Newcastle disease (ND) is a highly contagious and severe disease that affects birds, including domestic poultry, causing significant economic losses to the poultry industry. The disease is caused by the ND virus (NDV). Despite extensive vaccination efforts against NDV, controlling the disease remains challenging, primarily due to the emergence of new genotypes. Recent attention has focused on calcium phosphate nanoparticles (CaP NPs) as promising adjuvants for vaccines. This study aimed to design and construct CaP NPs containing inactivated NDV genotype VII and evaluate their safety and humoral immunogenicity in chickens. Following virus propagation in specific-pathogen-free eggs and inactivation with formalin, CaP NPs containing inactivated NDV were prepared using in situ and adsorption methods. The NPs were characterized for shape, size, polydispersity index and surface charge. Chickens were immunized subcutaneously with CaP NPs containing inactivated NDV and the humoral immune response against NDV was assessed using HI and enzyme-linked immunosorbent assays. Results showed a significant increase in the mean antibody titer against NDV in chickens treated with both NP structures compared to control groups. No significant difference was observed between the two NP preparation methods. The safety of CaP NPs containing inactivated NDV was confirmed. However, mucosal immunization with these NPs did not yield satisfactory results indicating the need for further research. Overall, this study confirmed the positive role of CaP as an adjuvant in enhancing the humoral immune response against NDV via injection and highlighted the need for continued research on mucosal immunization with the NPs.
Darabi-Aref et al. (Wed,) studied this question.