Assessing the efficacy of modified plant vaccine antigens in animal immunization: A systematic review

Background: Edible vaccines produced in genetically modified plants represent a novel approach to immunization, to express antigens capable of eliciting immune responses at mucosal surfaces. This method provides a potential cost-effective solution for vaccine delivery, particularly beneficial in resource-limited settings. Aim: This review aims to assess the efficacy of edible vaccines derived from transgenic plants in eliciting immune responses in animal models against various infectious and parasitic diseases. Methods: A comprehensive search of PubMed, Embase, and Scopus up to June 2024 identified 138 references. Following Cochrane guidelines, PRISMA standards, and the CAMARADES risk of bias checklist, 16 studies met the inclusion criteria and focused on edible vaccines for animal immunization. Results: The findings indicate that edible vaccines can effectively elicit both humoral and mucosal immune responses in animals. For instance, transgenic plants expressing antigens for hepatitis B and human papillomavirus demonstrated high efficacy, with significant increases in antigen-specific antibody levels post-immunization. Studies on bacterial diseases using LT-B antigens from Escherichia coli expressed in corn showed robust, sustained antibody responses. Additionally, for parasitic diseases, transgenic rice expressing Ascaris antigen reduced larval burden, indicating protective efficacy. However, variations in immune response depending on plant type and antigen stability highlight the need for further optimization to achieve consistent efficacy across different diseases. Conclusion: Edible vaccines from antigen-expressing plants show promise as a viable alternative to traditional methods, with strong immunogenicity in animal models. Further research is needed to address variability and optimize production for human use, potentially improving vaccine access in underserved regions.