Antigenic diversity and serotypes of Helicobacter pylori associated with peptic ulcer diseases

OBJECTIVES: Clinical presentation of Helicobacter pylori (H. pylori) infection has marked variation mainly due to the strain diversity and host susceptibility. Although H. pylori is identified as a major risk factor for gastric and duodenal ulcers, the ulcerogenic or pathogenic strain has not been documented yet. The objective of this study was to investigate antigenic types of the ulcerogenic strain of H. pylori. METHODS: The sera of 64 patients were tested by Western blot using Helicoblot 2.0 for six major anti-H. pylori antibodies, together with CLO test and histological examination of gastric biopsy tissues. Thirty-five, nine and 20 patients had duodenal ulcer, gastric ulcer and chronic active gastritis, respectively. The antigenic types of H. pylori were analyzed in 54 patients with positive H. pylori infection. In this study, H. pylori was divided into four serotypes according to the presence and absence of CagA and VagA: type I; CagA (+) and VacA(+), type Ia: CagA (+) and VacA(-), type Ib: CagA(-) and VacA(+), and type II: CagA(-) and VacA(-). RESULTS: There was no difference in the number of bands for six antigens: 3.2 +/- 1.4, 3.0 +/- 1.2 and 3.1 +/- 1.4 in 35 duodenal ulcer, 7 gastric ulcer and 12 chronic gastritis, respectively. The band with 119 kDa was 90.7%, which was the most common band with the order of 35, 30, 26.5, 89 and 19.5 kDa. Type I, la and Ib were positive in 22.2, 42.6 and 27.8%, respectively, which were significantly higher than type II (p < 0.05). There was no difference in the positive rates of four urease subtypes between the four serotypes.

Studies on lepromin and soluble antigens of M.leprae: their classification standardization and use.

Before the discovery of armadillo as a susceptible animal the source of M.leprae was limited and hence the use of lepromin was not common in the field. In recent times, the soluble antigens of armadillo-derived M.leprae have been used extensively in the field. Although the results of the study show that these antigens do not differentiate always a susceptible form from the resistant form, they are able to segregate the polar forms of leprosy. In a given field situation the criteria for diagnosis is so stressed that leprosy is overdiagnosed and within one year of follow up nearly half the number of cases are noted as not leprosy. Hence, in such situations lepromin reaction would be definitely a poor correlate with the type of leprosy. However, in hospital based studies the lepromin reaction has always been and would remain useful in confirming the classification (Sengupta et al 1984). Lepromins and M.leprae soluble antigens have gone through extensive standardization procedures. As these antigens contain mostly common mycobacterial antigens along with the M.leprae-specific antigens, these antigens are unable to specifically diagnose M.leprae infection. After purification of M.leprae from infected armadillo tissue, it was expected that the soluble antigen of M.leprae would probably be as useful as tuberculin. However, this was not found to be true in case of lepromin. Specificity for M.leprae has been noted in the epitopes (antigenic sites) on cross reacting molecules (12 kd, 18 kd, 28 kd, 35 kd, 36 kd) of mycobacteria (Ivanyi et al 1983; Watson 1989). These specific epitopes, if synthesized, could be of use as skin test antigens for determining M.leprae infection.(ABSTRACT TRUNCATED AT 250 WORDS)