Figure 2From: Construction of Bordetella pertussis strains with enhanced production of genetically-inactivated Pertussis Toxin and Pertactin by unmarked allelic exchangeAllelic-exchange procedure. A: Double recombination events leading to the replacement of the S1 gene by a chloramphenicol resistance marker. B: Double recombination events leading to the re-insertion of the modified S1 gene in its original location.Back to article page