Preparation of oral Helicobacter pylori HpaA nucleic acid vaccine with interlukin-2 as adjuvant to prevent Helicobacter pylori infection / 中华消化杂志

ABSTRACT

Objective To construct a nucleic acid vaccine expressing H.pylori HpaA and inter- leukin-2 gene and to identify the immunogenicity of the vaccine proteins in vitro and protection in vivo. Methods The H paA gene fragment was amplified by polymerase chain reaction(PCR) from the genomic DNA of the standard H.pylori strain 17874.Mouse interlukin(IL)-2 gene was amplified from pClneo- IL-2.The HpaA and IL-2 were cloned into pUCmT vector.After DNA sequences of the amplified HpaA gene and IL-2 were confirmed,both were cloned into the eukaryotic expression vector pIRES through a serial of enzyme digestion and ligation reactions.The recombinant plasmids were screened by PCR and restriction enzyme digestion.Then,recombinant pIRES-HpsA-IL-2 was transfected to COS-7 cells using Lipofectamine~(TM)2000.The immunogenicity of HpaA and IL-2 protein was detected by SDS- PAGE and Western blot.The recombinant plasmids were transformed to LB5000 and then to final host SL7207.The recombinant strains were passaged repeatedly.The mice were challenged with H.pylori after 4 weeks of inoculation of nucleic acid vaccine.H.pylori infection was detected by rapid urease test.Results The amplified HpaA gene fragment and IL-2 were confirmed by sequence analysis.The eukaryotic expression vector plRES and the pIRES-HpaA-IL-2 construction were confirmed by PCR and restriction digestion.The expressions of HpaA(30 000) and IL-2(14 000)protein by pIRES-HpaA-IL- 2 were detected by Western blot.The in vivo study showed that 75.0% and 58.4% of mice vaccinated by HpaA-IL-2 and HpaA,respectively,were protected anaigst H.pylory infection,which was signifi- cant different in comparison with PBS control (P