In vivo delivery of pPERDBY to BALB/c mice by LacVax® DNA-I and comparison of elicited immune response with conventional immunization methods.

The non-invasive food grade Lactococcus lactis (L. lactis) represents a safe and attractive alternative to invasive pathogens for the delivery of plasmid DNA at mucosal sites. We have earlier shown the DNA delivery potential of r-L. lactis harboring DNA vaccine reporter plasmid; pPERDBY in vitro. In the present work, we examined in vivo delivery potential of food grade non-invasive r-L. lactis::pPERDBY (LacVax® DNA-I) in BALB/c mice. Moreover, using EGFP as a model antigen, we also characterized and compared the immune response elicited by LacVax® DNA-I with other conventional vaccination approaches using protein and naked DNA immunization. The presence of antigen-specific serum IgG and fecal secretory IgA (sIgA) antibodies demonstrated in vivo DNA delivery and immune elicitation potential of the developed LacVax® DNA-I. As compared with intramuscular injection, oral delivery of pPERDBY via L. lactis resulted in a significantly rapid increase in IgG and higher sIgA titers, indicating the immunogenic and immunostimulatory properties of the LacVax® DNA-I. The needle-free immunization with LacVax® DNA-I led to increased production of IL-4, an indicator of Th2 screwed response. To the best of our knowledge, this report for the first time outlines comparison of orally administered LacVax® DNA-I with other conventional vaccination approaches.