AroA deficient Salmonella Typhimurium – More than an auxotrophic mutant

Recombinant attenuated Salmonella are believed to act as powerful live vaccine carrier able to elicit protection against many infectious agents. ?aroA exhibits auxotrophy for aromatic amino acids and is commonly used for attenuation. Interestingly, deletion of aroA dramatically increased virulence of the Salmonella. Detailed analyses demonstrate that Salmonella's physiology is significantly altered, most likely due to osmotic imbalance and stress. The result is a serious influence of lipid and amino acid turn over, possible increasing sensitivity to penicillin, complement and phagocytic uptake. In addition, in concert with other immunomodulating mutations, the phase of flagella expression is changed. Furthermore, virulence associated genes like arnT or ansB were affected. These alterations could explain the increased virulence. Thus, intravenous application of ?aroA Salmonella to mice significantly increased induction of pro-inflammatory cytokines. We also employed such bacteria in therapy against tumors and realized that ?aroA strains display an improved anti-tumor activity. Overall design: The samples of Salmonella Typhimurium Wild type strain and derivates (SF100 (?lpxR9 ?pagL7 ?pagP8), SF101 (?aroA), SF102 (?lpxR9 ?pagL7 ?pagP8 ?aroA)) were analyzed by RNA-seq. The control samples were cultivated in the LB medium until the exponential phase. Four biological replicas were pooled in pairs to get two replicas for RNA extraction, library preparation and sequencing. Tumor samples were collected from mice infected with Wt Salmonella and SF102. Bacterial RNA was extracted from single tumors. The tumor samples were split into two technical replicas for sequencing library preparation.