Construction of an E. coli-Leishmania shuttle vector

For many infectious diseases that still don’t have an effective vaccine, enhancing T cell immune response may be the key to solve this problem. Leijuvant represents a whole new perspective of adjuvant that uses Leishmania as an effective T cell stimulator. Leishmania is a parasite that specifically lives within macrophage, a professional antigen presenting cell (APC). As a potential vaccine adjuvant, Leishmania possesses many advantages, including APC recruitment, pattern recognition receptor activation, inflammasome activation, activation of MHC-presenting pathway, and most important of all, T cell activation. Genetically-engineered Leishmania that can be inactivated by light exposure acts as a safe carrier to deliver specific antigens to APCs for activation of T and B cells. Based on this concept, we established a new model system to generate antigen-specific Leishmania adjuvant-Leijuvant. Our ultimate goal is to introduce Leijuvant as an effective, safe, and antigen-specific adjuvant to the vaccine industry and the general public. For the beginning, we built a shuttle vector that can express proteins in Escherichia coli and Leishmania. We used this shuttle vector to express hemagglutinin of H1N1 influenza virus and ovalbumin in Leishmania. After drug selection, we analyzed protein expression of stable Leishmania transfectants by immunoblotting. The absence of hemagglutinin and ovalbumin expression suggests the importance of a 2.3-kb Leishmania intergenic sequence in building an effective shuttle vector.