The growth rate of the vegetative forms and the recultivation rate of the uncultivable forms of Salmonella isogenous strains, one of these strains carrying mutation in gene pqi, were studied. The multiplication rate of the vegetative and uncultivable forms of Salmonella control strain in the spleen of infected animals at the initial stages of the infectious process was shown (in vivo) to be considerably accelerated after the preliminary incubation of the culture with cytokine (tumor necrosis factor). The multiplication rate, in vivo and in vitro, of Salmonella vegetative and uncultivable forms with mutation in gene pqi did not change after the incubation of the cells with cytokine, which is indicative of an important role played by the product of this gene in the process of the interaction of bacteria with cytokines. The full nucleotide sequence Salmonella gene pqi was determined.