A Candidate Oral Vaccine
to Helicobacter pylori：Fusion Protein of HspA and CtxB
LI Ming-Feng1,2,
HE Zhi-Yong2, LING Zheng1, WANG Jiao-Yang1,
SHENG Xu-Dong1, YANG Guan-Zhen2, WU Xiang-Fu2*
( 1Department of Gastroenterology, 455 Hospital of PLA,
Shanghai 200052, China；2Shanghai Institute of
Biochemistry, the Chinese Academy of Sciences, Shanghai 200031, China )
Abstract Heat-shock
protein A subunit(HspA), an effective immunogen may stimulate the
immunoresponse in human body against challenge of H.pylori. The B
subunit of cholera toxin (CtxB) has been proved to be a potent mucosal
immunogen, actas an adjuvant for vaccine targeted for delivery to the
mucosal-associated lymphoid tissue. A recombinant plasmid expressing bivalent antigen
of HspA and CtxB subunit was constructed as follows. hspA and ctxB
gene was amplified by PCR. The DNA products of hspA and ctxB
were inserted in the prokaryotic expressi on vector pET-22b(＋), respectively, and then the
resulted recombinant plasmid expressinga fusion protein named HCT was
transformed into the E.coli strain BL-21(DE3). hctgene was
measured to be 708 base pairs long, and the fusion protein encoding a
polypeptide of 236 amino acid residues, corresponded to a calculated molecular
masses of 30 kD. Western blot analysis of the recombinant protein HCT confirmed
that it could be specifically recognized by the serum of H.pylori-infected
patients. HspA and HCT labelled 125I were orally administered into
the stomach of mice, respectively, and the radioactivity of 125I in
serum of each mouse was assayed at intervals： 15 min, 30 min, 60 min, 90
min and 120 min. The result indicated that there were high radioactivity counts
in the groups of HCT than that of HspA(P＜0.001). This result suggests
that the CtxB may enhance the volume of HspA absorbed from the intestine of
mice, therefore the recombinant fusion protein HCT may be an effective oral
vaccine for prevention and treatment against the infection of H.pylori.
Key words Helicobacter pylori； HspA； CtxB； fusion protein； oral vaccine
*Corresponding author： Tel, 86-21-64374430-292； Fax, 86-21-64338359； e-mail, [email protected]