Toll-Like Receptor Agonist-Based Nanomedicines as Veterinary Immunotherapies

Abstract

Many infections affecting animals enter across mucosa, needing of secretory immunity to reject the disease; protection against some pathogens must be early, fast, and specifically elicited, while from others must be wide enough to fight against variable serotypes. Today, however, most veterinary vaccines are injectable (not recommended for chicken and small fishes), aimed to control clinical signs instead of eradicating the disease and poor inducers of secretory immunity. These drawbacks are compensated by vaccination with live attenuated agents, by using potentially toxic oily adjuvants and with indiscriminate use of antibiotics. In this review, the benefits of commercial and experimental nanomedicines acting as immunostimulants and vaccine adjuvants made of toll-like receptor (TLR) agonists loaded in nanoparticles (NP-TLR agonists), are presented. Np-TLR agonists induce a magnified, sitelimited triggering of innate immunity; also allow modifying the administration route from injectable to mucosal or nebulized, provide structural protection to TLR agonists and avoid their diffusion far from the administration site. Future implementation of immunotherapies based on Np-TLR agonists will be discussed as a function of scale production feasibility.