Genetically Modified Lactic Acid Bacteria: a Promising Mucosal Delivery Vector for Vaccines

The advent of mucosal vaccines that target the primary entry points of many pathogens has revolutionized the field of immunology. Genetically modified lactic acid bacteria (gmLAB), which include genera such as Lactobacillus and Bifidobacterium, have emerged as promising vectors for delivering antigens to mucosal surfaces. These gram-positive, non-pathogenic microorganisms exhibit inherent probiotic properties, can survive through the gastrointestinal tract, and efficiently interact with the host immune system. Advances in genetic engineering have enabled the expression of a wide range of antigens in gmLAB that promote systemic and mucosal immunity. Studies have demonstrated that gmLAB-based mucosal vaccines can elicit both mucosal and systemic immune responses, providing protective immunity against specific pathogenic infections. In addition, gmLAB vectors offer good safety profiles, stability, and cost-effective production compared to traditional vaccine platforms. Recent studies demonstrated the potential of LAB vaccines in preventing infections caused by viral, bacterial, and parasitic pathogens and in immunotherapy for treating allergies and cancers. This review highlights the mechanisms underlying gmLAB-based mucosal vaccine delivery, current advancements, challenges, and prospects in recombinant mucosal vaccines.