Attenuated and adapted strain of pseudomonas for delivering antigens

Abstract

A process for obtaining an adapted strain of Pseudomonas includes the following steps: deleting the genes ExoS, ExoT, aroA and lasl in an initial Pseudomonas strain cultivated in a LB medium; progressively cultivating this strain in a chemically defined medium based on a glucose minimal medium supplemented with magnesium and calcium; wherein the adapted strain presents the same toxicity and secretion capacities than the initial strain, and its doubling time when cultivated in the chemically defined medium is less than 60 minutes. An adapted strain is furthermore treated to become “killed but metabolically active.”

What is claimed is: 
     
         1 . A process for obtaining an adapted strain of  Pseudomonas , comprising:
 deleting genes ExoS, ExoT, aroA and lasl in an initial  Pseudomonas  strain cultivated in a LB medium;   progressively changing the culture medium from LB medium to a chemically defined medium comprising magnesium and calcium; and   selecting the adapted strains presenting a doubling time inferior to 60 minutes when cultivated in the chemically defined medium.   
     
     
         2 . The process according to  claim 1 , wherein the adapted strain is furthermore treated to become ‘killed but metabolically active’. 
     
     
         3 . An adapted strain of  Pseudomonas  such as obtained by the process according to  claim 2 , wherein the adapted strain presents the same toxicity and secretion capacities than the initial strain, and its doubling time when cultivated in the chemically defined medium is less than 60 minutes. 
     
     
         4 . An immunogenic composition comprising the adapted strain of  Pseudomonas  according to  claim 3 . 
     
     
         5 . Use of an adapted strain of  Pseudomonas  according to  claim 3 , for preparing a vaccine composition.