Plant biofactories have proven to be a valuable platform for producing numerous antigens effective in the prevention and diagnosis of various infectious diseases, including in the veterinary field. In this context, vaccines represent a powerful prophylactic tool capable of limiting the global impact of zoonoses as well as contributing to the reduction of antimicrobial use, thereby counteracting the emergence of antibiotic resistance. In addition to producing antigens in their native form, particularly for the development of diagnostic assays, antigens with enhanced immunogenic properties have been synthesized for vaccine formulation. Activities focus on viruses such as those responsible for influenza, Infectious Bursal Disease, Newcastle Disease, and Porcine Reproductive and Respiratory Syndrome, as well as on bacteria (both zoonotic and non-zoonotic) including Brucella suis, Chlamydia abortus, and Coxiella burnetii.