Decreased Resistance of DeltasalKR to PMN-Mediated Killing 
Together with the wild type strain, DeltasalKR was subjected to PMN-mediated killing assays.
We found that the mortality rate of both strains (WT and DeltasalKR) increased coordinately with the extension of the co-culture time with PMN cells (Fig. 6).
However, DeltasalKR had a higher mortality rate than that of WT, which means that DeltasalKR was less able to resist killing by PMNs, key mediators of innate immunity.
This result may account partially, if not most of all, for the virulence loss in DeltasalKR.
