Patent ID: 6878516

Claim:
A process for the identification of a microbial gene encoding a gene product that is important to a microbe's ability to infect or sustain an infection in a mammal, which process comprises: infecting a plurality of mammals with a microbe that bas been genetically altered such that the amount of said gene product produced by said genetically altered microbe is regulated by a Tetracycline-Controllable Element (TCE); where said TCE is a gene regulatory system that controls the expression of the target gene product through its ability to modulate the function of said gene in response to said microbe's exposure to tetracycline, and where said TCE is comprised of a tetracycline-controllable transcription promoter polynucleotide sequence; where said genetically altered microbe also comprises a polynucleotide sequence encoding a tetracycline resistance protein; where said polynucleotide sequence encoding a tetracycline resistance protein is contained on a tetracycline resistance and repressor DNA cassette (TRRDC), said TRRDC comprising a tetracycline repressor gene and a tetracycline resistance gene; where said TCE is operably linked to both a first polynucleotide sequence encoding a reporter gene (RG) and a second polynucleotide sequence comprising a target gene (TG); exposing the plurality of mammals to tetracycline; once an infection with the genetically altered microbe is establish, removing the tetracycline exposure of a portion of the plurality of mammals, such that a first group of the plurality of mammals is exposed to tetracycline and a second group of the plurality of mammals is not exposed to tetracycline; and comparing the degree of infection, microbe levels, or survival rates of the mammals in the first group and the second group wherein a difference between the two groups of animals in the survival rates levels of microbes, or levels of infection present identifies the gene product as important to a microbe's ability to infect or sustain an infection in a mammal.