幽门螺杆菌cagA及vacA亚型与胃肠疾病的关系

目的调查石家庄地区慢性胃病患者感染幽门螺杆菌(H·pylori)的细胞毒素相关基因(cagA)及空泡毒素基因(vacA)亚型的流行情况;探讨H·pylori cagA、vacA亚型与胃肠疾病的关系。方法自石家庄地区慢性胃病患者胃黏膜中分离得到55株H·pylori,抽提各菌株的总DNA,采用特定引物对各菌株cagA3′端、vacA信号序列(s)及中间序列(m)进行PCR检测。结果H·pylori cagA的阳性者占89·1%(49/55),其在慢性胃炎和消化性溃疡中的阳性率差异无显著性(χ2=0·376,P=0·540)。H·pylori vacA基因亚型有s1a/m2、s1a/m1b-m2、s1a/m1b三种组合,各亚型所占比例分别为90·4%(47/52)、5·8%(3/52)、3·8%(2/52),其中最常见的vacA亚型s1a/m2在慢性胃炎与消化性溃疡中的阳性率差异无显著性(χ2=0,P=1·000)结论石家庄地区慢性胃病患者感染的幽门螺杆菌以cagA 、vacA s1a/m2亚型占优势,未发现H·pylori cagA及vacA亚型与特定胃肠疾病间存在显著相关性。     

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.     

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。     

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.     

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。     

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.     

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.     

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.     

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。     

Helicobacter pylori density and cagA status in cirrhotic patients: a case-control study

BACKGROUND AND AIM: Despite a similar Helicobacter pylori prevalence, peptic ulcer is more frequent in cirrhotic patients than in controls. We evaluated whether cirrhotic patients had an increased bacterial density and/or a higher prevalence of H. pylori cagA-positive strains than controls. METHODS: A total of 36 dyspeptic cirrhotic patients with H. pylori infection and 72 matched controls were enrolled. H. pylori infection was detected at histology on Giemsa staining, bacterial density was assessed using difference over baseline (DOB) values at 13C urea breath test, and cagA status was established at serology. RESULTS: Overall, both DOB values and prevalence of cagA did not significantly differ between cirrhotic patients and controls. However, peptic ulcer controls showed significantly higher DOB value (27.9 +/- 17.4 vs 19.4 +/- 9.3, respectively; P = 0.009) and cagA positive rate (85%vs 48%; P = 0.01) than non-ulcer dyspepsia patients. Although not statistically significant, a similar trend was observed in cirrhotic patients with peptic ulcer for DOB values (26.5 +/- 16.3 vs 18.3/1000 +/- 9.2, respectively; P = 0.07), whereas the cagA-positive rate was similar between peptic ulcer and non-ulcer dyspepsia patients (60%vs 50%; P = 0.30). CONCLUSIONS: The present data showed that both bacterial density and cagA prevalence did not differ between cirrhotic patients and controls.     

Association of peptic ulcer with increased expression of Lewis antigens but not cagA, iceA, and vacA in Helicobacter pylori isolates in an Asian population

BACKGROUND: Studies in Western populations suggest that cagA, iceA, and vacA gene status in Helicobacter pylori isolates is associated with increased virulence and peptic ulcer disease. AIM: To investigate the relationship between peptic ulcer and expression of Lewis (Le) antigens as well as cagA, iceA, and vacA in H pylori isolates in Singapore. METHODS: Expression of Le antigens in H pylori isolates obtained from patients with dyspepsia was measured by enzyme linked immunosorbent assay. The cagA, iceA, and vacA status was determined by polymerase chain reaction. RESULTS: Of 108 H pylori isolates, 103 (95.4%) expressed Le(x) and/or Le(y), while Le(a) and Le(b) were expressed in 23 (21.3%) and 47 (43.5%) isolates, respectively. Expression of two or more Le antigens (Le(x), Le(y), Le(a), or Le(b)) was significantly higher in H pylori isolated from ulcer patients than in non-ulcer patients (89.6% v 73.2%, p=0.035). There were no significant differences in the prevalence of cagA or iceA1 in H pylori isolates from peptic ulcer and non-ulcer patients (86.6% v 90.2% for cagA; 70.1% v 68.3% for iceA1), and no association of peptic ulcer with any specific vacA genotype. CONCLUSIONS: The present study indicates that peptic ulcer disease is associated with increased expression of Lewis antigens but not cagA, iceA, or vacA genotype in H pylori isolates in our population. This suggests that cagA, iceA, and vacA are not universal virulence markers, and that host-pathogen interactions are important in determining clinical outcome.     

幽门螺杆菌vacA基因PCR-RFLP分型

目的为幽门螺杆菌(Helicobacterpylori,简称Hp)的基因分型提供一种可选择的指标,并通过分型与空泡毒素(vacuolatingcytotoxingeneAproduct,VacA)表达情况分析HpvacA基因的多态性。方法用自行设计的引物对18株Hp的vacA基因进行扩增,用7种限制性内切酶对基因扩增产物进行限制性片段长度多态性(RestrictionFragmentLengthPolymorphism,RFLP)分析;通过细胞测毒法对18株HpVacA活性进行检测。结果18株Hp的vacA扩增产物为2.75kb左右,但长度有差异;只有HeaⅢ可将vacA基因切出整齐的谱型,18株Hp被分为12种谱型。未发现VacA表达相关的谱型。结论HpvacA基因具有一定的多态性,而vacA基因的PCR产物经HeaⅢ酶切的RFLP分型可作为Hp基因分型的较理想选择指标。为Hp分子流行病学调查提供一种有效方法。     

靶向siRNA抑制幽门螺杆菌vacA表达

目的:观察靶向siRNA能否抑制幽门螺杆菌(H pylori)vacA基因表达．方法:合成靶向H pyiori vacA基因5对特异 siRNA(实验组:vacA-S1,vacA-S2,vacA-S3, vacA-S4,vacA-S5)和1对非特异siRNA(对照组)．通过电穿孔法使siRNA转化至H pylori内,观察转化效率和转化1,6,12,24,48 h mRNA和蛋白表达的抑制率,并将PCR产物克隆和测序. 结果:电穿孔转化效率平均为89％．vacA-S2、 vacA-S4组在转化1 h vacA mRNA表达抑制率达最大值,1,6,12 h抑制率分别为65％和77％,43％和50％,17％和9％,24和48 h时 vacA mRNA表达无抑制效应,与vacA-S1、 vacA-S3、vacA-S5、vacA-S6组相比有显著差异 (P<0．05),因为vacA-S1、vacA-S3、vacA-S5、 vacA-S6组转化后各时间点mRNA表达无变化．vacA-S2和vacA-S4组在转化1,6,12,24 h时 vacA蛋白表达抑制率分别为26％和17％,47％和40％,70％和75％,33％和30％,与vacA-S1、 vacA-S3、vacA-S5、vacA-S6组相比有显著差异 (P<0．05);转化48 h则无抑制效应．PCR产物克隆和测序与相应报道序列比较,同源性为99％．结论:靶向siRNA可以通过电穿孔法转化并特异地抑制H pylori vacA基因表达.     

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.     

Diversity of Helicobacter pylori genotypes in Iranian patients with different gastroduodenal disorders

AIM:To investigate the diversity of Helicobacter pylori(H.pylori)genotypes and correlations with disease outcomes in an Iranian population with different gastroduodenal disorders.METHODS:Isolates of H.pylori from patients with different gastroduodenal disorders were analyzed after culture and identification by phenotypic and genotypic methods.Genomic DNA was extracted with the QIAamp DNA mini kit(Qiagen,Germany).After DNA extraction,genotyping was done for cagA,vacA(s and m regions),iceA(iceA1,iceA2)and babA with specific primers for each allele using polymerase chain reaction(PCR).All patients’pathologic and clinical data and their relation with known genotypes were analyzed by using SPSS version 19.0 software.2test and Fisher’s exact test were used to assess relationships between categorical variables.The level of statistical significance was set at P<0.05.RESULTS:A total of 71 isolates from 177 patients with different gastroduodenal disorders were obtained.Based on analysis of the cagA gene(positive or negative),vacA s-region(s1or s2),vacA m-region(m1or m2),iceA allelic type(iceA1and iceA2)and babA gene(positive or negative),twenty different genotypic combinations were recognized.The prevalence of cagA,vacA s1,vacA s2,vacA m1,vacA m2,iceA1,iceA2,iceA1+iceA2and babA were 62%,78.9%,19.7%,21.1%,78.9%,15.5%,22.5%,40.8%and 95.8%,respectively.Interestingly,evaluation of PCR results for cagA in 6 patients showed simultaneous existence of cagA variants according to their size diversities that proposed mixed infection in these patients.The most prevalent genotype in cagA-positive isolates was cagA+/vacAs1m2/iceA1+A2/babA+and in cagA-negative isolates was cagA-/vacAs1m2/iceA-/babA+.There were no relationships between the studied genes and histo-pathological findings(H.pylori density,neutrophil activity,lymphoid aggregation in lamina propria and glandular atrophy).The strains which carry cagA,vacAs1/m1,iceA2and babA genes showed significant associations with severe active chronic gastritis(P=0.011,0.025,0.020 and     

Analysis of Helicobacter pylori vacA Gene and Serum Antibodies to VacA in Japan

Vacuolating cytotoxin, VacA, is one of the most important pathogenetic factors produced by Helicobacter pylori. However, it is not clear whether the diversity in disease outcome may be ascribed to variations in strain and/or to the host responses to virulence factors. In this study, we analyzed the vacA middle region sequence among 65 Japanese isolates to clarify the variation in strain and assayed antibody titer to VacA by ELISA using purified VacA to evaluate the host response to cytotoxin. The nucleotide sequence identities compared among Japanese isolates were 92.8 ± 3.56%, and compared to 88.3 ± 2.89% in tox⁺ strains reported in GenBank. Positive correlation was found between the antibody titers and the severity of atrophic change of the stomach. In Japan the nucleotide sequences of the vacA middle region were highly homologous and genetically closer to tox⁺ strains. Antibody titers and host response to cytotoxin may be associated with atrophy of the stomach.     

Effects of cagA+ and cagA- strains of Helicobacter pylori on the human gastric mucus layer thickness

BACKGROUND: Infection with cytotoxin-associated gene A (cagA) Helicobacter pylori is associated with severe gastric diseases, with contradictory views being expressed concerning the effect of H. pylori on the gastric mucus thickness. The aim of the present study was to differentiate between the effect of cagA+ and cagA- strains on gastric mucus thickness. METHODS: Ninety-nine patients without peptic ulcers who were not on medication were randomly recruited from consecutive endoscopy clinics: six biopsies (five antral, one body) were obtained from each patient. Cryostat sections (18 microm) were cut and stained using the modified periodic acid-Schiff/Alcian blue technique. Mucus thickness was measured using computer-assisted light microscopy. The H. pylori status was assessed by histology, Campylobacter-like organism (CLO)test and culture, and cagA+ status determined by polymerase chain reaction (PCR). RESULTS: There was no significant difference (P = 0.784) in mean mucus thickness between cagA+ (52.7 +/- 1.2 microm, n = 10), cagA- (46.6 +/- 1.1 microm, n = 18) or H. pylori-negative patients (51.3 +/- 1.1 microm, n = 30). In cagA- patients, mucus thickness was significantly reduced with increased H. pylori colonization density, Spearman (r(s)) = -0.805, P < 0.0001. In contrast, in cagA+ patients there was a weak positive, but not significant, association between mucus thickness and H. pylori colonization density, r(s) = 0.333, P = 0.381. CONCLUSIONS: The human gastric mucus thickness is not affected by infection with cagA+ or cagA- strains of H. pylori compared with uninfected. Although a trend of increased mucus thickness with cagA+ infection was observed.     

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.     

Helicobacter pylori in dental plaque and stomach of patients from Northern Brazil

AIM: To establish whether virulence factor genes vacA and cagA are present in Helicobacter pylori (H. pylori) retrieved from gastric mucosa and dental plaque in pa-tients with dyspepsia. METHODS: Cumulative dental plaque specimens and gastric biopsies were submitted to histological exami-nation, rapid urease test and polymerase chain reac-tion (PCR) assays to detect the presence of cagA and vacA polymorphisms.RESULTS: Detection of H. pylori from dental plaque and gastric biopsy samples was greater by PCR co...