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Background: Brucella is a gram-negative intracellular bacterium. Since Brucella brings about health and socio-economic problems, its control is of primary importance. The common method of vaccination includes using live attenuated strains of this bacterium. This study was done to evaluate the immunogenicity of Brucella aburtus P39 gene in Balb/c mice. Materials and Methods: In this experimental study, P39 gene was amplified by polymerase chain reaction (PCR) method and after extraction, it was sub-cloned to eukaryotic expression vector pcDNA3. The intramuscular injection of the obtained plasmid to the Balb/c mice was done in three stages. After the last vaccination, immunologic tests, such as proliferative response in lymphocytes, IFN- assessment, IL-5, and determination of IgG2a and IgG1, were run. Results: The level of activation in splenic lymphocytes response was 3.6 and the measured IFN- was 3 ng/ml, whereas IL-5 was insignificant. IgG2a and IgG1 titers were 1.640 and 1.40, respectively. Conclusion: The findings of the immunological analysis show the appropriate immune response in Balb/c mice model after the injection of P39 gene containing plasmid. The immune system response was in Th1 form which decreased the number of bacteria in spleen. Therefore, P39 gene is of appropriate immunogenicity and DNA vaccination is efficient in the activation of cell immune response against this bacterium.

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Background: Hypervariability of hepatitis C virus (HCV) proteins is an important obstacle to design an efficient vaccine for the infection. To construct a protective vaccine against HCV, a DNA vaccine containing conserved epitopes of the virus was designed. To enhance the induced immune responses, adjuvant activity of N-terminal domain of gp96 (NT(gp96)) was used.

Materials and Methods: A multi-epitope (PT) DNA vaccine encoding four HCV immunodominant cytotoxic T lymphocyte epitopes (HLA-A2 and H2-D^d) from Core, E2, NS3 and NS5B antigens in addition to a T-helper CD4+ epitope from NS3 protein and a B-cell epitope from E2 protein was designed and constructed. Then, NT(gp96) was fused to the PT DNA (PT-NT(gp96)). The stimulated cellular and humoral immune responses of PT and PT-NT(gp96) were evaluated in mice model.

Results: According to multicolor flow cytometry assay, the frequency of CD8+ T-cells producing IFNγ and TNFα in the splenocytes of immunized mice with PT-NT(gp96) (6.8%, 4%) was significantly higher than those of immunized with PT (0.9% , 0.8%), respectively. The same results have obtained in hepatic lymphocytes of the vaccinated mice. The level of IgG, IgG1 and IgG2a in the mice vaccinated with PT-NT (gp96) was significantly higher than the value obtained from the mice immunized with PT.

Conclusion: The results showed that PT DNA vaccine induces immune responses in mice model. Fusion of NT (gp96) to PT DNA vaccine causes to enhance cellular and humoral immune responses against HCV compared to sole PT vaccine.