OBJECTIVETo determine the immunoprotective effects of rUreB and rHpaA bivalence genetic engineering vaccine with inner adjuvant of rLTB on BALB/c mice against H.pylori strain SS1 infection.

METHODSrUreB, rHpaA, rLTB-rUreB-rHpaA, rLTKA63, rLTB and rLTB were collected by NTA-Ni affinity chromatography. Western blot was applied to demonstrate the immunoreactivity of the recombinant protein antigens. Adjuvant activities of rLTB, rCTB and rLTB-rUreB-rHpaA were determined by GM1-ELISA. H.pylori strain SS1-infected BALB/c mouse modal was established to measure immunoprotective effects of different compositions of antigens and adjuvants. H.pylori in gastric biopsy specimens was examined by routine isolation method and silver staining method. Two ELISAs were established to detect specific S-IgA in gastric juices and specific IgA in sera of the immunized mice.

RESULTSrUreB, rHpaA and rLTB-rUreB-rHpaA were recognized by commercial antibody against whole cell of H.pylori and were able to combine to the bovine GM1. The protective rate in the mice immunized with single rUreB or rHpaA was lower than 70%. When using rUreB or rHpaA plus rLTB or rCTB, the positive rates increased to 75.0%-83.3%. With different combination of antigens and adjuvants, the immunoprotective rate of rLTB-jrUreB-rHpaA was as high as 100%, and then was 91.7% for rUreB+rHpaA+rCTB+rLTKA63 and was 90.9% for rUreB+rHpaA+rLTB. Both the rLTB and rCTB showed remarkable effects to induce specific IgA in sera and specific S-IgA in gastric juices of the immunized mice, and the former showed stronger S-IgA-inducing ability than the latter. The positive rates of specific IgA were basically identical to the corresponding mouse immunoprotective rates. S-IgA positive rates specific to rUreB and rHpaA in rLTB-rUreB-rHpaA immunized mice were 100% and 91.7%, respectively.

CONCLUSIONThe rUreB and rHpaA possess qualified immunoreactivity and antigenicity. The rLTB and rCTB can show adjuvant activity of mucosal immunization. The high immunoprotective rate of Helicobacter pylori UreB and HpaA bivalence recombinant vaccine with inner adjuvant in mice is associated with high dosage of rLTB, larger molecular weight of the antigen and the high levels of local specific S-IgA.