Adjuvants were described as substances used in combination with a specific antigen that produced a more robust immune response than the antigen alone. There is an urgent need for the development of new and improved vaccine adjuvants. Infectious Bronchitis (IB) is one of the most relevant infectious diseases of poultry, and it is caused by the Infectious Bronchitis Virus (IBV). Most commercially available IB vaccines are inactivated whole-virus preparations that do not induce long-term protection. This can be overcome by the administration of an effective immune adjuvant that generates a strong enough immune response to provide long-term protection against infection. Within the scope of the project, new adjuvant candidates were developed containing glycoside molecules in oil-based (W/O) and examined for the first time against IBV in poultry and commercialized. For this purpose, the IBV H120 strain was produced in Specific Pathogen-Free (SPF) Embryonic Chicken Eggs (ECE) and 50% Embryo Infectious Dose (EID50) values were determined. Subsequently, formalin-inactivated virus and new candidate vaccine adjuvants were used in the vaccine formulation. After quality control and stability tests, vaccine formulas were administered to chickens subcutaneously. Vaccination efficiency was evaluated for serum antibody (IgY), mucosal antibody (IgA) responses, and changes in cytokine levels by ELISA. The cellular response was measured as a ratio analysis of the T lymphocyte subset (CD4+/ CD8+) in peripheral blood by flow cytometry. Evaluation of the protective efficacy of vaccine formulations was determined using the virus challenge test in Specific Pathogen-Free (SPF) challenge ocular-nasal route with M41 virus strain and their protection was assessed in trachea and kidney post-challenge to determine the virus shedding using RT-qPCR. The physical and chemical analysis values of the newly developed adjuvants (CORALVAC) within the scope of the project are among the limit values. When the stability, which is one of the critical parameters in the use of adjuvants, is evaluated, the product maintains its stability for a long time at 4?C. The low emulsion viscosities of CORALVAC adjuvants facilitate their injectability. When the responses of anti-IBV antibodies were examined, faster and higher antibody responses were obtained compared to commercial adjuvants. When the protection of the vaccine was examined after the challenge test, higher IgA antibody responses were obtained compared to commercial adjuvants. The cytokine levels of IL-1β, IL-2, IL-4, and IFN-γ at Days 14 and 28 after vaccination were examined. On day 28, splenocyte T lymphocyte subsets (CD4+ and CD8+) were examined by flow cytometry analysis. Considering the findings obtained, it was determined that the CD4+ and CD8+ responses of CORALVAC adjuvants were balanced. Tissue samples taken from the trachea, cecal tonsil, lung, and kidney were examined by RT-qPCR to evaluate the protective efficacy of vaccine formulations and to determine the protection of the vaccine and virus spread after challenge, and positive results were obtained compared to commercial adjuvants. When the results obtained within the scope of the study were examined, the CORALVAC adjuvants developed within the scope of the project were found suitable for use in commercial vaccines.
Audience take away:
- Within the scope of the project, the training of new young academics was supported.
- The efficacy of alternative adjuvant systems for commercially developed vaccines is presented.
- The efficacy of oil-based adjuvants in poultry vaccines was investigated.
- For the prevention of infectious bronchitis in poultry industry, which causes great economic losses, a local adjuvant system has been developed.