Construction, expression and immunological protection of DNA vaccine of pVAX1-oipA of Helicobacter pylori / 中国免疫学杂志

ABSTRACT

Objective:To investigate the effect of DNA vaccine expressed Helicobacter pylori(Hp) oipA on protecting against Hp infection.Methods:The ORFs of Hp oipA had been inserted into the eukaryotic expressing vector pVAX1 and SGC-7901 cells had been transfected with recombinant plasmid pVAX1-oipA. The expression of oipA had been detected by RT-PCR and ELISA. After extracted and purified, pVAX1-oipA had been injected into BALB/c mice through muscles of right leg one time each week for three weeks(100 ?g each mouse). pVAX1 blank and normal saline had been used as the control groups. Titer of antibodies had been detected by ELISA two months after the last immunization. Based on the confirmation of immunological response in the pVAX1 groups, mice had been given orogastric challenged with live Hp Sydney strain three times(0.5?108/0.5 ml each mouse). Four weeks after challenge, mice had been sacrificed. Histological change and the colonization of Hp in the gastric mucosa had been detected by urease test, the culture of Hp, and electronic microscopy.Results:SGC-7901 cells transfected with pVAX1-oipA had expressed corresponding production at the level of transcription and translation. Immunized mice had been induced anti-oipA antibodies. After challenged with bacterium, as contrast to immunized mice groups injected with pVAX1-oipA, pVAX1 blank, normal saline, the positive rate of urease test of gastric mucosa was 0(0/10), 90%(9/10), 100%(5/5)respectively,the positive rate of cultures of Hp was 20%(2/10), 90%(9/10), 100%(5/5)respectively. Histological findings: the different degree of erosion had been observed in control group, but 80%(8/10)of gastric mucosa were normal in immunized mice.Conclusion:oipA DNA could induce effective immune response in protection against Hp infection.