The invention relates to the use of a compound that modulates the expression or activity of a microbial transcription factor in one of the following methods:a method for preventing or treating infection of a subject by a microbe, which method comprises administering the compound to a subject at risk of developing an infection such that infection of the subject is prevented or treated；a method for reducing virulence of a microbe, which method comprises administering the compound to a subject at risk of developing an infection with the microbe such that virulence of the microbe is reduced；a method for reducing virulence in a microbe, which method comprises administering the compound to a subject having a microbial infection such that virulence of the microbe is reduced.The invention also relates to a method comprising:(a) infecting or inoculating a nonhuman animal with a microbe, wherein the ability of the microbe to establish an infection in the nonhuman animal requires that the microbe colonize the animal；(b) administering a compound that modulates the expression or activity of the microbial transcription factor to the nonhuman animal； and(c1) determining the level of infection of the nonhuman animal, wherein the ability of the compound to reduce the level of infection of the animal indicates that the compound is effective at inhibiting microbial virulence； or(c2) determining the effect of the test compound on the ability of the microbe to colonize the animal, such that a compound for treating microbial infection is identified； or(c3) determining the effect of the test compound on the ability of the microbe to colonize the animal, such that a compound for reducing microbial virulence is identified.
