Growth of DeltavicK in THY and Rabbit Blood 
The growth curve of the DeltavicK mutant in THY displays a longer early growth phase and smaller slope in the exponential growth phase than that of the parent strain (Fig. 2A), indicating that the vicK deletion detrimentally affects S. equi growth.
The effect of the deletion on S. equi growth in blood was also examined.
The wild-type and DeltavicK S. equi strains were inoculated into 1 ml heparinized rabbit blood at an inoculum of approximately 20,000 cfu.
The samples were incubated for 4 h, and the numbers of the bacteria in the samples and inocula at time zero were determined by plating.
The growth factors, the ratio of cfu in the sample at 4 h over cfu at time zero, were 250 and 66 for the wild type and DeltavicK strains, respectively (Fig. 2B).
Thus, the DeltavicK mutant has significantly reduced ability to grow in rabbit blood (P <0.0001).
