A study on the development and applications of polyclonal antibody for the detection of Helicobacter pylori in serum and saliva

Abstract

In Vietnam, it’s annually estimated that there are 15,000-20,000 cases of gastric cancer, in which Helicobacter pylori (H. pylori) is the most interested agents and has been classified as a group I of carcinogens by the International Agency for Research on Cancer (IARC) based on two main toxins CagA and VacA. CagA (cytotoxin-associated gene A) encoded by the cagA gene is a protein that makes highly immune response and presents in 50-70% of H. pylori strains with a very high rate of gastric cancer. Rapid detection of H. pylori carrying cagA will contribute to warning and orienting for treatment. The aim of the study, therefore, is to produce and apply polyclonal antibodies for rapid detection of H. pylori cagA. Protein CagA was used as antigen inducing the immune response in white female mice (Swiss) at 6-8 weeks old. Indirect Elisa and Ouchterlony double immunodiffusion were performed to check antibody responses. The limit of detection and antibody titers were calculated by two fold dilution of antigen and antibody. Indirect Elisa was also used for detection of H. pylori carrying cagA in saliva and serum samples. The suitable immunogen dose was 20 mg protein/mouse. The titer of antibody was 51,200, and antibody affinity was high. Using antibody to detect H. pylori carrying cagA gene in saliva and serum samples got satisfying results.