Original article
Helicobacter pylori BabA Expression, Gastric Mucosal Injury, and Clinical Outcome

https://doi.org/10.1016/j.cgh.2006.09.015Get rights and content

Background & Aims: The blood grou Methods: We compared the ability of published PCR-based methods to assess BabA status with BabA immunoblotting and Lewis b (Leb) binding activity assays. We also used immunoblotting to examine the relationship between clinical presentation and levels of BabA expression. Results: Immunoblotting and Leb binding assays for 80 strains revealed 3 levels of BabA expression: BabA high producers (BabA-H) with Leb binding activity, BabA low producers (BabA-L) without Leb binding activity, and BabA-negative. BabA-negative strains lacked the babA gene. PCR methods to determine BabA status yielded poor results. babA1 sequences were never detected. BabA expression was examined in 250 strains from Western countries and 270 strains from East Asia. The results failed to confirm any relationship between triple-positive status (cagA-positive/vacA s1/BabA-H) and clinical outcome. BabA-negative strains typically were cagA-negative/vacA s2 and were associated with gastritis. BabA-L strains showed a higher level of mucosal injury and were associated more frequently with duodenal ulcer and gastric cancer than the other groups. Conclusions: Information gained from currently used PCR-based methods must be interpreted with caution. Leb binding activity does not accurately reflect the severity of mucosal damage or the clinical outcome. Quantitation of BabA expression revealed that Leb-nonbinding BabA-L strains are associated with higher levels of mucosal injury and clinical outcome.

Section snippets

Helicobacter pylori

We examined H pylori isolates cultured from patients in East Asia and North and South America with clinical presentations including simple H pylori gastritis, duodenal ulcer (DU), and noncardiac gastric adenocarcinoma. Ulcers were defined endoscopically, and patients with either ulcer scars or DU and gastric ulcers were excluded. Gastritis was defined as histologic gastritis with no peptic ulcers or gastric cancer. No patients received treatment for their H pylori infection, and those patients

Lewis b Antigen Binding Assay

We first evaluated the accuracy of assessing BabA status by immunoblotting and PCR analysis as compared with assessing Leb binding activity. Eighty H pylori strains from our Colombian and Japanese H pylori stocks (40 strains from each country) were examined. Leb binding activity was detectable in 68 (85%) of these strains (83% of the Colombian strains and 88% of the Japanese strains).

Comparison Between BabA Immunoblotting and Lewis b Antigen Binding Assay

Based on the results of immunoblotting analyses, the H pylori strains were divided into 2 major groups: BabA

Discussion

We show that PCR-based methods designed to detect a 10-bp deletion in the signal region of the babA gene do not reliably reflect BabA expression as determined by immunoblotting or Leb binding activity. These results call into question the conclusions of previous studies using those techniques to relate BabA functional status and histology or clinical outcome.

BabA-negative status is associated with mild gastric injury and lower H pylori density. BabA-negative strains also are associated

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    This report is based on work supported in part by grants from the National Institutes of Health (R01 DK62813 to Y.Y.), the Office of Research and Development, Medical Research Service Department of Veterans Affairs (to D.Y.G.), the Deutsche Forschungsgemeinschaft (project OD 21/1-1) (to S.O.), and a Public Health Service grant (DK56338) that funds the Texas Gulf Coast Digestive Diseases Center. O.O.O. was supported by a UNESCO BAC short-term fellowship and a Macarthur Foundation/University of Ibadan Staff Training Grant.

    1

    Current addresses: O.O.O.: Department of Microbiology, University College Cork, Cork, Republic of Ireland; J.Y.W.: Department of Medicine, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan.

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