Helicobacter pylori serology in two MOH areas of the Western Province of Sri Lanka

Abstract

Thus far five studies on H. pylori show a prevalence range from 3 - 70% in Sri Lanka. However there are no published studies based on serology and virulence factors.Cytotoxin associated protein A(CagA), urease and vacuolating cytotoxin A (VacA) have been described as virulence factors to H. pylori. This study was done to determine the sero-prevalence of IgG to Helicobacter and CagA in a representative population attributable to age groups and to determine the host response to virulent antigens such as CagA, urease, VacA and other major antigen found on H pylori. Three hundred and fifty nine healthy volunteers between the ages of 1 to 94 years, with equal distribution of males to females participated in this study. The sero prevalence of IgG to H. pylori and CagA was determined using enzyme linked immunosorbent assay. The presence of IgG antibodies to several major antigens of H. pylori were determined in 48 samples (positive by IgG to H. pylori and/or positive by IgG to CagA) using an in-house western blot assay. Data was analysed by a chi square test. The study consisted of 359 serum samples from 180 males and 179 females. Only 37 (10.3%) of the. 359 serum samples were positive for IgG to H. pylori. Anti CagA was detected in 29/359 (8.1% ) . In the 48 samples studied by immunoblotting for major antigens (CagA-120Kda, VacA-89Kda, Urease-66Kda, 35Kda, 26 Kda, 19 Kda) the commonest western blot band was VacA(89Kda). In conclusion, the prevalence of 10.3% seems to below, but the presence of CagA antibody in H. pylori negative sera, indicates that responses in the host may not be always detected by routine assays. This may be due to a different strain used in assay, genetic differences in the host not enabling the host to mount a response, or to cross reactivity.