Eukaryotic expression and immunization analysis of the DNA vaccine of the major grass pollen allergen of humulus scandens

Objective: To test whether the DNA vaccine of the major grass pollen allergen of humulus scandens (pcDNA3.1-LC2) can be expressed in eukaryatic cells and to further analyze its immunogenicity, immune protection and safety. Methods: HEK293 cells were transfected with the DNA vaccine of the major grass pollen allergen of humulus scandens using Ca₃ (PO4)2. RNA was extracted and used for RT-PCR. Products of PCR were separated on agarose gel electrophoresis. The normal BALB/C mice were immunized with the DNA vaccine. The concentration of IgG, IgE, IL-4 and IFN-γ was measured. BALB/C mice of asthma model were immunized with the DNA vaccine. Lung pathology and BALF cell sediment drop films were advanced; cell count and differential count of eosinophils were conducted, too. The concentration of IL-4 and IFN-γ in the BALF was measured. The concentration of IgG and IgE in the serum was measured at the same time. Results: Our study showed a clear strip at 750 bp and confirmed the expression of the DNA vaccine of the major grass pollen allergen of humulus scandens in eukaryotic cells using agarose gel electrophoresis. The normal mice could produce IgG rather than IgE after being immunized with the DNA vaccine, which suggested the immunogenicity of it. At the same time, IFN-γ concentration increased and IL-4 concentration decreased. Allergic reactions, immune injury and acute lung injury were not caused in the immune process, which suggested that the potential injury risk of the DNA vaccine did not exist. It caused the following changes after the model of asthma of BALB/C mice being immunized with the DNA vaccine: Levels of lung inflammation and infiltration of inflammatory cells and the percentage of eosinophils were significantly reduced. The generation of IL-4 and IgE was inhibited and the generation of IgG and IFN-γ was evoked significantly. The symptoms were relieved greatly if the mice were excited again after being immunized with the DNA vaccine. Conclusion: The DNA vaccine of the major grass pollen allergen of humulus scandens can be successfully expressed in eukaryotic cells. It can induce the TH1/TH2 balance to the transformation of TH1 direction. It has proved to have immunogenicity, immune protection and safety.