Abstract
Newcastle disease (ND) is a common viral disease of poultry birds that causes huge economic losses in the poultry industry. Sudden outbreaks of ND can cause up to 100% mortality in the flock before showing major clinical signs of the disease. There is no effective treatment for this disease till to date, so its control depends upon vaccination. Currently available vaccines have some issues with delivery and efficacy, so research is being done to find suitable adjuvants for vaccination. Among several adjuvants being tried, nanoparticles (NPs), especially organic NPs, are gaining importance. Chitosan is an organic natural compound, and its NPs are favorable natural biopolymers because of non-toxic, biodegradable, and bioactive properties. Mucosal chitosan-based vaccines are being proven to effectively control the disease as these are potential mucosal adjuvants and cause sustained release of the antigens that can enhance immunity levels. Researchers incorporated free amino and carboxyl groups to address the solubility issues of chitosan and enhance its solubility. These modifications tremendously increase the application of chitosan NPs as vaccine delivery agents. Research indicates that chitosan-derived nanoparticles when loaded with Newcastle disease virus (NDV), whole or a subunit, produce approximately complete immunity by producing cell-mediated and humoral immunity. This review highlights that chitosan-based NPs are potential adjuvants that resolve the problems related to currently available vaccines.