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In search of immunogenic Helicobacter pylori proteins by screening of expression library
I Lazowska1, L Trzeciak, R Godlewska
1Department of Gastroenterology, Medical Center for Postgraduate Education, Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology, Warsaw, Poland.
Background:
Prevention of Helicobacter pylori infection may help to control related gastritis, peptic ulcer and cancer. Of the possible preventive measures, immunization was successfully employed in various animal studies. However, no immunization protocol has been accepted for humans. A better characterization of the immune response against the pathogen may be required before a human vaccine is developed.
Aim:
To identify bacterial proteins which induce an immune response in infected humans or H. pylori-immunized rabbits.
Methods:
An expression library of H. pylori genes was screened with sera from infected humans and from immunized rabbits. Positive clones were partially sequenced and identified on the basis of a homology search of a H. pylori genome database. Encoded proteins were expressed directly from positive clones and analyzed by SDS-PAGE/Western blot techniques.
Results:
114 positive clones were isolated: 79 by screening with human sera and 35 by screening with rabbit sera. Western blot analysis demonstrated that selected clones encoded one or more strongly immunoreactive proteins. 64 clones selected with human sera had no counterparts among clones from screening with rabbit serum. 13 of these clones encoded a total of 21 unknown H. pylori proteins. 17 clones selected with rabbit sera were not immunostained with human sera. They represent 2 various regions of the H. pylori genome which encoded 3 bacterial proteins of unknown function.
Conclusions:
Screening of H. pylori expression library identified immunogenic proteins - potential vaccine antigens.