Oral Mucoadhesive Newcastle Disease Vaccine: Development, Characterization, and Clinicopathological Evaluation in Challenged Chickens

Effective vaccine delivery is important for sustainable poultry health management, especially in regions facing infrastructural and resource limitations. Natural polymers such as cashew tree gum (CTG) is a promising, low-cost, biodegradable material for oral vaccine delivery, yet its veterinary applications is underexplored. This research assessed CTG’s suitability as a vaccine carrier, its formulation into mucoadhesive microbeads, and its practical value in improving Newcastle Disease (ND) control in poultry production in Nigeria.

CTG was harvested and purified for physicochemical and phytochemical characterization. Broilers and field flocks were then investigated to evaluate CTG-alginate-based mucoadhesive vaccine formulations and immune performance. Hemagglutination inhibition (HI) assays, hematological parameters, heterophil-to-lymphocyte (H:L) ratios, and histopathology of lymphoid organs were assessed. A field survey across six southwestern states also analyzed vaccination practices and risk factors for ND outbreaks.

Purified CTG showed high yield (81.6%), near-neutral pH (4.08), and absence of toxic metals, confirming its safety and biocompatibility. In the field, 63.7% of farms recorded sub-protective antibody titres, largely due to poor biosecurity, vaccination and cold-chain lapses. Experimentally, CTG-alginate microbead vaccines produced significantly higher and more durable antibody titres (GMT ≥203.2; P<0.05), improved lymphoid activity, and lower H:L ratios compared with conventional aqueous vaccines. The local LaSota strain delivered via mucoadhesive beads induced the most persistent protection without affecting growth.

Developing CTG-based vaccine microbeads can significantly enhance vaccine efficacy by prolonging mucosal antigen retention and exposure, resulting in stronger and sustained antibody responses. This approach is cheaper, user-friendly, and practical for poultry farmers in settings with financial, infrastructural, or cold-chain constraints. Collectively, it represents a control package suitable to the production and socio-economic context of backyard poultry farmers in Nigeria and similar regions.