Nanoparticle-based mucosal vaccines for animal infectious diseases: Delivery strategies, immune mechanisms, and veterinary applications in ruminants, swine, and poultry

Many animal pathogens enter through the respiratory, gastrointestinal, or reproductive mucosa, where early replication and shedding can occur before systemic immunity controls disease. Injectable vaccines remain effective at limiting severe disease and mortality, but often induce weaker local responses, including secretory immunoglobulin A (SIgA), local immunoglobulin G (IgG), mucosal memory B cells, and tissue-resident memory T (T RM ) cells. Nanoparticle formulations may improve antigen stability, mucosal residence, cellular uptake, and antigen–adjuvant co-delivery, but these benefits depend on the carrier, cargo, route, and target species. This review links delivery barriers, nanoparticle platforms, and immune mechanisms to target-animal evidence from ruminants, swine, and poultry. Protection is assessed alongside immunogenicity through challenge outcomes, pathogen load, shedding, colonization, lesions, and transmission-related outcomes, with attention to maternal and lactogenic immunity, mass administration, dose uniformity, field delivery, food-animal safety, manufacturing feasibility, regulatory expectations, and cost. The value of a mucosal nanovaccine is therefore judged by its antigen–carrier combination, administration route, target species, and protective evidence rather than nanoparticle use alone.