Expression of Helicobacter pylori cag12 gene in Lactococcus lactis MG1363 and its oral administration to induce systemic anti-Cag12 immune response in mice

Appl Microbiol Biotechnol. 2006 Sep;72(3):462-70. doi: 10.1007/s00253-005-0285-2. Epub 2006 Apr 4.


To develop an oral vaccine against Helicobacter pylori infection, we have expressed the H. pylori cag12 (HP0532) gene, encoding the outer membrane protein Cag12 (31 kDa), in a live delivery vehicle Lactococcus lactis. The cag12 gene was amplified by polymerase chain reaction (PCR) using the genomic DNA of H. pylori K51 isolated from Korean patients. DNA sequence analysis revealed that the cag12 gene of H. pylori K51 has 98.1 and 97.4% identity with individual cag12 genes of the H. pylori 26695 and J99, respectively. The GST-Cag12 fusion protein, produced using the Escherichia coli expression system, was used to raise a rat polyclonal anti-Cag12 antibody. The PCR-amplified cag12 gene of H. pylori K51 was cloned in the E. coli-L. lactis shuttle vector (pMG36e) and transformed into L. lactis. Western blot analysis demonstrated that the Cag12 protein was expressed in the L. lactis transformant, with a maximum level at the log phase without extracellular secretion. The oral administration of the transformant into mice resulted in the generation of the anti-Cag12 antibody in serum in two out of five cases. These results suggest that the recombinant L. lactis, which expresses Cag12, may be applicable as an oral vaccine to induce protective immunity against H. pylori.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Administration, Oral
  • Amino Acid Sequence
  • Animals
  • Antibodies, Bacterial / biosynthesis*
  • Bacterial Outer Membrane Proteins / genetics*
  • Bacterial Outer Membrane Proteins / immunology*
  • Base Sequence
  • Helicobacter pylori / genetics*
  • Helicobacter pylori / immunology*
  • Lactococcus lactis / genetics*
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Molecular Sequence Data
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / immunology
  • Sequence Alignment
  • Transformation, Bacterial


  • Antibodies, Bacterial
  • Bacterial Outer Membrane Proteins
  • Recombinant Fusion Proteins