Serological response to Helicobacter pylori recombinant antigens in Chilean infected patients with duodenal ulcer, non-ulcer dyspepsia and gastric cancer

We have previously cloned 10 Helicobacter pylori antigen genes from a Chile an strain including: cytotoxin VacA, a truncated region of CagA (called A17 ), a species-specific protein (Ag26), urease subunits (UreA, UreB), a flage llin, (FlaB), heat shock proteins (HspA and HspB), an adhesin (HpaA) and a lipoprotein (Lpp20). Immunogenicity of these antigens was tested by immunob lot with sera of Chilean infected patients, revealing that HpaA, A17, HspB and VacA were more frequently recognized (86%, 820/o, 68% and 68%, respecti vely). According to the clinical condition, it was determined that Lpp20 wa s preferentially recognized by sera from non-ulcer dyspepsia patients (80%) , A17 and VacA by patients with duodenal ulcer (92% and 83% respectively), and HspB by patients with duodenal ulcer (83%) and gastric cancer (90%). An ELISA was developed with a purified mixture of A17 and VacA antigens to te st the different groups of patients. It was found that sera from duodenal u lcer patients showed higher values than those from non-ulcer dyspepsia pati ents, but this difference was not significant (p<0.2). Moreover, sera from gastric cancer patients showed values lower than those from non-ulcer dyspe psia patients (p<0.019). These results indicate that, in the Chilean popula tion, antibodies raised against VacA and A17 are not markers either for duo denal ulcer or for gastric cancer.