Contribution of MHC class I-dependent immune mechanisms induced by attenuated recombinant Salmonella typhimurium secreting superoxide dismutase to protection against murine listeriosis

A recombinant (r)Salmonella typhimurium aroA strain secreting the naturally non-secreted superoxide dismutase (SOD) of Listeria monocytogenes controls murine listeriosis dependent on 'transporter associated with antigen proce ssing' (TAP)-mediated immune mechanisms. TAP1-deficient mice (devoid of mus t CD8 T cells) vaccinated with this rSalmonella SODs strain succumbed to le thal L. monocytogenes challenge, whereas C57BL/6 mice were protected by thi s vaccine. Moreover, vaccination of H-ZI-A beta -deficient mice (lacking ma jor histocompatibility class (MHC) II molecules and thus devoid of mature C D4 TCR-alpha beta cells), of TAP1-deficient as well as of beta 2microglobul in-deficient mice (devoid of conventional CD8 T cells) with a sublethal dos e of L. monocytogenes and subsequent challenge with rSalmonella control or SODs strain revealed contribution of both MHC class I- and MHC class II-dep endent immune mechanisms to the control of secondary Salmonella infection. Finally, the clearance of rSalmonella SODs bacteria was achieved in TAP1-de ficient animals vaccinated with L. monocytogenes. Our data suggest a role o f TAP-dependent mechanisms in priming of protective immunity by rSalmonella micro-organisms secreting SOD. (C) 2001 Elsevier Science Ltd. All rights r eserved.