Protective efficacy against tuberculosis of ESAT-6 secreted by a live Salmonella typhimurium vaccine carrier strain and expressed by naked DNA

We have constructed a recombinant (r) attenuated Salmonella typhimurium str ain which secretes ESAT-6 of Mycobacterium tuberculosis via the hemolysin s ecretion system of E. coli. Additionally, we have ligated ESAT-6 to differe nt commercially available mammalian expression systems for use as naked DNA vaccines. We studied protection against M. tuberculosis induced by vaccina tion with each of these constructs alone or in combination in mice. Vaccina tion with a single dose of r S. typhimurium secreting ESAT-6 reduced number s of tubercle bacilli in the lungs throughout the course of infection. The combined prime-boost vaccination did not considerably enhance protection. ( C) 2001 Elsevier Science Ltd. All rights reserved.