Study on the immunogenicity of pcDNA۳.۱(+)-cagT recombinant vector against Helicobacter pylori in BALB/cmice

Background and aims: The role of Helicobacter pylori in the development of gastric ulcer and gastrointestinal cancer was identified in thisstudy. More precisely, the study focused on the creation of a DNA vaccine based on the cagT gene of this bacterium and the investigationof its immunogenicity against H. pylori in infused BALB/c mice.Materials and Methods: To this end, the pcDNA۳.۱(+)-cagT was prepared and transformed into Escherichia coli. Then, animals were injectedwith recombinant pcDNA۳.۱(+)-cagT plasmid, pcDNA۳.۱(+)-cagT + nanoparticles, and pcDNA۳.۱(+). After the plasmid purification andconfirmation of the transformation by digestion and polymerase chain reaction (PCR), chitosan nanoparticles were synthesized using theionic gelation method. Next, the animals were classified into three groups each including ۲۱ mice. The injectable solutions includingpcDNA۳.۱(+)-cagT, pcDNA۳.۱(+)-cagT + nanoparticles, or empty pCDNA۳.۱ (as a control group) were injected into the quadricepsmuscle of mice, separately. Finally, the blood and tissue samples of each mouse were collected ۱۵, ۳۰, and ۴۵ days after the last injection,and the expression levels of transforming growth factor-beta (TGF-β۱), interleukin-۴ (IL-۴), and interferon-gamma (IFNγ) were evaluatedby real-time PCR.Results: The IFNγ and TGF-β۱ expression increased in the infused mice (P < ۰.۰۱) while the IL۴ expression represented a significantdecrease (P < ۰.۰۱). Moreover, the IFNγ and IL۴ expression level in pcDNA۳.۱(+)-cagT + nanoparticle significantly altered (P < ۰.۰۱)compared to the pcDNA۳.۱(+)-cagT group although the TGF-β۱ expression was not significantly different (P = ۰.۰۷۵). Contrarily, the cagTgene expression in the tissue samples of both groups was significantly different ۱۵, ۳۰, and ۴۵ days after the last injection (P < ۰.۰۱).Eventually, the expression of the cagT gene in the infused mice by pcDNA۳.۱(+)-cagT and in the nanoparticle group was not significantlydifferent ۴۵ days after the last injection (P = ۰.۱۰۵).Conclusion: In general, the decrease of IL-۴ expression was observed in the injected mice by pcDNA۳.۱(+)-cagT and indicated that theimmune system work by a Th۱ pattern. The findings showed that a pcDNA۳.۱(+)-cagT construct combined with chitosan nanoparticlescan increase the stimulation of the immune system in an animal model and thus it can be used as an appropriate method for controllingH. pylori infection.

Keywords:

H. pylori , pcDNA۳.۱(+)-cagT , Cytokine genes , Chitosan nanoparticles