Plasmid DNA (pDNA)-based vaccines have emerged as effective subunit vaccines against viral and bacterial pathogens. In this study, a DNA vaccine, namely plasmid internal ribosome entry site-HN/F, was applied in ovo against Newcastle disease (ND). Vaccination was carried out using the DNA vaccine alone or as a mixture of the pDNA and dextran-spermine (D-SPM), a nanoparticle used for pDNA delivery. The results showed that in ovo vaccination with 40 µg pDNA/egg alone induced high levels of antibody titer (P0.05). Higher antibody titer was observed in the group immunized with 40 µg pDNA/egg at 4 weeks postvaccination. The findings also showed that vaccination with 40 µg pDNA/egg alone was able to confer protection against Newcastle disease virus strain NDIBS002 in two out of seven SPF chickens. Although the chickens produced antibody titers 3 weeks after in ovo vaccination, it was not sufficient to provide complete protection to the chickens from lethal viral challenge. In addition, vaccination with pDNA/D-SPM complex did not induce high antibody titer when compared with naked pDNA. Therefore, it was concluded that DNA vaccination with plasmid internal ribosome entry site-HN/F can be suitable for in ovo application against ND, whereas D-SPM is not recommended for in ovo gene delivery.

Vaccine Research تحقیقات واکسن

The current method to detect antibody titre against infectious bursal disease virus (IBDV) in chickens is based on enzyme-linked immunosorbent assay (ELISA) using whole virus as coating antigen. Coating the ELISA plates requires a purified or at least semi-purified preparation of virus as antigen, which needs special skills and techniques. In this study, instead of using whole virus, recombinant protein of hexahistidine tag (His 6 tag) and VPX protein of IBDV expressed in E. coli was used as an alternative antigen to coat the ELISA plates. There was a good correlation coefficient (R ² = 0.972) between the results of the ELISA using plates coated with monoclonal antibody against His 6 tag and those of the commercial IBDV ELISA kit. Hence, His 6 tag and VPX recombinant protein expressed in E. coli has the potential for the development of ELISA for the measurement of IBDV-specific antibody.

Brucellosis is a chronic and debilitating disease that affects various organs and has many negative consequences in the field of health and economy in Iran. Brucella outer membrane proteins, especially OMP31, OMP28, are important in vaccine design, production of required antigens, serum diagnostics, production of safe recombinant proteins with appropriate immunogenicity, and cost-effective production. Selecting the appropriate expression and hosting system for the expression of these recombinant proteins that can be produced safely, massively and economically is one of the main priorities in the production of vaccines and antigens used. In this study, plasmid pnz8149 was extracted from Lactococcus lactis. Brucella OMP31 gene was then amplified into specific vectors after amplification with specific primers and digestion of nco1 and bmh1 enzymes. Using electroporation, the plasmid containing the gene was transferred to Lactococcus lactis. In order to select transformant lactococci, lactococci containing recombinant plasmid pNZ8149 + OMP31 were transferred to Elliker medium. Finally, the presence of recombinant plasmid pNZ8149 + OMP31 in Lactococcus lactis was investigated by PCR, enzymatic digestion and sequencing. The quantity and purity of pnz8149 extracted plasmid were 123.8 ng and 1.93 μg, respectively. Due to the design of specific primers for amplification of OMP31 gene of this fragment, the target of Brucella bacterium genome was successfully amplified to 723 bp. OMP31 gene insertion in pnz8149 vector was successfully performed and the presence of recombinant plasmid pNZ8149 + OMP31 in Lactococcus lactis was confirmed. Given that the product of the OMP31 gene is a valuable candidate for the production of vaccine, this gene can be of significant target in research associated with vaccine production for treatment of brucellosis.