ETECTION OF ADHERENCE FACTORBABA2 GENE IN HELICOBACTERPYLORIINFECTED PATIENTS USING CONVENTIONAL PCR TECHNIQUE

Abstract

Helicobacter pylori is a Gram-negative spiral bacterium that inhabits the gastric mucosa of the human stomach in approximately half of the world's population for a life time. H.pylori infection is widespread in humans; it is present in 20% to 50% of the population in the developed countries and 80% of the population in developing countries. Infection of this unique ecological niche by H.pylori display only asymptomatic gastritis whereas a small proportion may progress into peptic ulcers, persistent infection also increases an individual's risk for development of gastric adenocarcinoma,and gastric mucosa-associated lymphoid tissue lymphoma. In 1994, H.pylori was declared a group I carcmogen.

Different degrees of bacterial virulence, environmental influences, and host factors are believed to contribute to the differential clinical squeal of the infection. For the bacterium to succeed in its long-term colonization in the human stomach a set of bacterial virulence determinants was developed for initial adhesion; adherence of H.pylori to gastric mucosa is widely assumed to play an important role in the initial colonization and long term persistence; and for the altering gastric physiology. The major virulence factors of H.pylori is vaculating cytotoxin (Vac A), which causes cytoplasmic vacuolization in gastric epithelial cells, another well-characterized virulence factor is cytotoxin associated gene (cag A), which encoded by one of the genes located in the cag pathogenecity island (PAl), and the blood group antigen binding adhesin (BabA), encoded by BabA2 gene has been shown to mediate adherence of H. pylori to human gastric Lewis b blood group antigens on gastric epithelial cells that function as receptors for H.pylori adhesin and mediate its attachment to gastric pit and surface mucosa.

Currently, there are several popular methods for detecting the presence of H.pylori infection, each having its own advantages, disadvantages, and limitations. Several invasive and noninvasive tests are available according to whether or not endoscopic biopsy is necessary. Non invasive tests, based on peripheral samples, such as blood, breath samples, stool, urine, or saliva for detection of antibodies, urease activity (UBT), or bacterial antigens respectively. Invasive tests such histological evaluation, culture, polymerase chain reaction (PCR), and rapid urease tests are typically performed on tissue obtained at endoscopy

The aim of this study is detection of BabA2 gene to estimate its prevalence in our H.pylori infected patients as a one of the major virulence factors associated with H.pylori and contribute to the different clinical outcomes, and to evaluate the efficiency of using conventional PCR technique as a powerful technique for its molecular detection in gastric tissue biopsies obtained during endoscopy from patients infected by H.pylori, evaluation of the clinical outcomes due to infection by BabA2 positive strains, detection of the Lewis b expression status, and its relation to H.pylori colonization density and subsequent disease outcome.