Oral immunization of mice with attenuated Salmonella typhimurium expressing Helicobacter pylori urease B subunit / 中华消化杂志

ABSTRACT

Objective To establish attenuated S. typhimurium expressing Helicobacter pylori (H.pylori) urease subunit B (UreB) and determine whether it could be used as oral vaccine against H.pylori Methods H.pylori (SS1 strain) UreB gene fragment amplified by PCR was cloned into the prokaryotic expression vector PTc 01 after sequencing, then transformed into attenuated S.typhimurium SL3261 to acquire SL3261/PTc 01 UreB. The expression of H.pylori UreB in SL3261 was detected by Western blot. Twelve weeks after oral immunization of mice, antibody responses were evaluated using serum and intestinal fluid by ELISA. In vitro stability of PTc 01 UreB plasmid in S. typhimurium SL3261 was confirmed by growing in Luria Bertani medium to 60 generations. Results The UreB gene fragment amplified by PCR was consistent with the sequence of the H.pylori UreB by sequence analysis. Enzyme digestion revealed that the correct PTc 01 UreB was obtained. Western blot showed that 61kD protein was expressed in SL3261/PTc 01 UreB which could be recognized by anti H.pylori UreB antiserum. Anti UreB IgA antibodies in mouse intestinal fluid and IgG antibodies in serum were determined by ELISA. After 60 generations of continuous culture, the recombinant plasmid PTc 01 UreB was stable in SL3261 and had no obvious toxicity. Conclusion The attenuated Salmonella typhimurium expressing H.pylori UreB may be used as oral vaccine against H.pylori infection.