Lactococcus lactis as a New Strategy for Oral Vaccination: Current Insights and Future Perspectives

Lactococcus lactis, a safe food-grade lactic acid bacterium, has attracted increasing attention as a live biotherapeutic platform for mucosal vaccine development. Its genetic simplicity, absence of endotoxins, and availability of well-characterized inducible systems have enabled controlled expression and delivery of heterologous antigens and therapeutic molecules. This review highlights recent advances in the use of genetically modified L. lactis for mucosal immunization, focusing on expression technologies, routes of administration, and immune mechanisms relevant to protection or tolerance. Preclinical studies demonstrate its capacity to induce both mucosal and systemic immune responses against diverse pathogens, underscoring its potential as a safe and versatile vaccine chassis. Remaining challenges include regulatory harmonization, biosafety concerns, and the need for standardized manufacturing and evaluation frameworks. Together, these developments position L. lactis as a promising candidate for next-generation mucosal vaccines and live biotherapeutic products.