Immune response to Streptomyces lividans in mice: a potential vaccine vehicle against TB

The potentialities of Streptomyces lividans 1326 as new live vaccine vehicle strategy have been evaluated. Immunization of mice with the Streptomyces mycelium induced high levels of specific antibodies against proteins released in the culture supernatant of the analyzed strain. Splenocytes from the Streptomyces-immunized animals were able to secrete high levels of IFN-γ (2103.9 pg/mL) and to proliferate in vitro on stimulation with proteins released by Streptomyces. The analysis of cross-reactivity against M. tuberculosis secreted proteins showed that the immunization of mice with Streptomyces led to a comparable level of cross-reacting antibodies as in the BCG immunized mice. Similarly sera antibodies from Streptomyces immunized group recognized whole BCG cells to the same degree as antibodies raised against BCG reacted with Streptomyces mycelium, indicating that these two actinobacteria cross-react immunologically. The Streptomyces lividans strain was highly immunogenic in mice showing an enduring Th1-dependent immune response. This is the first report demonstrating the potential of Streptomyces as an attractive vehicle for developing a live TB vaccine.