Simultaneous identification of bacterial virulence genes by negative selection

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Science  21 Jul 1995:
Vol. 269, Issue 5222, pp. 400-403
DOI: 10.1126/science.7618105


An insertional mutagenesis system that uses transposons carrying unique DNA sequence tags was developed for the isolation of bacterial virulence genes. The tags from a mixed population of bacterial mutants representing the inoculum and bacteria recovered from infected hosts were detected by amplification, radiolabeling, and hybridization analysis. When applied to a murine model of typhoid fever caused by Salmonella typhimurium, mutants with attenuated virulence were revealed by use of tags that were present in the inoculum but not in bacteria recovered from infected mice. This approach resulted in the identification of new virulence genes, some of which are related to, but functionally distinct from, the inv/spa family of S. typhimurium.

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