To approach the relationship between the srtF gene and the high pathogenicity of S. suis 2 05ZYH33, an isogenic knockout mutant of srtF was generated based on the principle of homologous recombination and confirmed by PCR, restriction analysis and reverse transcription polymerase chain reaction. The resulting mutant strain exhibited growth kinetics equivalent to those of the WT parent strain upon cultivation in standard laboratory used in our in vitro assays. A similar absence of difference between parent strain and mutant was observed when competition infection mice by the WT and mutant strains was evaluated. Taken together, these results suggest that srtF might in fact not critical for the full virulence of S. suis 2. It is to expect that future study carried out with S. suis 2 to verification the conclusions.
