Changes in the metabolism of innate immune cells of homoithermic animals infected with dormant forms of Yersinia pseudotuberculosis

Abstract

Under the influence of unfavorable environmental factors, microorganisms pass into a viable, but uncultivated state and form a dormant (dormant) cellular phenotype, characterized by a lack of growth and metabolic activity. Dormant forms of bacteria are not detected by traditional microbiological methods, but they play an important role in the development of protracted and chronic infections in animals and humans. Purpose of the study: to characterize the experimental infectious process in warm-blooded animals, induced by the dormant phenotypes of Y. pseudotuberculosis, and to evaluate changes in the activity of the enzyme systems of inflammatory effector cells. For the study, bacteria were taken from a culture stored under static conditions for 10 years in a test tube under a layer of petroleum jelly at a temperature of 4–6 °C. Ultrastructural features of dormant cell forms were confirmed by transmission electron microscopy. The viability of dormant cells was assessed by the molecular genetic method (PCR). The absence of reproductive activity of the dormant phenotypes of Y. pseudotuberculosis was checked by repeated inoculations in LB broth, Endo and Serov›s media, and incubation at temperatures of 4–6, 22–24 and 37 °C. Further, the activity of the enzyme systems of cells of the inflammatory process effectors in vivo was investigated. During the experimental infection, the animals showed a gradual increase in the number of inflammatory effector cells. The prevailing number of neutrophils (65–70 %) on days 14–21 of infection indicated a developing inflammatory process. Reversion of the dormant form of Y. pseudotuberculosis in vivo and the development of an inflammatory process in the cells of the peritoneal exudate of infected animals inhibits the activity of the oxygen- and nitroxide-dependent bactericidal systems, as evidenced by the low values of lactate dehydrogenase, myeloperoxidase and nitric oxide. Thus, the data obtained indicate the possibility of reversion of the dormant forms of Y. pseudotuberculosis into vegetative forms 21 days after infection. On the part of the cells of innate immunity, modulation of the activity of intracellular enzymes, aimed at the induction of antimicrobial protection, was revealed.