A Systematic Review of Novel Strategies in the Design of Oral Veterinary Vaccines Against Agalactia: The Role of Nanocarriers and Targeted Antigen Selection

Agalactia is a complex infectious syndrome that predominantly affects lactating small ruminants, with clinical manifestations such as mastitis, arthritis, keratoconjunctivitis, and milk suppression. Current control relies heavily on antimicrobial therapy and injectable vaccines, which face limitations related to administration logistics, restricted mucosal immunity, and growing concerns over antimicrobial resistance (AMR). In this context, oral vaccination has emerged as a strategic alternative, capable of eliciting both mucosal and systemic immune responses via gut-associated lymphoid tissue (GALT). This systematic review aims to assess recent innovations in designing oral veterinary vaccines against Agalactia, focusing on nanocarrier technologies, antigen stabilization strategies, mucosal adjuvants, and species-specific immunological dynamics. A comprehensive literature search covering studies published between ۲۰۰۰ and ۲۰۲۴ identified ۴۷ eligible sources. Findings reveal that polymeric and lipid-based nanocarriers enhance antigen protection and targeted mucosal delivery, while encapsulation methods such as biofilm integration and lyophilization improve antigen stability and field readiness. Polysaccharide-based adjuvants and microbiota-modulating agents (m-biotics) demonstrate potential in boosting mucosal immunogenicity, though interspecies variability in GALT remains a challenge. Despite technological progress, gaps persist in regulatory harmonization, manufacturing scalability, and long-term field validation. Notably, few studies directly measured the impact of oral vaccines on antibiotic use reduction. This review concludes that the next generation of oral Agalactia vaccines must integrate antigen targeting, mucosal immune modulation, and regulatory foresight to achieve clinical efficacy and alignment with One Health objectives in sustainable livestock management.

کلیدواژه ها:

oral veterinary vaccines ، Agalactia ، nanocarriers ، antigen stabilization ، mucosal immunity ، GALT