Fig. (4) Attenuation of S. equi virulence by vicK deletion and protection of mice against wild-type S. equi infection conferred by preceding ΔvicK infection. Groups of 8 CD-1 mice were inoculated subcutaneously (A) and intranasally (B) with 1.1 x 108 cfu of each strain, and survival rates were determined daily. Panel A also includes the results of the subcutaneous infection with 1.5 x 108 cfu of the wild-type strain on the 7 mice survived from the subcutaneous vicK infection (the open circles)