1 results
7 - In vivo identification, expression and function of Salmonella virulence genes
-
- By Helene Andrews-Polymenis, Department of Medical Microbiology & Immunology, 407 Reynolds Medical Building, Texas A&M University SHSC, College Station, TX 77843-1114, USA, Caleb W. Dorsey, Dept. Med. Microbiol. & Immunol., 407 Reynolds Medical Building, Texas A&M University SHSC, College Station, TX 77843-1114, USA, Manuela Raffatellu, Dept. Med. Microbiol. & Immonol., School of Medicine, University of California at Davis, One Shields Ave., Davis, CA 95616-8645, Andreas J. Bäumler, Department of Medical Microbiology & Immunology, School of Medicine, University of California at Davis, One Shields Ave., Davis, CA 95616-8645, USA
- Edited by Pietro Mastroeni, University of Cambridge
- Duncan Maskell, University of Cambridge
-
- Book:
- Salmonella Infections
- Published online:
- 04 December 2009
- Print publication:
- 09 February 2006, pp 173-206
-
- Chapter
- Export citation
-
Summary
INTRODUCTION
Any determinant that enables a Salmonella serotype to enter a host, to find a unique niche to multiply, to avoid or subvert the host defenses, to cause disease and to be transmitted to the next susceptible host may be considered a virulence determinant. Essential genes required for growth in standard laboratory medium are usually not included under this broad definition of virulence genes. The total number of virulence genes present in the Salmonella genome can be estimated by screening a bank of mutants generated by random transposon mutagenesis using an animal model of infection. The genome of Salmonella enterica serovar Typhimurium strain LT2 contains 4552 intact open reading frames (McClelland et al., 2001). Of these, approximately 490 genes are essential during growth in rich medium (Knuth et al., 2004). Thus, only the function of about 4062 genes is assessed when S. enterica serovar Typhimurium transposon mutants are generated and analyzed. Analysis of 197 randomly generated transposon mutants of S. enterica serovar Typhimurium for virulence in mice upon intra gastric infection identified 8 mutants that were more than 1000 fold attenuated (Bowe et al., 1998). Extrapolating to the actual number of intact genes present in the genome (4062 genes) this study suggests that mutations in approximately 165 S. enterica serovar Typhimurium genes result in attenuation of more than 1,000-fold in mice.