cagA, vacA and iceA Virulence Genes of Helicobacter pylori Isolates of Children in Finland

 cagA, vacA s and m genotypes and iceA alleles were analyzed from Helicobacter pylori strains isolated from 17 Finnish children and 32 children of non-Finnish origin living in Finland. Twelve children in the latter group were eastern European and 15 were of African origin. Only three children of non-Finnish origin were born in Finland. The vacA s1a subtype was more prevalent in the isolates from Finnish children than African children (76% vs. 7%, P<0.001);vacA s1b frequencies were 5% and 67%, respectively (P<0.001). The iceA1 allele was significantly more prevalent in African than Finnish isolates (93% vs. 35%, P<0.01). Considerable variation was noted in the frequency of vacA s1 subtypes and iceA alleles in children originating from different geographic regions, but the geographic variation of s1 subtypes resembled that described in other reports.     

Clinical Relevance of the vacA, iceA, cagA, and flaA genes of Helicobacter pylori strains isolated in Eastern Taiwan

The genotypes of Helicobacter pylori flaA, cagA, vacA, and iceA were determined for DNA isolated from patients with chronic gastritis or peptic ulcer in eastern Taiwan. The vacA gene encoding the s1a subtype was found to predominate in peptic ulcer patients, and the iceA1 genotype was associated with chronic gastritis. cagA and flaA genes were not found to be associated with these types of disease.     

Prevalence of Helicobacter pylori vacA,cagA and iceA genotypes in Nigerian patients with duodenal ulcer disease

Distinct virulence factors of Helicobacter pylori have been associated with clinical outcome of the infection; however, considerable variations have been reported from different geographic regions. Data on genotypes of African H. pylori isolates are sparse. The aim of this study was to determine the prevalence of specific genotypes of H. pylori in Nigerian patients with duodenal ulcer and non-ulcer dyspepsia. H. pylori was cultured from endoscopic biopsies obtained from 41 Nigerian patients (19 with duodenal ulcer, 22 with non-ulcer dyspepsia). The vacA alleles, cagA and iceA genotypes were determined by PCR. The vacA s1,m1 and s1,m2 genotypes were found in 26.3% and 22.7%, and in 73.7% and 72.7% of H. pylori isolates from patients with duodenal ulcer and non-ulcer dyspepsia, respectively. The iceA1 genotype was present in 94.7% and 86.4% of isolates from duodenal ulcer and non-ulcer dyspepsia patients, respectively. cagA+ infection was found predominantly (> 90%) in Nigerian H. pylori isolates irrespective of the clinical diagnosis. In conclusion, vacA s1,m2, iceA1 and cagA+ are common genotypes of H. pylori isolated from Nigerian patients. As in several other developing countries there seems to be no association between these genotypes and duodenal ulcer disease.     

Helicobacter pylori cagA, vacA and iceA genotypes in western Indian population of Maharashtra with varied gastroduodenal diseases

Scarce reports relying on rapid urease test, serology and histopathology are currently known for H. pylori from Western India, Maharashtra. We investigated H. pylori genotypes at molecular level in gastro-duodenal disease population during the years 2002-2005. H. pylori presence was scored by polymerase chain reaction in the infected biopsies (n = 95) in various gastric diseases. H. pylori specific 16S rDNA gene amplification based preliminary identification coupled with protein coding gene amplification scores were assessed for the incidence. H. pylori 16S rDNA and 7 housekeeping genes were detected in all biopsies, whereas 71.18% and 28% found to be cagA positive and negative respectively. The vacA toxigenic alleles (vacA s1) and middle region subunit vac m1a were found in 54%, and 59% patients. However, the iceA1 was present in 40.06%; the iceA2 was less i.e. in 13.5% patients. The most common allelic combinations in different age groups irrespective of disease types were 13-30, 31-45, 46-60 and 61-73 were cagA-vac m1a-vacA s1-iceA1. In our analysis, PCR was found to be 100% accurate in detecting H. pylori in gastric biopsies. Among West Indian population H. pylori was found to be present, irrespective of any correlation with the genotype and gender of patients with the clinical outcome. However, the genotype incidences were related to age of the patients, wherein the age group ranging from 46 to 60 years was found be susceptible for H. pylori infection.     

Helicobacter pylori cagA and vacA cytotoxin genes in Changsha,China

Cytotoxin-associated protein (cagA) and the vacuolating cytotoxin (vacA) encoded by cagA and vacA genes are virulence determinants of Helicobacter pylori. In earlier studies among Chinese patients, all H. pylori strains were cagA-positive and vacAs1a/m2 type. Here, we determine the cagA, vacA and allele status of H. pylori strains isolated from patients with upper gastrointestinal symptoms in Changsha, China. Forty strains of H. pylori isolated from patients with peptic ulcer disease between March 1997 and August 1999 were recovered from storage at -80 degrees C and studied by the polymerase chain reaction (PCR) for cagA and vacA genotypes. cagA was positive in 75% of H. pylori isolates. Patients with peptic ulcer demonstrated cagA in 83% (15/18), compared with 68% (15/22) patients with superficial gastritis. vacAs1 allele was carried in 82.5% (33/40) isolates, of which 52.5% (21/40) were subtype vacAs1a/m2 and 17.5% (7/40) were subtype vacAs1b/m2.     

Clinical and histological associations of cagA and vacA genotypes in Helicobacter pylori gastritis.

AIMS: To determine the relation among the cytotoxin associated gene (cagA) and vacuolating cytotoxin gene (vacA) status of Helicobacter pylori isolates, the associated clinical diseases, and the severity and pattern of chronic gastritis. METHODS: Helicobacter pylori was cultured from gastric biopsies obtained from dyspeptic patients. DNA was extracted from the isolates and the cagA and vacA status determined by the polymerase chain reaction (PCR). The prevalence of the different cagA and vacA genotypes in three clinical groups, duodenal ulcer, gastric ulcer, and non-ulcer dyspepsia was compared. The histological features in sections from two antral and two corpus biopsies were graded by one blinded observer. The grades were compared with age and sex matched groups with different cagA and vacA genotypes, and with duodenal ulcers, or non-ulcer dyspepsia. RESULTS: Isolates from 161 patients were included. One hundred and nine (68%) harboured a cagA+ strain and 143 (89%) harboured a vacA s1 strain. The prevalence of cagA+ strains in duodenal ulcer patients (94%) was highly significantly greater than in those with non-ulcer dyspepsia (56%). However, of the patients infected with a cagA+ strain, almost equal numbers had non-ulcer dyspepsia or peptic ulceration. Chronic inflammation, polymorph activity, surface epithelial degeneration, atrophy, and intestinal metaplasia were all significantly more severe in the cagA+ than in the cagA- group, whereas only corpus epithelial degeneration was significantly more severe in the vacA s1 group compared with the vacA s2 group. Patients infected with cagA+ strains were almost four times more likely to have antral intestinal metaplasia than cagA- patients. An antral predominant gastritis was present in duodenal ulcer patients compared with matched non-ulcer dyspepsia patients, but this was not attributable to cagA or vacA status. CONCLUSIONS: Helicobacter pylori strains showing cagA positively and the vacA s1 genotype are associated with more severe gastritis but these virulence factors do not appear to determine the overall pattern. The pattern is closely linked to clinical disease. Therefore, it is likely that the nature of the disease complicating chronic infection is determined by host and environmental factors, while bacterial factors determine the magnitude of the risk of developing such disease.     

High Prevalence of Clarithromycin Resistance and cagA,vacA, iceA2, and babA2 Genotypes of Helicobacter pylori in Brazilian Children

We isolated 45 Helicobacter pylori strains from 217 child patients. Resistance to clarithromycin, metronidazole, amoxicillin, and tetracycline was detected in 27%, 13%, 4%, and 0% of strains, respectively. The A2143G mutation was the most prevalent (67%) among clarithromycin-resistant strains. In addition, strain genotyping revealed a significant association between gastritis severity and the simultaneous presence of cagA, vacA s1m1, iceA2, and babA2 genes.Helicobacter pylori infection is found worldwide and constitutes a public health concern in many countries. Previous epidemiological studies have shown a high prevalence of H. pylori infection in Brazil (2, 20, 24). H. pylori infection, generally acquired in childhood, persists asymptomatically for decades in most individuals.Amoxicillin, tetracycline, metronidazole, and clarithromycin are frequently used, combined with proton pump inhibitors or bismuth salts, for the treatment of H. pylori infections (25). However, antibiotic resistance is frequently associated with eradication failure (3, 16). Resistance to metronidazole and clarithromycin is population dependent, and several studies suggest that clarithromycin resistance is higher in strains isolated from children than in strains isolated from adults (10). In Brazil, the prevalence of clarithromycin-resistant strains in adults is reported to be from 7 to 10% (15, 18). However, little is known about the prevalence of clarithromycin-resistant H. pylori infection in Brazilian children.The primary aims of this study were to determine the prevalence of clarithromycin-resistant H. pylori strains in children, to identify those isolates via rapid methodology, and to examine the severity of gastritis caused by the antibiotic-resistant H. pylori isolates. Metronidazole, amoxicillin, and tetracycline resistance was also studied. Furthermore, the study aimed to genotype the vacA and iceA genes and to detect the cagA gene in gastric biopsy specimens, since recent studies found a high frequency of cagA-positive and iceA2-positive strains as well as a strain with the vacA signal region genotype s1 and middle region sequence m1 among pediatric H. pylori isolates in Brazil (6, 7, 11, 23). This is also the first investigation of babA2 gene prevalence in Brazilian children.A total of 217 consecutive child patients, aged 1 to 18 years (mean age, 10 years) (105 girls and 112 boys), who underwent upper gastrointestinal endoscopy for the evaluation of dyspeptic symptoms at the outpatient clinic of Pediatric Gastroenterology at the Instituto da Criança, Faculdade de Medicina da Universidade de São Paulo, during 2008 and 2009 were included. The study was approved by the Ethics Committee of the University Hospital. Patients previously treated for H. pylori infections were not included.Gastric biopsy specimens were processed for histological examination and evaluated according to the updated Sydney system of classification and grading of gastritis (4).Antral gastric specimens were transported in sodium thioglycolate broth (Difco, Detroit, MI) in an ice bath and ground before submission to DNA extraction and PCR-restriction fragment length polymorphism (PCR-RFLP) analysis with primers specific to the H. pylori 23S rRNA gene (17). The QIAmp tissue kit (Qiagen) was used for DNA extraction. Point mutations related to clarithromycin resistance in the 23S rRNA amplicon were investigated in all H. pylori isolates by PCR-RFLP using BsaI and MboII enzymes (27). The vacA, cagA, iceA, and babA2 genotypes were detected by PCR, as described elsewhere (1, 9, 21, 26, 28). In each experiment, H. pylori strain 26695 (ATCC 700392) was used as the positive-control strain.H. pylori strains were cultured on Belo Horizonte medium (22) under microaerophilic atmosphere at 37°C for 3 to 7 days, and the isolates were identified by Gram staining and biochemical tests for oxidase, catalase, and urease production. Resistance to clarithromycin, metronidazole, amoxicillin, and tetracycline was determined by the disc diffusion method (Oxoid), and MICs were determined by the Etest according to the manufacturer''s recommendations (AB Biodisk, Solna, Sweden). An isolate was considered resistant to clarithromycin or tetracycline if the MIC was >1 mg/liter and to metronidazole or amoxicillin if the MIC was >4 mg/liter (19).Data were analyzed by the two-tailed χ² test and Fisher exact test. P values of <0.05 were considered statistically significant.H. pylori was isolated in 45 (20.7%) of the 217 children; 12 (26.7%) of the 45 strains were clarithromycin resistant, 6 (13.3%) were metronidazole resistant, and 2 (4.4%) were amoxicillin resistant. All cultured H. pylori strains were susceptible to tetracycline (Fig. ​(Fig.1).1). No histological differences were observed between biopsy specimens with antibiotic-resistant strains and those with susceptible strains. PCR-RFLP was performed with all 12 clarithromycin-resistant isolates: 8 had the 23S rRNA A2143G point mutation, and 4 had the 23S rRNA A2142G mutation.Open in a separate windowFIG. 1.Distribution of MICs for the 45 H. pylori strains.Among the 45 H. pylori-infected children, 13 had mild chronic gastritis, 28 had moderate chronic gastritis, 2 had marked chronic gastritis, and 2 had normal gastric mucosa. The percentage of H. pylori-infected children with chronic gastritis was 95.5% (43 patients), while 4.4% of the children (2 patients) had normal mucosa (P < 0.001).vacA was detected in all 45 H. pylori-positive gastric biopsy specimens. The vacA genotypes s1m1, s2m2, and s1m2 or s2m1 were found in 57.7, 33.3, and 4.4% of the specimens, respectively. The iceA1 allele was detected in 9 (20%) and the iceA2 allele in 31 (68.9%) of the samples. Of the 45 H. pylori-positive biopsy specimens, 28 (62%) were cagA positive and 38 (84.4%) were babA2 positive. Correlation of histopathology results with vacA, cagA, and iceA genotypes showed that vacA s1m1-, cagA-, and iceA2-positive strains were more frequently found in patients with moderate and marked gastritis (77%) than in patients with mild gastritis (23%) (P < 0.001). Interestingly, in Slovenian children, vacA s1 and cagA were also shown to be associated with more pronounced chronic gastritis (12). In contrast, in Korean children, although vacA s1m1 cagA iceA1 was the predominant genotype, no association with gastritis severity was observed (14).In conclusion, we found a high incidence of clarithromycin-resistant H. pylori strains (27%) in Brazilian children. Furthermore, we found an association between clarithromycin resistance and either the vacA s1m1 (P = 0.007) or the iceA2 (P = 0.038) genotype. The high level of clarithromycin resistance among strains from children compared to adults (15, 18) suggests the importance of susceptibility testing, especially in Brazilian children. All together, these data stress the relevance of susceptibility testing and genotyping for establishing antibiotic treatment in pediatric H. pylori infection.In our study, PCR-RFLP proved to be a rapid and accurate method for the detection of clarithromycin resistance gene mutation directly in gastric biopsy samples. Only a few groups have studied mutations involved in clarithromycin resistance in strains obtained from children, and their results are similar to those obtained in our study (5, 13, 29).Our data also demonstrate an association between H. pylori infection and gastritis in Brazilian children. In addition, we confirmed the reported association of infection with vacA s1m1 cagA iceA2-positive H. pylori strains and gastritis severity (6, 11, 23). Furthermore, a high frequency of babA2 was found among H. pylori isolates. Previous studies of adults in Brazil reported a high prevalence of babA2-positive strains from patients with different upper gastrointestinal diseases (8). The high incidence of babA2 in H. pylori Brazilian isolates suggests that this gene could be a useful marker for identifying patients with a high risk of H. pylori infection in Brazil.     

Colonization of Mexican Patients by Multiple Helicobacter pylori Strains with Different vacA and cagA Genotypes

Helicobacter pylori virulence determinants have not previously been studied in detail in Latin Americans with H. pylori infections. We characterized the vacA (vacuolating cytotoxin gene A) and cagA (cytotoxin-associated gene A) types of more than 400 single-colony isolates from 20 patients in Mexico City. For 17 patients H. pylori strains of two or more different vacA genotypes were isolated from gastric biopsy specimens, indicating infection with two or more strains of H. pylori. The most frequent vacA genotype was s1b/m1. vacA diversity was more marked than that described previously, in that isolates from seven patients had untypeable vacA midregions and isolates from nine patients had type s1 signal sequence coding regions which could not be further subtyped. Previously undescribed vacA type s2/m1 strains were found in five patients. All patients were infected with cagA-positive strains, but occasionally, these coexisted with small numbers of cagA-negative strains. In conclusion, coinfection with multiple H. pylori strains is common in Mexico, and vacA in these strains is genetically more diverse than has been described in other populations.     

Clinical relevance of cagA and vacA gene polymorphisms in Helicobacter pylori isolates from Senegalese patients

The molecular epidemiology of Helicobacter pylori in Africa is poorly documented. From January 2007 to December 2008, we investigated 187 patients with gastric symptoms in one of the main tertiary hospitals in Dakar, Senegal. One hundred and seventeen patients were culture-positive for H. pylori. Polymorphisms in vacA and cagA status were investigated by PCR; the 3′-region of cagA was sequenced, and EPIYA motifs were identified. Bacterial heterogeneity within individuals was extensively assessed by using an approach based on vacA and cagA heterogeneity. Fourteen per cent of H. pylori-positive patients displayed evidence of mixed infection, which may affect disease outcome. Patients with multiple vacA alleles were excluded from subsequent analyses. Among the final study population of 105 patients, 29 had gastritis only, 61 had ulcerated lesions, and 15 had suspicion of neoplasia based on endoscopic findings. All cases of suspected neoplasia were histologically confirmed as gastric cancer (GC). The cagA gene was present in 73.3% of isolates. CagA proteins contained zero (3.7%), one (93.9%) or two (2.4%) EPIYA-C segments, and all were western CagA. Most of the isolates possessed presumed high-vacuolization isotypes (s1i1m1 (57.1%) or s1i1m2 (21.9%)). Despite the small number of cases, GC was associated with cagA (p 0.03), two EPIYA-C segments in the C-terminal region of CagA (p 0.03), and the s1 vacA allele (p 0.002). Multiple EPIYA-C segments were less frequent than reported in other countries, possibly contributing to the low incidence of GC in Senegal.     

Correlation between IL-8 induction, cagA status and vacA genotypes in 153 French Helicobacter pylori isolates

The polymorphism of clinical presentations associated with Helicobacter pylori infection is potentially due to differences in the virulence of individual strains. H. pylori virulence has been associated with the ability to induce secretion of interleukin-8 (IL-8), the vacA genotypes, and the cagA status. The aim of this study was to determine the virulence profiles of 153 French H. pylori isolates on the basis of vacA genotypes, cagA status, and IL-8 induction ability. A total of 153 H. pylori isolates from patients with chronic gastritis (n = 74) or gastro-duodenal ulcers (n = 79) was examined for vacA genotypes and cagA status by polymerase chain reaction (PCR) and dot blot, and for their ability to induce IL-8 secretion by HEp-2 cells. The prevalence of vacA genotypes was: s1/m1 44.3%, s1/m2 24.9%, and s2/m2 23.5%. The cagA gene was present in 64% of the strains. IL-8 secretion was induced by 58.7% of the isolates. The presence of the cagA gene was significantly correlated with the s1/m1 vacA genotype and with the induction of IL-8. Thirty-four strains were atypical (cagA-positive/IL-8 noninducer or cagA-negative/IL-8 inducer). vacA genotypes, cagA status, and IL-8 induction ability are not correlated with the presence or absence of ulcer. The cagA status is not sufficient to predict the proinflammatory ability of H. pylori.     

Prevalence of Helicobacter pylori vacA and cagA genotypes in Ethiopian dyspeptic patients

A total of 300 gastric biopsy samples and 50 Helicobacter pylori isolates were collected from Ethiopian adult dyspeptic patients. The vacA and cagA genes were detected in 90 and 79% of biopsy specimens, respectively, and in 100 and 87% of clinical isolates, respectively. Both genes were detected in 84% of the gastric biopsy samples and in 87% of the clinical isolates. Among vacA genotypes, the s1/m1 genotype was the most common in gastric biopsy samples (48%). The vacA and cagA positive H. pylori strains were detected to a higher degree in patients with chronic active gastritis (71%) than patients with other histopathological findings (29%) (P < 0.05).     

The efficacy of laboratory diagnosis of Helicobacter pylori infections in gastric biopsy specimens is related to bacterial density and vacA, cagA, and iceA genotypes

A total of 500 consecutive patients undergoing upper endoscopy were biopsied and tested for H. pylori infection by the Campylobacter-like organism (CLO) test, culture, histology, and PCR. Serum samples were tested by two different serological assays. Patients were considered H. pylori positive if at least two of the four biopsy specimen-based methods yielded positive results. PCR had the highest diagnostic sensitivity (99.4%), followed by histology (92.2%), culture (89.5%), and the CLO test (89.0%). The specificities of all methods were higher than 98%. Of the organisms from the 181 PCR-positive patients, the vacA (s and m regions), cagA, and iceA genotypes were determined by reverse hybridization (line probe assay) or an allele-specific PCR. Organisms that were detected by PCR but that remained undetected by the CLO test were significantly more often vacA s1 (P = 0.006), m1 (P = 0.028), and cagA positive (P = 0.029) than vacA s2, m2, and cagA negative, respectively. Organisms that were detected by PCR but that remained undetected by culture or histology more often contained iceA1 (P = 0. 034 and P = 0.029, respectively) than iceA2. Higher H. pylori density was associated with vacA s2 (P = 0.024), vacA m2 (P = 0.050), and cagA-negative (P = 0.035) genotypes. Also, the diagnostic results of the CLO test (P = 0.001) and culture (P = 0.031) but not those of the PCR (P = 0.130) were significantly associated with the H. pylori density. The rate of detection by the four biopsy specimen-based tests was lower for patients who used proton pump inhibitors, but this was independent of the H. pylori genotypes. These observations may be explained by different bacterial densities, as established by the distinct genotypes of H. pylori, and confirm that the biologies of strains with such genotypes are considerably different.     

Assessment of Helicobacter pylori vacA and cagA genotypes and host serological response

Helicobacter pylori strains can be distinguished by genotyping of virulence-associated genes, such as vacA and cagA. Because serological discrimination between strain types would reduce the need for endoscopy, 61 patients carrying H. pylori were studied by vacA and cagA genotyping of H. pylori in gastric biopsy specimens and by detection of specific serum antibodies. Serological responses to H. pylori were determined by Helicoblot (versions 2.0 and 2.1). Antibodies to CagA also were determined by a rapid anti-CagA assay (Pyloriset screen CagA) as well as by two noncommercially developed enzyme immunoassays, each using a recombinant CagA protein. Assessment of performance of the Helicoblot assays indicated substantial interobserver variation, with kappa values between 0.20 and 0.93. There was no relationship between the serological profiles on the Helicoblot and the genotypes from the same patients, except for strong associations between the presence of anti-CagA and the cagA-positive and vacA s1 H. pylori genotypes. Detection of anti-CagA by the five different assays varied considerably, with kappa values ranging from 0.21 to 0.78. Using the cagA genotype as the "gold standard," the sensitivity and specificity of the anti-CagA assays varied from 71.4 to 85.7% and from 54.2 to 100%, respectively. Thus, serological profiles of antibodies to H. pylori are heterogeneous and, with the exception of anti-CagA antibodies, show no relation to the H. pylori vacA and cagA genotypes. Detection of anti-CagA antibodies is strongly dependent on the test used.     

Association of cagA and vacA Genotypes of Helicobacter pylori with Gastric Diseases in Estonia

Gastric biopsy specimens from 156 adult patients from southern Estonia suffering from chronic gastritis, peptic ulcer disease, and perforated peptic ulcer were analyzed by PCR. The cagA gene was evenly distributed throughout 87% of the specimens from the patients with the different gastric diseases. The presence of the cagA gene correlated with that of vacA signal sequence type s1a (99%). However, no clear differences were found in the distribution of cagA and vacA genotypes among patients in Estonia with severe perforated peptic ulcer, uncomplicated peptic ulcer, or chronic gastritis.     

Relationship between bacterial load,morbidity and cagA gene in patients infected by Helicobacter pylori

One hundred and seventy-six biopsies of the gastric corpus and antrum from 97 patients were processed using classical and molecular methods in order to study the relationship between the factor cagA of Helicobacter pylori, bacterial load and morbidity. Bacterial load in patients with cagA was greater than in patients without it, both in the antrum and corpus (p < 0.01). There was a statistically significant association between cagA and consumption of proton pump inhibitors (adjusted odds ratio 3.11). Haemorrhage of the upper digestive tract was more associated with bacterial load than with the cagA gene (adjusted odds ratio 2.34 and 1.12, respectively), but none of these associations yielded statistical significance.     

Helicobacter pylori babA2, cagA,and s1 vacA genes work synergistically in causing intestinal metaplasia

AIMS: To determine any associations between the Helicobacter pylori genes babA2, oipA, cagA and the s and m alleles of vacA. In addition, to verify whether these genes work synergistically or independently in causing gastritis, peptic ulcer, and intestinal metaplasia. METHODS: One hundred and sixty seven H pylori positive patients were studied (52 antral gastritis, 41 diffuse gastritis, 41 peptic ulcer, and 33 duodenitis). Helicobacter pylori virulence genes were amplified by means of the polymerase chain reaction. RESULTS: Significant associations were found between babA2 and the other H pylori genes studied. When considered singly, all the genes were associated with disease diagnosis, inflammation, and intestinal metaplasia. Four H pylori groups were defined. Group A: cagA-, s2m2, babA2-; group B: cagA+, s1m1, babA2+; group C: cagA+, s1m2, babA2+; group D: cagA+, s1m2, babA2-. Group A infecting strains were associated with less severe endoscopic and inflammatory conditions, whereas group B strains were associated with the worst endoscopic and inflammatory findings. Intestinal metaplasia was a rare finding in group A infected patients (< 10%), whereas it was frequent in those infected with group B strains (48%). CONCLUSIONS: The H pylori genes cagA, oipA "on", s1 and m1 vacA, and babA2 are associated with each other, possibly as a result of shared selective pressure. When coexpressed by the same H pylori strain, cagA, s1 and m1 vacA, and babA2 work synergistically in worsening inflammation. Infections caused by strains coexpressing cagA, s1m1 vacA, and babA2 are those at higher risk for intestinal metaplasia.     

Diversity of Helicobacter pylori vacA and cagA Genes and Relationship to VacA and CagA Protein Expression, Cytotoxin Production, and Associated Diseases

The vacuolating cytotoxin and the cytotoxin-associated protein, encoded by vacA and cagA, respectively, are important virulence determinants of Helicobacter pylori. Sixty-five H. pylori strains were isolated from dyspeptic patients (19 with peptic ulcer disease, 43 with chronic gastritis, and 3 with gastric cancer) and studied for differences in the vacA and cagA genes and their relationship to VacA and CagA expression, cytotoxin activity, and the clinical outcome of infection. By PCR, fifty-four (83.1%) of 65 strains had the vacA signal sequence genotype s1 and only 10 (15.4%) had the type s2. After primer modification, the vacA middle-region types m1 and m2 were detected in 24 (36.9%) and 41 (63.1%) strains, respectively. The combinations s1-m2 (31 [47.7%]) and s1-m1 (23 [35.4%]) occurred more frequently than s2-m2 (10 [15.4%]) (P = 0.01). No strain with the combination s2-m1 was found. All 19 patients with peptic ulcers harbored type s1 strains, in contrast to 32 (74.4%) of 43 patients with gastritis (P = 0.02). The vacA genotype s1 was associated with the presence of cagA (P < 0.0001), VacA expression (P < 0.0001), and cytotoxin activity (P = 0.003). The cagA gene was detectable in 48 (73.8%) of 65 isolates and present in 16 (84.2%) of 19 ulcer patients and 29 (67.4%) of 43 patients with gastritis (P = 0.17). The vacA genotypes of German H. pylori isolates are identical to those previously reported. H. pylori strains of vacA type s1 are associated with the occurrence of peptic ulceration and the presence of cagA, cytotoxin activity, and VacA expression.     

Distinct diversity of vacA, cagA, and cagE genes of Helicobacter pylori associated with peptic ulcer in Japan

Colonization of the stomach mucosa by Helicobacter pylori is a major cause of acute and chronic gastric pathologies in humans. Several H. pylori virulence genes that may play a role in its pathogenicity have been identified. The most important determinants are vacA and cagA in the cag pathogenicity island (cagPAI) genes. In the present study, to consider the association of molecular genetics between vacA and the cagPAI regarding clinical outcome, we selected H. pylori strains with various genotypes of vacA in Japan and sequenced full-length vacA, cagA, and cagE genes. Sequencing of vacA and cagA genes revealed variable size, whereas the cagE gene was well conserved among strains. Each of the phylogenetic trees based on the deduced amino acid sequences of VacA, CagA, and CagE indicated that all three proteins were divided into two major groups, a Western group and an East Asian group, and the distributions of isolates exhibited similar patterns among the three proteins. The strains with s2 and s1a/m1a vacA genotypes and the Western-type 3' region cagA genotype were classified into the Western group, and the strains with the s1c/m1b vacA genotype and the East Asian-type 3' cagA genotype were included in the East Asian group. In addition, the prevalence of infection with the Western group strain was significantly higher in patients with peptic ulcer (90.0%, 9/10) than in patients with chronic gastritis (22.7%, 5/22) (chi2 = 12.64, P = 0.00057). These data suggest that the molecular genetics of vacA and cagPAI are associated and that the Western group with vacA and cagPAI genes is associated with peptic ulcer disease.