Polymeric Nanocarriers as Potent Delivery Platforms for DNA Vaccines Against the Virulent <em>Orthoavulavirus javaense</em> in Chickens

Vaccination represents the cornerstone of Newcastle disease control. Nanotechnology offers a promising approach to improve the effectiveness of DNA vaccines, supporting their use as an alternative to conventional platforms. Herein, the virulent Orthoavulavirus javaense (OAV-j) fusion (F) gene was cloned into a DNA expression plasmid (pDNA). After validating the constructed pDNA-F and confirming robust intracellular protein expression in vitro, three polymeric nanoparticles (NPs)–based formulations were generated using Chitosan (Cs), poly(lactic-co-glycolic) (PLGA), and poly(amidoamine) (PAMAM)-Dendrimers. Physicochemical and morphological analyses confirmed excellent formulation characteristics, including optimal nanoscale size, formulation-specific surface charge, and effective DNA–carrier interactions. Encapsulation/loading and release profiles further confirmed their successful preparation. In vivo experiments were conducted to assess the immunogenicity and protective efficacy of these formulations compared to naked pDNA-F using various administration routes. Following intramuscular administration, PAMAM-Dendrimers-pDNA-F demonstrated superior efficacy, with 100% survival, the highest post-challenge antibody titers, and a pronounced reduction in viral shedding. Moreover, intranasal administration of PLGA-NPs-pDNA-F demonstrated enhanced efficacy, with 90% survival. Interestingly, naked pDNA-F surpassed the Cs-NPs-pDNA-F in both immune response and clinical protection, with Cs-NPs-pDNA-F exhibiting the lowest overall performance. These findings underscore the importance of route-dependent formulation performance and demonstrate that a well-designed carrier significantly improves DNA vaccines effectiveness.