Figure 3. Negative selection of the STM strains.
(A) Detection of the attenuated STM strains. The same input pool #3 was used to infect the middle ears of chinchillas or nasopharynx of mice in the 2nd round screen. The animals were sacrificed 3 days post infection to recover the bacteria (output pool) from the middle ears (chinchillas) or nasopharynx (mouse). The input and output pools were compared by PCR amplification and agarose gel electrophoresis. Pound signs (#) and asterisks (*) indicate the mutants that were missing in the output pools from the middle ear and nasopharynx, respectively. (B) Schematic representation of the STM strains identified in the 2nd round screen. The red and yellow colors indicate the total numbers of the mutants that were attenuated only in the middle ear infection or nasal colonization, respectively. The mutants attenuated in both models are represented by blue color. (C) Schematic representation of the genes identified in the 2nd round screen as in (B).