dupA Gene Research Articles

The association between Helicobacter pylori virulence factor genotypes and gastroduodenal diseases in children

Objective: To investigate the association between Helicobacter pylori (Hp) virulence factor genotypes and the degree and activity of gastric mucosa pathological changes in pediatric gastroduodenal diseases. Methods: This retrospective cohort study was conducted from May 2020 to October 2020. The frozen strains of Hp, which were cultured with the gastric mucosa of 68 children with gastroscopy confirmed gastroduodenal diseases who visited the children's hospital of Zhejiang University School of Medicine from April 2012 to December 2014, were resuscitated. After extracting DNA from these Hp strains, PCR amplification and agarose gel electrophoresis were performed to determine the detection rate of cytotoxin-associated protein A (cagA),vacuolating cytotoxin A (vacA)(s1a、s1b/s2,m1/m2), outer inflammatory protein A (oipA),blood group antigen binding adhesin (babA),duodenal ulcer promoting protein A (dupA) genes; oipA genes were sequenced to determine the gene status. The patients were divided into different groups according to the findings of gastroscopy and gastric mucosa pathology. The detection rates of various virulence factor genotypes among different groups were compared using χ2 tests or Fisher's exact tests. Results: The 68 Hp strains all completed genetic testing. According to the diagnostic findings of gastroscopy, the 68 cases were divided into 47 cases of superficial gastritis and 21 cases of peptic ulcer. Regarding the pathological changes of gastric mucosa, 8 cases were mild, and 60 cases were moderate and severe according to the degree of inflammation; 61 cases were active and 7 cases inactive according to the activity of inflammation. The overall detection rates of cagA, vacA, vacA s1/m2, functional oipA, babA2, and dupA virulence factor genes were 100% (68/68), 100% (68/68), 94% (64/68), 99% (67/68), 82% (56/68), and 71% (48/68), respectively. In the superficial gastritis group, their detection rates were 100% (47/47), 100% (47/47), 96% (45/47), 98% (46/47), 81% (38/47), and 70% (33/47), respectively; in the peptic ulcer group, their detection rates were 100% (21/21), 100% (21/21), 90% (19/21), 100% (21/21), 86% (18/21), and 71% (15/21), respectively. There was no statistically significant difference between the two groups (all P>0.05). In the mild gastric mucosa inflammation group, the detection rates of the above six genotypes were 8/8, 8/8, 8/8, 7/8, 7/8, and 5/8, respectively; and in the moderate to severe inflammation groups, the detection rates were 100% (60/60), 100% (60/60), 93% (56/60), 100% (60/60), 82% (49/60), and 72% (43/60), respectively, with no statistically significant difference between the two groups (all P>0.05). In the active inflammation group, the detection rate of six genotypes were 100% (61/61), 100% (61/61), 93% (57/61), 98% (60/61), 82% (50/61), and 72% (44/61), respectively; and in the inactive inflammation group, they were 7/7, 7/7, 7/7, 7/7, 6/7, and 4/7, respectively. Again, there was no statistically significant difference between the two groups (all P>0.05). There was no statistically significant difference in the detection rate of combinations of 4 or 5 virulence factor genes among the different groups (all P>0.05). Conclusions: CagA, vacA, vacA s1/m2, functional oipA, babA2, and dupA genes are not associated with superficial gastritis and peptic ulcer in children, or with the degree and activity of gastric mucosa pathological inflammation. Different gene combinations of cagA, vacA, oipA, babA2, and dupA have no significant effects on predicting the clinical outcome of Hp infection in children.

STUDY ON THE PRESENCE OF OIPA AND DUPA GENES OF HELICOBACTER PYLORI IN GASTRIC CANCER PATIENTS

Objectives: To determine the percentage of Helicobacter pylori (H. pylori) carrying the outer inflammatory protein A (oipA), duodenal ulcer promotion (dupA) genes, and their relationship with endoscopic imaging, histopathology, and the risk of gastric cancer (GC). Subjects and methods: A cross-sectional study on 89 GC patients, compared with 90 patients with chronic gastritis (CG) with H. pylori infection, diagnosis based on histopathological results at Military Hospital 103 and Central Military Hospital 108 from August 2019 to May 2022. Determination of oipA, dupA genes of H. pylori by realtime-PCR technique on biopsy tissue samples of the gastric mucosa. Results: The percentage of H. pylori carrying the oipA and dupA genes was 30.2% and 10.1%, respectively. The relationship between bacterial infection harboring these 2 genes and endoscopic images and histopathology of GC has not been recorded. There was no difference in the prevalence of H. pylori carrying the oipA and dupA genes infection between the GC and CG groups (p > 0.05). Conclusion: The infection of H. pylori with oipA and dupA genes positive may not increase GC risk in Vietnamese.

The cagA, cagE, vacA, dupA and iceA1 genes of Helicobacter pylori in Sudanese gastritis patients: Distribution and relationship with clinical outcomes and histological alterations

The cagA, cagE, vacA, dupA and iceA1 genes of Helicobacter pylori in Sudanese gastritis patients: Distribution and relationship with clinical outcomes and histological alterations

Helicobacter pylorivirulence dupA gene: risk factor or protective factor?

Helicobacter pylori is the etiological agent of chronic gastritis, peptic ulcer, and gastric cancer. The duodenal ulcer-promoting gene dupA, which is located in the plasticity region of the H. pylori genome, is homologous to the virB gene which encodes a type IV secretion protein in Agrobacterium tumefaciens. Studies have shown associations between H. pylori dupA-positive strains and gastroduodenal diseases. However, whether dupA acts as a risk factor or protective factor in these diseases remains unclear. Therefore, in this study, we aimed to verify the presence of the dupA gene in infectious H. pylori strains in the Brazilian mid-west and to investigate its association with the clinical outcomes of patients with dyspepsia. Additionally, the phylogenetic origin of the strains was determined. Gastric biopsies from 117 patients with dyspepsia were analyzed using histological and molecular techniques. The hpx gene (16S rRNA) was used to screen for H. pylori infection, and positive samples were then subjected to dupA gene detection and sequencing. The estimated prevalence of H. pylori infection was 64.1%, with the dupA gene being detected in a high proportion of infectious strains (70.7%). Furthermore, a risk analysis revealed that for women, a dupA-positive H. pylori infection increased the chance of developing gastritis by twofold. The partial dupA sequences from isolated infectious strains in this work are similar to those of strains isolated in westerns countries. This study provides useful insights for understanding the role of the H. pylori dupA gene in disease development.

Geographic distribution of the cagA, vacA, iceA, oipA and dupA genes of Helicobacter pylori strains isolated in China

BackgroundThere are geographic variations in the genotypes of Helicobacter pylori (H. pylori) cagA, vacA, iceA, oipA and dupA. The aim of the study was to investigate the distribution of these genotypes among H. pylori strains from five regions of China and their association with clinical outcomes.Materials and methodsGastric biopsy specimens were obtained from 348 patients with different gastrointestinal diseases in the five regions of China. The regional distribution was 89 patients from Shandong, 91 from Guangxi, 57 from Hunan, 58 from Qinghai and 53 from Heilongjiang. The presence of cagA, vacA, iceA, oipA and dupA genotypes was determined by polymerase chain reaction (PCR) from H. pylori DNA.ResultsA total of 269 H. pylori isolates were obtained, of which 74 isolates were from Shandong, 78 from Guangxi, 46 from Hunan, 33 from Qinghai and 38 from Heilongjiang. The cagA-positive status was predominant in the five regions. The predominant vacA genotypes were s1c (73.4%), m2 (70.6%) and i1 (92.9%). In strains from Shandong, s1a and m1 were dominant. By contrast, s1c was dominant in Guangxi and i1 was dominant in Hunan and Heilongjiang. The prevalence of m2 subtype in Qinghai (78.8%) was significantly higher than that in other regions (P < 0.05). The predominant iceA genotype was iceA1 and the frequency of iceA1 was significantly more prevalent in Hunan than in other regions (P < 0.05). The oipA status “on” gene was more frequent in Shandong (91.9%) and Guangxi (91%) than in Heilongjiang (71.7%) (P < 0.05). Conversely, the dupA-positive status was less than half in Shandong (31.1%) and Guangxi (15.4%), whereas it was 73.9% in Hunan and 81.8% in Qinghai (P < 0.001). There were no significant associations between the cagA, vacA, iceA, oipA genotypes and clinical outcomes. The dupA-positive strains were more common in peptic ulcer disease (PUD) patients than in non-ulcer dyspepsia (NUD) patients in Shandong and Guangxi (P < 0.05), but the association was not observed in other geographic regions.ConclusionsThere was significant geographic diversity of H. pylori genotypes in different regions of China and the presence of dupA gene can be considered as a marker for the development of gastroduodenal diseases. However, the cagA, iceA, vacA and oipA genes cannot be regarded for prediction of the clinical presentation of H. pylori infection in China.

Novel virulence factor dupA of Helicobacter pylori as an important risk determinant for disease manifestation: An overview.

Helicobacter pylori (H. pylori) is a microaerophilic, Gram-negative, human gastric pathogen found usually in the mucous lining of stomach. It infects more than 50% of the world’s population and leads to gastroduodenal diseases. The outcome of disease depends on mainly three factors: Host genetics, environment and bacterial factors. Among these, bacterial virulence factors such as cagA, vacA are well known for their role in disease outcomes. However, based on the global epidemiological results, none of the bacterial virulence (gene) factors was found to be associated with particular diseases like duodenal ulcer (DU) in all populations. Hence, substantial importance has been provided for research in strain-specific genes outside the cag pathogenicity island, especially genes located within the plasticity regions. dupA found within the plasticity regions was first demonstrated in 2005 and was proposed for duodenal ulcer development and reduced risk of gastric cancer in certain geographical regions. Due to the discrepancies in report from different parts of the world in DU development related to H. pylori virulence factor, dupA became an interesting area of research in elucidating the role of this gene in the disease progression. In this review, we shed light on the detailed information available on the polymorphisms in dupA and their clinical relevance. We have critically appraised several pertinent studies on dupA and discussed their merits and shortcomings. This review also highlights dupA gene as an important biomarker for DU in certain populations.

Detection of Helicobacter pylori oipA and dupA genes among dyspeptic patients with chronic gastritis

ABSTRACT Helicobacter pylori (H. pylori) is a microbe with wide genetic diversity that infects the stomach of most people in developing countries, leading to several clinical outcomes among different individuals such as gastritis, ulcers, or gastric cancer. Outer inflammatory protein A (oipA) and duodenal ulcer promoting (dupA) genes are among the possible virulence factors which determine the patient outcome. Aim To detect oipA and dupA genes of H. pylori among dyspeptic Egyptian patients, and to investigate their correlation with the varying degrees of the associated chronic gastritis. Methods The study enrolled 50 patients with dyspepsia, attending the Gastrointestinal Endoscopy unit of the Gastroenterology and Tropical Departments at Ain Shams University Hospital for upper gastrointestinal endoscopy, in the period between, June and, December 2019. Four antral gastric biopsies were taken from each patient for polymerase chain reaction assay to detect the virulence genes oipA, dupA, and cagA and for histopathological assessment. Results Forty patients were H. pylori positive by histopathology and PCR. cagA, oipA, and dupA were identified in 6 (15%), 13 (32.5%), 9 (22.5%) of biopsies, respectively. Both cagA and oipA genes were highly significantly associated with increasing the severity of gastritis. Only oipA virulence gene showed a highly significant association with gastroduodenitis. There was a highly significant moderate association between cagA and oipA genes. Conclusion oipA could be a virulence biomarker that serves a great value in predicting the progress of gastric mucosal damage in patients with chronic gastritis, and targeting antimicrobial therapy in those patients to prevent severe gastroduodenal diseases.

Carrying a 112 bp-segment in Helicobacter pylori dupA may associate with increased risk of duodenal ulcer

The discovery of Helicobacter pylori in 1983 challenged researchers around the world to identify this pathogen's major virulence factors. The main rationale for this kind of research was to identify a biomarker associated with specific diseases following H. pylori colonization. Among different investigated virulence factors, duodenal ulcer promoting gene A (dupA) has been found to be associated with duodenal ulcer (DU), but its effect was different in various geographical regions. To determine the prevalence of dupA, we applied both classic primer pairs and our newly developed primers producing a highly conserved segment in PCR method. In our survey, 143 (47%) H. pylori isolates were obtained from 304H. pylori-colonized individuals [age range of 19–92; 113 (37%) males with the mean age of 50 and 191 (63%) females with the mean age of 49]. The presence of the dupA gene was investigated by using the different specific primers. The prevalence of the 112 bp segment isolated from H. pylori strains recovered from DU, GU and atrophy groups were significantly higher (81%, p value = .002, 64%, p = .065, 68% and p = .047 38%, respectively) than our control group, where the prevalence of the 112 bp segment was only 38%. Interestingly, a significant relationship was observed between the occurrence of DU and the presence of the 112 bp segment [p = .002; OR: 6.98; (95% CI: 1.94–25.00)]. Taken as a whole, we believe the 112 bp region of H. pylori dupA may serve as the first detected biomarker for the early detection of DU in patients admitted to hospitals.

Virulence factor genotyping of Helicobacter pylori isolated from Costa Rican dyspeptic patients

Background and aimsCosta Rica is one of the countries with the highest incidence and mortality rates for gastric cancer. Helicobacter pylori infection rates are high in the whole country. We have previously shown that H. pylori CagA+ is significantly associated with atrophic gastritis (AG) of the antrum in a dyspeptic population. The aim of this work is to determine if other H. pylori virulence factors (vacA, dupA, oipA, iceA and babA2) are associated with atrophic gastritis (AG) or duodenal ulcer (DU). MethodsThe presence of virulence genes in Costa Rican H. pylori isolates was analyzed by PCR in 151 cultured strains from patients with dyspeptic symptoms. Endoscopic and histopathological diagnoses were available. Odds-ratio and 95% confidence intervals for AG patients vs. non-atrophic gastritis (NAG) or DU patients vs. no duodenal ulcer (NDU) patients were calculated. ResultsAmongst the studied isolates, 82% had the cagA+, 76.2% had the vacA s1m1, 97.0% had the oipA+, 21.0% had the icea1, 79.0% had the iceA2, 44.0% had the babA2+ and 76.0% the dupA+ genotypes. Infection with H pylori cagA+, dupA+, oipA+, iceA, babA2+, and vacA s1m1 genotypes was not associated with AG risk. The frequency of the dupA gene was 78.7 and 60.9% in isolates from patients with NDU and DU, respectively, and its presence was significantly associated with decreased risk of duodenal ulcer [odds-ratio: 0.33, p = 0.024, confidence interval 95% (0.11–0.85)]. ConclusionH. pylori dupA genotype is inversely associated with DU risk in this population.

The Significant Association of the dupA and cagA genes of Helicobacter pylori with Peptic Ulcer

Background: Helicobacter pylori play a significant etiological role in various digestive diseases. Peptic ulcer is caused by H. pylori, which destroys the duodenum mucus and is often observed in the individuals consuming tobacco, spicy and heavy meals, alcohol, coffee, and tranquilizers. Several studies have indicated that duodenal ulcer promoting genes dupA and cagA are involved in H. pylori etiology. The present study aimed to evaluate the correlation between these genes and peptic ulcer. Methods: In this study, 500 stomach biopsy samples were assessed based on the rapid urease test and polymerase chain reaction (PCR) for H. pylori infection, followed by histological and microscopic examinations. Results: The dupA and cagA genes were subjected to PCR. Although dupA showed no significant correlation with peptic ulcer, the cagA genotype had a significant association with peptic ulcer (P less-than 0.05). Similar to the dupA gene, blood group was not observed to be correlated with H. pylori infection. Conclusion: According to the results, there are significant correlations between tobacco use (P less-than 0.05), tranquilizer use (P less-than 0.05), and meteorism (P less-than 0.05) with peptic ulcer. In addition, the expression of the cagA and dupA genes was investigated in patients with non-ulcer dyspepsia and peptic ulcer.

Rapid Detection of H. Pylori in Antral Biopsy Specimens by Amplification of a Conserved Sequence in the Dupa Gene

Helicobacter pylori (H. pylori) is a colonizer in the gastric mucosa of more than 50% of the human population. Complications due to this bacterium...

The expression of Helicobacter pylori tfs plasticity zone cluster is regulated by pH and adherence, and its composition is associated with differential gastric IL-8 secretion.

Helicobacter pylori virulence is associated with different clinical outcomes. The existence of an intact dupA gene from tfs4b cluster has been suggested as a predictor for duodenal ulcer development. However, the role of tfs plasticity zone clusters in the development of ulcers remains unclear. We studied several H. pylori strains to characterize the gene arrangement of tfs3 and tfs4 clusters and their impact in the inflammatory response by infected gastric cells. The genome of 14 H. pylori strains isolated from Western patients, pediatric (n=10) and adult (n=4), was fully sequenced using the Illumina platform MiSeq, in addition to eight pediatric strains previously sequenced. These strains were used to infect human gastric cells, and the secreted interleukin-8 (IL-8) was quantified by ELISA. The expression of virB2, dupA, virB8, virB10, and virB6 was assessed by quantitative PCR in adherent and nonadherent fractions of H. pylori during in vitro co-infection, at different pH values. We have found that cagA-positive H. pylori strains harboring a complete tfs plasticity zone cluster significantly induce increased production of IL-8 from gastric cells. We have also found that the region spanning from virB2 to virB10 genes constitutes an operon, whose expression is increased in the adherent fraction of bacteria during infection, as well as in both adherent and nonadherent fractions at acidic conditions. A complete tfs plasticity zone cluster is a virulence factor that may be important for the colonization of H. pylori and to the development of severe outcomes of the infection with cagA-positive strains.

Are non-pylori helicobacters present in the human oral cavity?

Helicobacter pylori (H. pylori) is a human gastric pathogen. Because of presence of H. pylori oral cavity, there is a possibility of H. pylori transmission by oral-oral route. In a crosssectional study, the presence of some virulence factors of H. pylori and also non-pylori Helicobacters in dental plaque samples of participants was investigated. The samples were collected from at least two teeth surfaces. DNA of the samples was extracted using specific kit. The presence of dupA (jhp0917 and jhp0918) and babA2 genes and also Helicobacter genus and H. pylori species was investigated using polymerase chain reaction by specific primers. In total 44% (20/45) and 86.7% (39/45) of samples was positive for ureC and 16SrRNA genes respectively. The frequency of babA2, jhp0917 and jhp0918 genes in H. pylori isolates were 40, 20 and 65% respectively. It seems 19 samples were positive probably non-pylori Helicobacters. In the present study we report for the first time the presence of non-pylori Helicobacter species and also high frequency of babA2 and dupA genotypes in dental plaque samples.

Association between cagA, vacAi, and dupA genes of Helicobacter pylori and gastroduodenal pathologies in Chilean patients.

In addition to the already known cagA gene, novel genetic markers have been associated with Helicobacter pylori (H. pylori) virulence: the dupA and vacAi genes. These genes might play an important role as specific markers to determine the clinical outcome of the disease, especially the vacAi gene, which has been expected to be a good marker of severe pathologies like gastric adenocarcinoma. In the present study, the association of cagA, dupA, and vacAi genes with gastroduodenal pathologies in Chilean patients was studied. One hundred and thirty-two patients positive for H. pylori were divided into two groups-non-severe and severe gastric pathologies-and investigated for the presence of cagA, dupA, and vacAi H. pylori virulence genes by PCR. The cagA gene was detected in 20/132 patients (15.2%), the vacAi1 gene was detected in 54/132 patients (40.9%), the vacAi2 gene was detected in 26/132 patients (19.7%), and the dupA gene was detected in 50/132 (37.9%) patients. Logistic regression model analysis showed that the vacAi1 isoform gene in the infected strains and the severity of the diseases outcome were highly associated, causing severe gastric damage that may lead to gastric cancer (p<0.0001; OR=8.75; 95% CI 3.54-21.64). Conversely, cagA (p=0.3507; OR=1.62; 95% CI 0.59-4.45) and vacAi2 (p=0.0114; OR=3.09; 95% CI 1.26-7.60) genes were not associated with damage, while the dupA gene was associated significantly with non-severe clinical outcome (p=0.0032; OR=0.25; 95% CI 0.09-0.65). In addition, dupA gene exerts protection against severe gastric pathologies induced by vacAi1 by delaying the outcome of the disease by approximately 20years.

Lack of association association between the presence of dupA and babA 2 genes in Helicobacter pylori and gastroduodenal disorders

Bacterial virulence factors are important in determining the outcome of H. pylori associated diseases. The initial stage of colonization is the binding of H. pylori to surface receptors on gastric epithelial cells known as bаbА. It caused colonization by another recently described H. pylori virulence factor, the duodenal ulcer promoter gene A, which is a specific marker for the development of duodenal ulcer and protection against gastric adenocarcinoma. Based on heterogeneity among H. pylori strains, this study was aimed at investigating the frequency of bаbА 2 and dupA genes in clinical isolates of H. pylori and its correlation with different H. pylori associated diseases in Kermanshah, Iran. Stomach biopsy specimens were collected and inoculated into egg yolk and antibiotics supplemented Columbia agar. Presumptive colonies were confirmed biochemically and genetically, and the presence of bаbА 2 and dupA genes was detected by PCR. This study included a total of 96 isolates from patients with different gastroduodenal disorders. The prevalence of bаbА 2 and dupA genes was observed to be 58.38 and 37.5%, respectively. Despite the fact that there was no statistically significant relationship between bаbА 2 and dupA virulence factors and gastroduodenal diseases, a high frequency of the genes was recorded among the isolates in Iran.

The study of the oipA and dupA genes in Helicobacter pylori strains and their relationship with different gastroduodenal diseases.

The purpose of this investigation was to determine the oipA and dupA genes of Helicobacter pylori isolates from west of Iran; Chaharmahalo Bakhtiyari region and find their relationship with the severity of the gastroduodenal diseases. Helicobacter pylori is an organism responsible for many gastroduodenal diseases. Many studies suggest that genetic diversity in H . pylori virulence factors such as oipA and dupA genes is high among isolates of different geographic regions and may cause more severe diseases. In this cross-sectional study, gastric biopsy specimens were taken from 150 patients suffering from gastroduodenal diseases. The presence of ureC, dupA and oipA genes was tested by polymerase chain reaction (PCR). Overall, 123 (82%) H. pylori strains were isolated from 150 specimens. dupA gene was detected in 41 (33.33%) H.pylori-positive specimens. There was a reverse correlation between this gene and gastric cancer. The oipA gene was found in 88 (71.54%) samples and statistically there was no association between this gene and gastric disorders. As statistical analyses revealed, the presence of the dupA was more common in isolates with the oipA negative. Based on our findings, the presence of dupA gene can be considered as a marker for the onset of severe diseases. However, the oipA gene cannot be regarded for prediction of gastroenterology diseases. Meanwhile, extended molecular epidemiology researches in other populations are recommended.

Different distribution of Helicobacter pylori EPIYA- cagA motifs and dupA genes in the upper gastrointestinal diseases and correlation with clinical outcomes in iranian patients.

Our aim was to determine the EPIYA-cagA Phosphorylation sites and dupA gene in H. pylori isolates among patients with upper gastrointestinal diseases. Pathogenicity of the cagA-positive Helicobacter pylori is associated with EPIYA motifs and higher number of EPIYA-C segments is a risk factor of gastric cancer, while duodenal ulcer-promoting gene (dupA) is determined as a protective factor against gastric cancer. A total of 280 non-repeated gastric biopsies obtained from patients undergoing endoscopy from January 2013 till July 2013. Samples were cultured on selective horse blood agar and incubated in microaerophilic atmosphere. The isolated organisms were identified as H. pylori by Gram staining and positive oxidase, catalase, and urease tests. Various motif types of cagA and the prevalence of dupA were determined by PCR method. Out of 280 specimens, 128 (54.7%) isolated organisms were identified as H. pylori. Of 120 H. pylori isolates, 35.9% were dupA positive and 56.26% were cagA positive, while cagA with ABC and ABCC motifs were 55.5% and 44.5%, respectively. Fifty six percent of the isolates with the ABCC motif have had dupA genes. We also found a significant association between strains with genotypes of dupA-ABC and duodenal ulcer disease (p = 0.007). The results of this study showed that the prevalence of cagA-positive H. pylori in Shiraz was as high as in western countries and higher numbers of EPIYA-C segments were seen in gastric cancer patients. We may also use dupA as a prognostic and pathogenic marker for duodenal ulcer disease and cagA with the segment C for gastric cancer and gastric ulcer disease in this region.

Prevalence of Helicobacter pylori cagA, babA2, and dupA genotypes and correlation with clinical outcome in Malaysian patients with dyspepsia.

The severity of disease outcome in dyspepsia has been attributed to Helicobacter pylori virulence genes. The aim of this study was to determine the distribution of H. pylori virulence genes (cagA, babA2, and dupA) and to determine whether or not there arises a significant correlation with clinical dyspepsia outcomes. H. pylori genotypes cagA, babA2, and dupA were identified by polymerase chain reactions from gastric biopsy samples in 105 H. pylori-positive patients. The positive rates for cagA, babA2, and dupA genes in H. pylori dyspeptic patients were 69.5%, 41.0%, and 22.9%, respectivel cagA was more prevalent in Indians (39.7%), babA2 was more prevalent in Malays (39.5%), and dupA detection occurred more frequently in both Indians and Malays and at the same rate (37.5%). The Chinese inhabitants had the lowest prevalence of the three genes. Nonulcer disease patients had a significantly higher distribution of cagA (76.7%), babA2 (74.4%), and dupA (75.0%). There was no apparent association between these virulence genes and the clinical outcomes. The lower prevalence of these genes and variations among different ethnicities implies that the strains are geographically and ethnically dependent. None of the virulence genes were knowingly beneficial in predicting the clinical outcome of H. pylori infection in our subjects.

Detection of the Helicobacter pylori dupA gene is strongly affected by the PCR design

The Helicobacter pylori virulence gene dupA is usually detected by PCR, but the primer binding sites used are highly variable. Our newly designed qPCR against a conserved region of dupA was positive in 64.2% of 394 clinical isolates while the positivity rate of the commonly used PCRs ranged from 29.9% to 37.8%.

Association among H. pylori virulence markers dupA, cagA and vacA in Brazilian patients

BackgroundOnly a few Helicobacter pylori-infected individuals develop severe gastric diseases and virulence factors of H. pylori appear to be involved in such clinical outcomes. Duodenal ulcer promoting gene A (dupA) is a novel virulence factor of Helicobacter pylori that is associated with duodenal ulcer development and reduced risk for gastric carcinoma in some populations. The aims of the present study were to determine the presence of dupA gene and evaluate the association among dupA and other virulence factors including cagA and vacA in Brazilian patients. Gastric biopsies were obtained from 205 dyspeptic patients (100 children and 105 adults). DNA was extracted and analyzed for the presence of H. pylori and its virulence factors using the polymerase chain reaction method.ResultsPatients with gastritis tested positive for H. pylori more frequently. The dupA gene was detected in 41.5% of them (85/205); cagA gene was found in 98 isolates (47.8%) and vacA genotype s1/m1 in 50.2%, s1/m2 in 8.3%, s2/m2 in 36.6%, s2/m1 in 0.5% and s1/s2/m1/m2 in 4.4%. We also verified a significant association between cagA and dupA genes [p = 0.0003, relative risk (RR) 1.73 and confidence interval [CI] = 1.3–2.3]. The genotypes s1/m1 were also associated with dupA gene (p = 0.0001, RR: 1.72 and CI: 1.3–2.2). The same associations were found when analyzing pediatric and adult groups of patients individually.ConclusionOurs results suggest that dupA is highly frequent in Brazilian patients and is associated with cagA gene and vacA s1/m1 genotype, and it may be considered an important virulence factor in the development of gastric diseases in adults or children.