幽门螺杆菌vacA基因型和cagA基因及其表达产物与胃十二指肠疾病的关系

幽门螺杆菌(Helicobacter pylori,Hp)感染是慢性胃炎(chronic gastritis,CG)和消化性溃疡(peptic ulcer,PU)的病因之一。也是胃癌(gastric cancer,GC)的危险因素。Hp的空泡形成毒素基因(vacuolating toxin gene,vacA)型和细胞毒素相关基因(cytotoxin-associated gene,cagA)及其表达产物——空泡形成细     

具有cagA,vacA基因的幽门螺杆菌与胃肠疾病

Ｈｐ感染后可导致不同的临床及病理结果，受感染者可形成慢性胃炎，胃或十二指肠球部溃疡、甚至胃癌。造成上述不同结果的机制尚不清楚。近年随着分子生物学技术的发展及应用，认为Ｈｐ菌株中ｃａｇＡ、ｖａｃＡ基因的存在与表达可能与上述结果的形成有关。本文就ｃａｇＡ、ｖａｃＡ基因的检测及其在胃肠疾病中的致病作用作一综述。     

广东地区幽门螺杆菌vacA基因亚型及其与胃肠疾病的关系

目的：探讨广东地区幽门螺杆菌（Ｈ．ｐｙｌｏｒｉ）ｖａｃＡ基因亚型的流行情况及不同ｖａｃＡ亚型与Ｈ．ｐｙｌｏｒｉ相关性胃肠疾病的关系。方法：自广东地区不同轩十二指肠疾病患者胃粘膜中分离得到１９１株Ｈ．ｐｙｌｏｒｉ菌株,抽提各菌株总ＤＮＡ,用特定引物对各菌株ｖａｃＡ基因的信号序列（ｓ）及中间区等位基因（ｍ）行矛合酶链反应（ＰＣＲ）检测。结果：广东地区患者Ｈ．ｐｙｌｏｒｉ的ｖａｃＡ亚型有ｓｌａ／ｍ２、ｓ     

幽门螺杆菌vacA毒性片段与cagA融合基因的构建与表达

目的　构建幽门螺杆菌空泡毒素 (VacA)毒性片段和细胞毒素相关蛋白 (CagA)的融合基因 (vlc) ,在原核细胞中表达 ,为Hp双价融合蛋白候选疫苗的研究提供材料。 方法　用GeneSOEing技术将vacA毒性亚单位片段 (v)与cagA保守片段 (c)用疏水性多肽接头 (Gly4Ser) 3 进行拼接 ,构建融合基因vlc,将vlc定向插入原核表达质粒pQE30 ,经DNA测序分析确认后 ,转化E .coliDH5a ,IPTG诱导表达 ,Westernblot分析其抗原性。结果　DNA序列分析表明融合基因的连接顺序、方向正确 ,有一个碱基发生了无义突变。工程菌诱导后可表达相对分子量为 5 8× 10 3 的融合蛋白 ,与预期分子量一致 ,约占菌体总蛋白的 8%。Westernblot显示融合蛋白具有良好的抗原性。结论　融合基因vlc构建成功 ,表达的融合蛋白具有良好的抗原性 ,有望进一步进行免疫保护性机制的研究和Hp疫苗的制备。     

幽门螺杆菌vacA基因型和cagA基因及其表达产物

幽门螺杆菌(Hp)的vacA基因和cagA基因分别表达VacA和CagA蛋白两种毒力因子。两种毒力因子之间有着相互的关联,在Hp引起的胃肠疾病中具有重要作用。Hp感染者的临床发病与Hp的vacA基因型、具有cagA基因Hp以及VacA和CagA蛋白的表达有着密切的关系。     

幽门螺杆菌vacA基因型和cagA基因及其表达产物

幽门螺杆菌（Ｈｐ）的ｖａｃＡ基因和ｃａｇＡ基因分别表达ＶａｃＡ和ＣａｇＡ蛋白两种毒力因子。两种毒力因子之间有着相互的关联，在Ｈｐ引起的胃肠疾病中具有重要作用，Ｈｐ感染的临床发病与Ｈｐ的ｖａｃＡ基因型，具有ｃａｇＡ基因Ｈｐ以及ＶａｃＡ和ＣａｇＡ蛋白的表达有着密切的关系。     

广东地区幽门螺杆菌空泡毒素基因亚型及其与胃肠疾病的关系

目的：1)调查广东地区患感染幽门螺杆菌(Hp)的空泡毒素基因(vacA)亚型的流行情况;2)探讨不同的vacA亚型与协相关胃肠疾病问的关系。方法：自广东地区不同疾病患胃黏膜中分离得到191株Hp,抽提各株菌的总DNA,采用特定引物对各株菌vacA基因中间序列(m)及信号序列(s)进行PCR检测。结果：1)广东地区患感染Hp vacA基因亚型有sla／m2、sla／mlb、slb／m2、slb／mlb、s2／m2及sla／mlb—m2六种组合、各亚型所占比例分别为88．0%(168／191)、7．3％(14／191)、3．1％(6／191)、0．5％(1／191)、0．5％(1／191)及0．5％(1／191);2)vacA亚型在不同Hp相关胃肠疾病中的检出率无显性差异。结论：1)广东地区Hp vacA基因亚型以sla／m2占绝大部份;2)不能单纯以vacA亚型作为预测感染Hp后的疾病转归。     

河西走廊地域幽门螺杆菌vacA和cagA基因型分布研究

[目的]探讨河西走廊胃癌高发区胃癌患者幽门螺杆菌(Helicobacter pylori,Hp)vacA和cagA基因型的分布情况,为当地Hp流行病学研究和疫苗研制提供参考。[方法]复苏和纯培养从河西走廊地域医院收集并分离到的89株Hp,抽提DNA,设计vacA信号序列s1a、s1b、s1c和cagA引物,PCR扩增vacA信号序列以及cagA基因并鉴定,分析Hp菌株中vacA和cagA基因型分布以及不同基因型与患者临床病理类型的关系。[结果]89 Hp菌株vacA基因均阳性,其中信号序列为s1a型者占66.29%,s1c型占33.71%,未见s1b型。vacA s1a基因型在慢性胃炎、消化性溃疡、胃癌各组中的构成比均高于s1c基因型。不同病理类型的疾病间,vacA s1a和s1c基因型构成均差异无统计学意义(P0.05)。cagA阳性率为97.75%,cagA+菌株在慢性胃炎、消化性溃疡、胃癌各组中的构成比均高于cagA-菌株。不同病理类型的疾病间,cagA+和cagA-菌株构成均差异无统计学意义(P0.05)。[结论]河西走廊地域Hp菌株大多数为致病性高的Ⅰ型菌株;vacA信号序列以s1a为主,其次为s1c;cagA+的高毒力菌株分布广泛,这可能是当地上消化道疾病高发的重要原因。     

胃癌组织中幽门螺杆菌cagA和vacA的表达及与其感染的相关性

目的:研究HpyloricagA和HpylorivacA在胃癌、胃黏膜不典型增生和胃炎组织中的表达及与Hpylori感染的相关性.方法:采用Warthin-Starry嗜银染色法检测胃癌组织39例,胃黏膜不典型增生组织24例和慢性胃炎组织33例中Hpylori感染情况;PCR法检测上述标本中HpyloricagA和HpylorivacA的表达.结果:胃癌组织中Hpylori,HpyloricagA 株和HpylorivacA 株感染率显著高于慢性胃炎组织(χ2=7.00,P<0.05;χ2=15.20,P<0.05;χ2=12.43,P<0.05);胃黏膜不典型增生组织中Hpylori,HpyloricagA 株和HpylorivacA 株感染率显著高于慢性胃炎组织(χ2=6.25,P<0.05;χ2=11.04,P<0.05;χ2=11.61,P<0.05);低分化胃癌组织中Hpylori,HpyloricagA 和HpylorivacA 株感染率显著高于高中分化胃癌组织(χ2=8.19,P<0.05;χ2=13.14,P<0.05;χ2=6.62,P<0.05).慢性胃炎、不典型增生和胃癌组织中Hpylori与HpyloricagA和HpylorivacA表达均呈正相关(慢性胃炎:r=0.56,P<0.01;r=0.64,P<0.01;不典型增生组织:r=0.64,P<0.01;r=0.92,P<0.01;胃癌:r=0.90,P<0.01;r=0.95,P<0.01).结论:Hpylori感染是慢性胃炎向胃黏膜不典型增生及胃癌发展的重要启动因子,Hpylori感染可能通过诱导cagA表达促使胃黏膜上皮细胞增殖加快,诱导vacA表达促使胃黏膜上皮细胞损伤;他们的协同作用可能在胃癌发生、发展过程中发挥了重要作用.     

60例上消化道疾病患者幽门螺杆菌vacA基因分型检测及意义

目的 探讨幽门螺杆菌(HP)空泡毒素(vacA)基因及亚型与上消化道疾病的关系.方法 应用聚合酶链反应法测定60例上消化道疾病患者胃黏膜分离获得的HP vacA基因及亚型.用特异的16s rDNA聚合酶链反应进行临床分离HP的菌种鉴定.结果 HP vacA基因主要以s1a-m2型为主,除此以外,s1a-m1、s1b-m1、s1b-m2型均有分布.结论 HP相关性上消化道疾病患者感染的HP菌株以vacA s1a-m2亚型占优势,检测vacA s1a-m2基因亚型有助于上消化道疾病诊断.     

Prevalence of vacA, cagA and babA2 genes in Cuban Helicobacter pylori isolates

AIM： To investigate the prevalence of vacuolating cytotoxin （vacA）, cytotoxin associated gene A （cagA） and blood adhesion binding antigen （babA2） genotypes of Helicobacter pylori （H pylori） isolates from Cuban dyspeptic patients. METHODS： DNA was extracted from Hpylori-positive cultures taken from 130 dyspeptic patients. Genotyping was performed by PCR, using specific primers for vacA （s1, s2, m1, m2）, cagA and babA2 genes. Endoscopic observations and histological examinations were used to determine patient pathologies. RESULTS： vacA alleles s1, s2, m1 and m2 were detected in 96 （73.8%）, 34 （26.2%）, 75 （57.7%） and 52 isolates （40%）, respectively, while the cagA gene was detected in 95 isolates （73.2%）. One hundred and seven isolates （82.3%） were babA2-positive. A significant correlation was observed between vacAs1m1 and cagA and between vacAs1ml and babA2 genotypes （P 〈 0.001 and P 〈 0.05, respectively） and between babA2 genotype and cagA status （P 〈 0.05）; but, no correlation was observed between vacAsl and babA2 genotypes. Eighty five （65.4%） and 73 （56.2%） strains were type 1 （vacAsl-cagA-positive） and ＂triplepositive＂ （vacAs1-cagA-babA2-positive）, respectively, and their presence was significantly associated with duodenal ulcer （P 〈 0.01 and P 〈 0.001, respectively）. CONCLUSION： The distribution of the main virulence factors in the Cuban strains in this study resembled that of the Western-type strains, and the more virulent H pylori isolates were significantly associated with duodenal ulcer, ulcer disease being the worst pathology observed in the group studied.     

Significance of cagA status and vacA subtypes of Helicobacter pylori in determining gastric histopathology: virulence markers of H. pylori and histopathology

BACKGROUND: It has been suggested that Helicobacter pylori strains containing the cytotoxin-associated gene A (cagA), and s1m1 genotype of vacuolating cytotoxin gene A (vacA) may have been associated with peptic ulcer disease. The aim of the present study was to analyze such an association of cagA presence and vacA subtypes of H. pylori with histopathological findings in patients with gastritis. METHODS: Sixty-five independent H. pylori strains isolated from Turkish patients with gastritis were analyzed. The antral biopsy specimens were processed for culture and histopathology. Histopathological features were recorded and graded according to updated Sydney system. The vacA subtypes and cagA gene were tested by polymerase chain reaction. RESULTS: Mild degree of antral density was associated with mild degree of gastric neutrophil infiltration (P = 0.010). Positive cagA status correlated significantly with the presence of atrophy (P = 0.035) and neutrophil infiltration (P < 0.001), but not with H. pylori density (P = 0.754) nor the degree of mononuclear cell infiltration (P = 0.945). The vacA subtypes were independent of gastric histopathology. The odds ratios for atrophy and neutrophil infiltration of cagA+ versus cagA- strains were 3.62 (95% confidence interval [CI]: 1.04-12.66) and 53.18 (95%CI: 11.08-255.23), respectively. CONCLUSION: The presence of the cagA gene is strongly associated with atrophic and active gastritis. Distinct vacA subtypes of H. pylori appear to have no association with histopathological findings of gastritis.     

Importance of Helicobacter pylori cagA and vacA status for the efficacy of antibiotic treatment

BACKGROUND: Virulence factors of Helicobacter pylori are associated with peptic ulcer disease and may be also associated with the efficacy of treatment. AIMS: To determine the relation between the vacA and the cagA status of H pylori, clinical disease, and treatment outcome. PATIENTS: 121 patients with H pylori infection and peptic ulcer disease or functional dyspepsia were treated by quadruple antibiotic therapy in two groups for one and two days, respectively. METHODS: DNA was isolated from gastric antral biopsy specimens, taken before and after treatment, and the vacA and cagA status was determined by polymerase chain reaction and reverse hybridisation. RESULTS: Peptic ulcer disease was significantly associated with the vacA s1 type, and cagA positivity, but not with the vacA m type. Treatment efficacy was significantly higher in patients with peptic ulcer disease, or infected with cagA+/vacA s1 strains. CONCLUSIONS: The strong association between the cagA and vacA status and peptic ulcer disease was confirmed. Cure rates seem to be higher for patients with cagA+/vacA s1 H pylori strains, which is consistent with the higher cure rate observed among ulcer patients compared with functional dyspepsia patients. Therefore, treatment studies may require stratification for presence of ulcers as well as H pylori genotypes.     

Analysis of Helicobacter pylori vacA and cagA genotypes and serum antibody profile in benign and malignant gastroduodenal diseases

BACKGROUND: Helicobacter pylori species comprise different strains, cytotoxic and non-cytotoxic, which can be identified on the basis of their genomic pattern. AIMS: (1) To evaluate the polymorphism of the vacA gene and to ascertain whether the cagA gene is present in patients with gastric adenocarcinoma. (2) To study the anti-H pylori antibody profile using western blotting. PATIENTS: Twenty one patients with gastric adenocarcinoma and 71 with H pylori associated benign disease (nine gastric ulcer, 29 duodenal ulcer, 25 antral gastritis, and eight duodenitis). METHODS: The polymerase chain reaction was used to verify the presence or absence of cagA and to study the polymorphism of vacA in gastric mucosal samples obtained during endoscopy for patients with benign diseases and at surgery for patients with gastric adenocarcinoma. Fasting sera were used to assess anti-H pylori antibodies against different H pylori antigens by western blotting. RESULTS: CagA gene and the allele s1 of vacA were significantly less frequent in patients with antral gastritis (60% and 60%) compared with patients with gastric adenocarcinoma (94% and 100%) and with other non-malignant gastroduodenal diseases (93% and 87%) (chi 2 = 16.01, p < 0.001; and chi 2 = 13.97, p < 0.01). In patients with gastric adenocarcinoma, antibodies against a 74 kDa H pylori antigen were less frequently found than in patients with benign diseases. CONCLUSIONS: H pylori infection caused by cagA positive/vacA s1 strains is a frequent finding in patients with gastric adenocarcinoma. Prospective studies are needed to confirm whether the low incidence of positive serological response to the 74 kDa H pylori antigen in patients with gastric adenocarcinoma is important.     

贵阳地区幽门螺杆菌临床分离株中ureA、cagA、vacA、iceA基因的分布及分析

目的了解贵阳地区临床分离的幽门螺杆菌（Hp）的毒力基因ureA、cagA、vacA、iceA的分布特征,探讨不同毒力基因型与上消化道疾病的关系。方法用特异的16SrDNA聚合酶链反应进行临床分离Hp的菌种鉴定,对经过鉴定的152株幽门螺杆菌进行ureA、cagA、vacA、iceA基因及亚型的PCR检测。结果 ureA基因的检出率为100%（152/152）,vacA基因的检出率为100%（152/152）,vacA基因亚型以s1a-m2型为主,占76.3%（116/152）,cagA基因检出率为39.5%（60/152）,ieeA1基因检出率36.8%（56/152）,iceA2基因检出率为34.2%（52/152）,13.2%（20/152）的菌株iceA1和iceA2基因均阳性,不同基因型菌株在慢性胃炎和消化性溃疡中的检出率无统计学意义（P〉0.05）。结论贵阳地区幽门螺杆菌毒力基因vacA以s1a-m2型为主,cagA阴性比例高于cagA阳性,不同基因型菌株与消化性疾病间无明显相关性。     

幽门螺杆菌vdcA基因多态性与慢性胃病的关系

目的探讨幽门螺杆菌(HP)vdcA基因多态性与慢性胃病的关系.方法经胃镜检查活检胃粘膜标本,分离鉴定Hp,酚氯仿方法抽提DNA,聚合酶链反应检测vdcA基因的信号区(s)和中间区(m).结果92例Hp临床分离株中,sla/ml型14株(15.2)、sla/mla型6株(6.5%)、s2/m2型8株(8.7%)、slb/ml型2株(2.2%)、slb/m2型5株(5.4%)、s2/m2型8株(8.7%),另在2株slaHP不能按ml、mla或m2进一步分型,未发现s2/ml、slb/mla及s2/mla型.除4例胃癌外,其余88例按消化性溃疡和慢性胃炎分组,40例消化性溃疡患者感染Hp中sla型37例,占92.5%,slb型2株(5%),s2型1株(2.5%);ml型4株(10%),mla型2株(5%),m2型32株(80%),另有2株sla型Hp未能按ml、mla或m2进一步分型.48例慢性胃炎患者感染Hp中sla型36株,占75%,slb型5株(10.4%),s2型7株(14.6%);ml型11株(22.9%),mla型4株(8.3%)m2型33株(68.8%).消化性溃疡组和慢性胃炎组均以sla型、m2型为主,分别比较两组间sla型及m2型的分布,两组间sla型有显著性差异(P＜0.05),而m2型无显著性差异(P＞0.05).结论慢性胃病患者感染Hp主要为sla/m2型,其次为sla/ml型.Sla型Hp与消化性溃疡的发生密切相关.     

Helicobacter pylori cagA, iceA and vacA status in Taiwanese patients with peptic ulcer and gastritis

BACKGROUND: Helicobacter pylori causes chronic gastritis, peptic ulcer, gastric cancer and mucosa-associated lymphoid tissue (MALT) lymphoma. Different genotypes of H. pylori are confirmed from diverse geographical areas. Its association with clinical diseases remains controversial. The aim of the present study was to investigate the H. pylori vacuolating cytotoxin (vacA) alleles, cytotoxin-associated gene (cagA) and iceA, in patients with peptic ulcer and gastritis. METHODS: We enrolled patients with peptic ulcer and chronic gastritis. Biopsy specimens were obtained from the antrum and lower body of the stomach. DNA extraction and polymerase chain reaction (PCR) were used to detect the presence or absence of cagA and to assess the polymorphism of vacA and iceA. RESULTS: A total of 133 patients (57 gastric ulcer, 52 duodenal ulcer, 24 chronic gastritis) had positive PCR results from biopsy specimens. Concerning genotypes, we found cagA (79% in the antrum, 92% in the body) and iceA1 (73% in the antrum, 82.8% in the body) strains in the majority of patients. The dominant vacA subtype was s1a (74.4% in the antrum, 75% in the body), followed by s1c (51.1% in the antrum, 60.5% in the body). In the middle region, the m2 strain dominated (49.6% in the antrum, 41.4% in the body), followed by m1T (19.5% in the antrum, 9.5% in the body). Mixed infection occurred in 89 patients (67%). There was no statistical difference in genotypes among the three groups. CONCLUSION: In Taiwan, H. pylori with positive cagA and iceA1 was found in the majority of cases. H. pylori with vacA s1a strains was the most common vacA subtype, followed by s1c, while s1b was rare. In the middle region, the m2 subtype was predominant followed by m1T. There was no significant association between genotypes and clinical diseases.     

Helicobacter pylori vacA genotypes and cagA status and their relationship to associated diseases

Helicobacter pylori (H. pylori ) is a major causativebacterium of chronic gastritis, peptic ulcer and mucosaassociated lymphoid tissue lymphoma in humans, and associated with an increased risk of gastric cancer[1 -8]. An important virulant factor of H. pylori is the vacuolating cytotoxin ( VacA ) encoded by vacA that induces cytoplasmic vacuolation in target cells both in vitro and in vivo[9-11]. VacA is produced as a 140 kDa precursor which contains an N-terminal signal peptide and an approximately 33 kDa C-terminal outer membrance exporter. The precursor is cleaved at both N-terminal and C-terminal and secreted into the extracellular milieu as a 95 kDa mature protein. The mature protein futher undergoes specific cleavage to yield 37 kDa and 58 kDa subunits[12-14] Although vacA is present in all H. pylori strains, only about 50% to 60% of strains can induce vacuolation of epithelial cells as assessed by the HeLa cell assay. vacA shows considerable genetic variation in H. pylori isolated from all over the world and contains at least two variable regions. The s region exists as sl or s2 allelic types. Among type sl strains, subtypes sla and slb have been identified. The m region occurs as ml or m2 allelic types. Specific vacA genotype of H. pylori strains are associated with the production of the cytotoxin in vitro, epithelial damage in vivo, and clinical consequences[15-27]. The other virulant factor is the cytotoxin-associated protein (CagA) encoded by the cytotoxin-associated gene (cagA). The cagA gene is present in about 60% to 70% of strains and all of these strains express the cagA. The presence of cagA is also associated with the production of the cytotoxin in vitro, and clinical outcome[24-30]. The aim of this study was (i) to identify vacA genotypes and cagA status of H. pylori isolated from Chinese patients; (ii) to evaluation the relatioship beween vacA genotypes, cagA status and related gastroenterological disorders.