Abstract: In a comparative aspect, the functional state of inflammation effector cells in animals infected with various plasmid types of Yersinia pseudotuberculosis was studied. The metabolic activity of peritoneal exudate cells has been investigated in an experimental infection caused by four plasmid types of Y. pseudotuberculosis: type 82+: 48+, containing two plasmids pVM 82 and pYV; type 82+: 48- containing single pVM 82 plasmid; type 48+: 82- containing single pYV plasmid; plasmid-free type 48-: 82-. The parameters of enzyme activity (ATP-ase, 5'-nucleotidase, lactate dehydrogenase, myeloperoxidase) and the level of nitric oxide metabolites were determined. The variability of the metabolic activity of the cells in the inflammatory focus (peritoneal exudate containing neutrophils and macrophages) in infected animals has been established. In response to infection with Y. pseudotuberculosis strain containing two plasmids pYV and pVM82, the production of the nitric oxide metabolites, rather than the active forms of oxygen, had the primary importance in providing the bactericidal potential of phagocytes, compared to animals infected with a strain containing a single pVM82 plasmid. It was concluded that a special biological effect associated with the pVM 82 plasmid available in the Far Eastern strains of the causative agent of epidemic pseudotuberculosis (Far Eastern scarlet-like fever) was involved in the provision of predominantly nitroxide-dependent bactericidal mechanisms of innate immunity cells in this infection.Abstract: In a comparative aspect, the functional state of inflammation effector cells in animals infected with various plasmid types of Yersinia pseudotuberculosis was studied. The metabolic activity of peritoneal exudate cells has been investigated in an experimental infection caused by four plasmid types of Y. pseudotuberculosis: type 82+: 48+, containing...Show More