD-18T.The recombinant plasmid pMD-18T-cagA wastransformed into E.coli JM109.Positive clones were screenedand identified by PCR and digestion with restrictionendonucleases.The sequence of inserted fragment wasthen analysed.RESULTS:cagA gene of 3 444 bp was obtained from thecoccoid Hpylori genome DNA.The recombinant plasmidpMD-18T-cagA was constructed,then it was digested byBamH I Sac I,and the product of digestion was identicalwith the predicted one.Sequence analysis showed that thehomology of coccoid and the reported original sequenceH pylori was 99.7%.CONCLUSION:The recombinant plasmid containing cagAgene from coccoid H pylorihas been constructed successfully.The coccoid H pylori contain completed cagA gene,whichmay be related to pathogenicity of them.     

Virulence of water-induced coccoid Helicobacter pylori and its experimental infection in mice

AIM: To explore the virulence and the infectivity of coccoid Helicobacter ppylori(H.pylori) transformed from spiral form by exposure to sterile tap water.METHODS: Three strains of H.pylori, isolated from gastric biopsy specimens of confirmed peptic ulcer, were converted from spiral into coccoid form by exposure to sterile tap water.Both spiral and coccoid forms of H.pylori were tested for the urease activity, and the adherence to Hep-2 cells. The presence of flagella was examined under electron microscopy. In the experimental animal infection, the spiral and coccoid forms of H.pylori originated from the same strain F49 were inoculated intragastrically into BALB/c mice respectively four times at a 3-day interval. Half of the mice from each group were sacrificed at Day 21 and Day 28 after the last inoculation. Histology and H.pylori colonization were detected by urease test of gastric mucosa, cultures of H. pylori,and electron microscopy and so on.RESULTS: The urease activity and the ability of adherence to Hep-2 cells were found to be lower in coccoid H.pylori than that in its spiral form. For example, the transformation in strain F44 led to a significant decrease of the adherence rate and adherence index from 70.0±5.3 % to 30.2±3.5 %(P＜0.01), and from 2.6±0.4 to 0.86±0.3 (P＜0.01),respectively. The flagella of coccoid H.pylori were observed under electron microscope. In the experimental infection in mice, the positive rate of gastric mucosa urease test was 93.8 % (15/16) in the group infected by spiral H.pylori and 50 % (8/16) in the group infected by coccoid H. pylori,and the estimated coccoid H.pylori colony number was 1.75 vs0,56. The positive rates of H. pyloriculture were 87.5 %(14/16) in spiral H. pylori group and 68.8 % (11/16) in coccoid H.pylorigroup. There was no significant difference in either urease test or bacterial culture rate between the groups examined at Day 21 and Day 28 after inoculation. Electron microscopic examination of the samples taken from both groups showed the adherence of H. pylori in spiral,bacillary and coccoid shapes to the epithelial cells of gastric wall. Histological examination showed the occurrence of gastric mucosal injury as indicated by various degrees of erosion, ulcer, and inflammatory cell infiltration. Mucosal injury was slighter in the mice infected by coccoid H. pylori.No positive result was obtained in the control group that received intragastrical administration of sterile tap water.     

Use of different PCR primers and gastric biopsy tissue from CLO test for the detection of Helicobacter pylori

Four different DNA loci were assessed for the detection of H. pylori by PCR on gastric biopsy specimens. PCR, with a primer specific 860 bp DNA fragment, was the most sensitive, with a detection limit of 0.02 pg H. pylori DNA, corresponding to approximately 10 organisms. Nested-PCR of the 860-bp DNA fragment was 10-fold more sensitive than single-step PCR. The sensitivity and specificity of the four PCR methods, in comparison to the results obtained from histology and the urease test, are as follows: 80.7% and 76% for the hpaA gene; 100% and 76% for the 16S rRNA gene; 84.6% and 80.0% for the 860-bp DNA fragment; 61.5% and 84.0% for the ureC (glmM) gene, respectively. The sensitivity of nested-PCR for the 860-bp DNA fragment was 100%. This nested-PCR gave positive results for eight specimens which were negative by conventional methods. PCR can be performed on gastric biopsy specimens obtained from the CLO test.     

Construction of hpaA gene from a clinical isolate of Helicobacter pylori and identification of fusion protein

AIM: To clone hpaA gene from a clinical strain of Helicobacter pylori and to construct the expression vector of the gene and to identify immunity of the fusion protein. METHODS: The hpaA gene from a clinical isolate Y06 of H.pylori was amplified by high fidelity PCR. The nucleotide sequence of the target DNA amplification fragment was sequenced after T-A cloning. The recombinant expression vector inserted with hpaA gene was constructed. The expression of HpaA fusion protein in E.coli BL21DE3 induced by IPTG at different dosages was examined by SDS-PAGE. Western blot with commercial antibody against whole cell of H.pylori as well as immunodiffusion assay with self-prepared rabbit antiserum against HpaA fusion protein were applied to determine immunity of the fusion protein. ELISA was used to detect the antibody against HpaA in sera of 125 patients infected with H.pylori and to examine HpaA expression of 109 clinical isolates of H.pylori. RESULTS: In comparison with the reported corresponding sequences, the homologies of nucleotide and putative amino acid sequences of the cloned hpaA gene were from 94.25-97.32 % and 95.38-98.46 %, respectively. The output of HpaA fusion protein in its expression system of pET32a-hpaA-BL21DE3 was approximately 40 % of the total bacterial proteins. HpaA fusion protein was able to combine with the commercial antibody against whole cell of H.pylori and to induce rabbit producing specific antiserum with 1:4 immunodiffusion titer after the animal was immunized with the fusion protein. 81.6 % of the serum samples from 125 patients infected with H.pylori (102/125) were positive for HpaA antibody and all of the tested isolates of H.pylori (109/109) were detectable for HpaA. CONCLUSION: A prokaryotic expression system with high efficiency of H.pylori hpaA gene was successfully established. The HpaA expressing fusion protein showed satisfactory immunoreactivity and antigenicity. High frequencies of HpaA expression in different H.pylori clinical strains and specific antibody production in H.pylori infected patients indicate that HpaA is an excellent and ideal antigen for developing H.pylori vaccine.     

球形幽门螺杆菌致小鼠感染

目的 证明球形幽门螺杆菌体内致病性。方法 用抗生素和水诱导幽门螺杆菌（Hp）球变,螺旋形和球形Hp分别经胃灌注接种BALB／c小鼠,实验组小鼠（各16只）接种Hp菌液0.4ml/只（10^9/ml）,接种4次,2w完成,对照组（10只）接种生理盐水,距最后一次接种后3和4w分别处死小鼠各半,取胃粘膜组织作细菌学检测（包括胃粘膜快速尿素酶试验,细菌培养鉴定,电镜观察）和组织学检测。结果 螺旋菌、抗生素旅为的球形菌、水中球形Hp这3个实验组的胃粘膜组织快速尿素酶试验阳性率分别为93.8%（15／16）、87.5%(14/16)、50％（8／16）,由此反映在的细菌定居量评分为1.75、1.30、0.56,细菌培养阳性率分别为87.5%(14/16)、75.0%（12／16）、68.8%（11／16）,对照组阴性,Hp感染3w和4w的实验结果无差异。电镜下可见3个实验组均有弯曲形、杆状和球形Hp粘附于胃粘膜上。组织学检验发现感染的小鼠胃粘膜呈正常、轻度或重度糜烂、溃疡等不同的表现,有炎症细胞浸润。水中球形Hp感染引起的胃粘膜损伤较轻。结论 球形Hp可致胃炎或溃疡。     

Construction of a recombinant attenuated Salmonella typhimurium DNA vaccine carrying Helicobacter pylori hpaA

AIM: To construct a recombinant attenuated Salmonella typhimurium DNA vaccine carrying Helicobacter pylori hpaA gene and to detect its immunogenicity. METHODS: Genomic DNA of the standard H pylori strain 17 874 was isolated as the template, hpaA gene fragment was amplified by polymerase chain reaction (PCR) and cloned into pUCmT vector. DNA sequence of the amplified hpaA gene was assayed, then doned into the eukaryotic expression vector pIRES through enzyme digestion and ligation reactions. The recombinant plasmid was used to transform competent Escherichia coliDH5α, and the positive clones were screened by PCR and restriction enzyme digestion. Then, the recombinant pIRES-hpaA was used to transform LB5000 and the recombinant plasmid isolated from LB5000 was finally used to transform SL7207. After that, the recombinant strain was grown in vitro repeatedly. In order to identify the immunogenicity of the vaccine in vitro, the recombinant pIRES-hpaA was transfected to COS-7 cells using Lipofectamine~(TM)2000, the immunogenicity of expressed HpaA protein was detected with SDS-PAGE and Western blot. RESULTS: The 750-base pair hpaA gene fragment was amplified from the genomic DNA and was consistent with the sequence of H pylori hpaA by sequence analysis. It was confirmed by PCR and restriction enzyme digestion that H pylori hpaA gene was inserted into the eukaryotic expression vector pIRES and a stable recombinant live attenuated Salmonella typhimurium DNA vaccine carrying H pylori hpaA gene was successfully constructed and the specific strip of HpaA expressed by pIRES-hpaA was detected through Western blot. CONCLUSION: The recombinant attenuated Salmonella typhimurium DNA vaccine strain expressing HpaA protein with immunogenicity can be constructed and it may be helpful for further investigating the immune action of DNA vaccine in vivo.     

Use of the 'Polymerase Chain Reaction' for the diagnosis of Helicobacter pylori infection

PURPOSE: H. pylori infection can be diagnosed by means of non-invasive tests or invasive techniques using endoscopy. The choice of the test depends on available instruments, type of diseases, aim of diagnostic research (therapeutic or epidemiological) and test features. PCR is able to reveal pathogenic germs in biological material with very high sensitivity and specificity. In vitro DNA amplification method consists of hybriding denaturated DNA by means of two oligonucleotide primers that allow to copy DNA fragment. The aim of our study was to determine, using PER, H. pylori colonization in the gastric mucosa of 18 consecutive patients under-went gastroscopy. MATERIALS AND METHODS: Eighteen patients complaining of dyspeptic symptoms and referred to us for upper GI endoscopy participated in the study. The studied population comprised 9 males and 9 females with mean age of 55.4 yrs (range 26-73 years). All patients underwent gastroscopy during which 4 biopsies from the antrum and 4 from the corpus were obtained for Giemsa stain, PCR analysis and histologic examination. A pair of synthetic oligonucleotides for H. pylori urease A gene, designated as HPU1 and HPU2, were used. Urease A gene fragment amplified by PCR was analyzed by 1.5 agarose gel electrophoresis. Positivity for H. pylory corresponded to PCR DNA products migrating at 411 bp after staining with ethidium bromide. RESULTS: The patients were divided into two groups, according to H. pylori infection, determined by means of Giemsa stain: group A, comprising 11 H. pylori-positive patients; and group B, with 7 H. pylori-negative patients. Our PCR assay of gastric mucosa samples proved positive in 7 cases of group A (63.6%), whereas it always proved negative among group B subjects (100%). CONCLUSIONS: Our findings, apparently in contrast with the high sensitivity of PCR, may be attributed to the lower specificity of histology or, alternatively, the absence of H. pylori in the samples tested by PCR due to the patchy distribution of H. pylori colonization in the gastric mucosa. These observations are in agreement with those from other investigations.     

优化构建UreB/HpaA双价幽门螺杆菌减毒活菌疫苗的免疫保护作用

目的 以减毒鼠伤寒沙门菌为载体，通过在UreB和HpaA间引入由3个甘氨酸残基组成的三肽柔韧接头，构建成UreB／HpaA双价抗幽门螺杆菌(Hp)活疫苗，并对照相应单价疫苗和空白载体研究其对C57BL／6小鼠的免疫保护效果。方法 用序列重叠延伸聚合酶链反应扩增带3个甘氨酸残基柔韧接头的融合基因UreB／HpaA，进一步以减毒鼠伤寒沙门菌SL3261为载体构建UreB／HpaA双价活疫苗，观察其在小鼠体内的稳定性。用双价活疫苗株免疫Ⅱ级C57BL／6小鼠1次，对照单价活疫苗和空白载体观察其在体内诱导的特异抗体反应和对小鼠的免疫保护作用。结果 测序结果显示，3个甘氨酸残基的编码序列GGTGGAGGC已成功地插入UreB／HpaA融合基因中。双价疫苗灌喂小鼠后，至少能在脾脏和回肠末段存留10d。双价疫苗在小鼠体内诱导血清特异性IgGl和IgG2a水平明显升高。UreB／HpaA双价疫苗的免疫保护率为77．3％(17／22)，而UreB疫苗和HpaA疫苗的免疫保护率分别为50．0％(12／24)和43．5％(10／23)。结论 引入柔韧接头，优化构建表达UreB和HpaA的双价抗Hp活疫苗。UreB／HpaA双价活疫苗对Ⅱ级C57BL／6小鼠有更好的免疫保护作用。