[An immunological analysis of bacterial persistence in the bone marrow].

A method for the evaluation of bacterial persistence in the bone marrow in association with particular clonogenic target cells was developed. The method was based on the negative selection of cells expressing microbial antigens after treatment with hyperimmune antiserum specific to a given infective agent and the subsequent quantitation of target cells thus eliminated in appropriate assays. Using this approach, we demonstrated that Mycoplasma arthritidis and L-forms of Streptococcus strain L-406 were capable of persisting in murine bone marrow in close association with CFUs-7 (a subpopulation of hematopoietic stem cells) for at least several months after experimental infection.

[Mutations in Francisella tularensis, decreasing the virulence of these bacteria and leading to a change in the immune response upon infection of experimental animals with them].

The research was aimed at isolation of Francisella tularensis mutants possessing the decreased virulence for experimental animals and mediating the changes in the animal immune response. A number of spontaneous and induced mutants of the American and European subtypes of Francisella tularensis were selected for antibiotics resistance or detergent sensitivity. All the obtained mutants have the decreased virulence and differ in their ability to induce the protective antitularemia immunity or ability to induce the humoral immune response in the laboratory animals.

[Detection of tularemia pathogens in patients with the use of an immunofluorescence reaction].

For the first time three cases of the detection of Francisella tularensis, made by means of the direct immunofluorescence test in the fluid obtained from punctured buboes or in purulent matter taken from patients with the ulcerous bubonic form of tularemia, are presented. The simplicity of the test and its capacity of yielding rapid results make it possible to recommend this test, together with other diagnostic methods, for the clinical diagnosis of tularemia.

[Delayed type hypersensitivity reaction in the pathogenesis and formation of immunity in tularemia infections in mice].

As a result of our studies, strain differences in the sensitivity of CBA and BALB/c mice to partially attenuated Francisella tularensis strain have been revealed. Relationship between the increased migration of lymphocytes to the liver and lymphoid organs and the intensive development of cell-mediated immunity reactions has been shown. An important role of local reactions (the skin at the site of the inoculation of F.