Isolation and characteristics of the biological and genetic properties of neamin-resistant mutants of Salmonella typhimurium and Salmonella dublin candidates for vaccine creation

Mutants, resistant to neamine and spectinomycin, have been isolated from S. typhimurium and S. dublin highly virulent strains. The neamine-resistant mutants can be divided into 3 classes in accordance with their sensitivity to streptomycin: sensitive, resistant to low and high concentrations of this antibiotic. The transduction analysis with the use of bacteriophage P 22 has revealed that the spectinomycin-resistant mutations under study are spc A mutations, while the mutations leading to resistance to neamine in class Near Strr 500 are nea B mutations. The mutation leading to resistance to spectinomycin (spc A) has been found to produce no changes in the virulence of salmonellae in the intraperitoneal infection of mice. The mutations leading to resistance to neamine and streptomycin (nea B and str A) have been found to decrease virulence.     

Mobilization of phase I plasmid in Shigella sonnei and stability of its inheritance in rough strains of Shigella and Escherichia

The plasmid pSS120, determining the synthesis of species specific I phase antigen of Shigella sonnei is mobilized for genetic transfer into E. coli K12 recipient cells with the frequency 12-41%. The frequency depends on the type of mobilized plasmid and recipient strain. The I phase antigen is normally expressed in II phase recipient cells and in E. coli cells. During mobilization pSS120 forms cointegrates representing a recombinant of mobilizing and mobilized plasmids DNA. The study of pSS120 inheritance stability has shown the plasmid to be unstable during culturing of bacteria and to be partially lost from the parent Shigella sonnei strains as well as from the "hybrid" transconjugants obtained. The 60 Md plasmid present in the donor strains of Shigella sonnei is prone to structural fragmentation particularly expressed in Shigella sonnei/E. coli hybrids.     

Dynamics of enterobacterial multiplication in a mouse model of intraperitoneal infection in the presence of iron cations as dependent on the availability and type of K antigens

In this work the results of research on the influence of iron cations on the characteristics of the infectious process caused by different enterobacteria (Shigella sonnei, Shigella flexneri, Escherichia coli) are analyzed. In the experimental intraperitoneal infection of mice in the presence of saccharose and iron cations S. sonnei in phase I showed the decrease of 1g LD50 by 3-4 orders, while S. flexneri in the S-form, by not more than 1 order. The absence of correlation between the virulence of the Shigella species used for comparison, as determined in the keratoconjunctival test, and their behavior in vitro in the presence of iron was revealed. E. coli reference strains synthetizing (according to the nomenclature of I. Orskov et al.) "true" K-antigens (K1, K10) or "not true" ones (K8, K9, K27, K57) also showed different virulence in the experimental infection used in this research: the behavior of the former group corresponded to that of S. sonnei in phase I, the latter group occupied the intermediate position between the former group and S. sonnei on one hand and S. flexneri on the other hand. The sharp drop of 1g LD50 after the injection of S. sonnei in phase I in combination with iron cations can be attributed to differences in the characteristics of bacterial surface structures with antiphagocytic function and indicates that the species-specific antigen of S. sonnei in phase I should be classified with K-antigens. The experimental intraperitoneal infection of mice in the presence of trivalent iron cations can be used for making a tentative judgement on the presence of K-antigens in enterobacteria.     

Immunoenzyme determination of human granulocyte-macrophage colony-stimulating factor using monoclonal antibodies

A set of seven hybridomas producing monoclonal antibodies (MAbs) to the human recombinant granulocyte-macrophage colony-stimulating factor (GM-CSF) was obtained. The properties of the monoclonal antibodies were characterized, and pairs of MAbs specific to different non-overlapping epitopes of GM-CSF were identified. A sensitive and simple method of two-site ELISA for GM-CSF was developed on the basis of two MAbs. According to this method, one MAb is absorbed onto a microtiter plate and another is labeled with biotin and used for the detection of GM-CSF bound to the first MAb. MAb labeled with biotin, in its turn, was visualized with the streptavidin-horseradish peroxidase conjugate. The sensitivity of this test was no less than 0.5 ng/ml, and a linear dose-response relationship was observed within a concentration interval from 0.5 to 32 ng/ml. No cross-reactivity was found with human tumor necrosis factor-alpha, granulocyte colony-stimulating factor, interleukin-2, or interleukin-3 in this test system.     

Digital volume tomography in the diagnosis of the surgical anatomy of the frontal recess area

Frontal recess anatomy can be very complex, with accessory cells, such as frontal bulla, agger nasi, suprabulla, and frontal ethmoidal (Kuhn) cells, which may lead to obstruction of the frontal sinus. Digital volume tomography of paranasal sinuses used in this investigation revealed the rate of types of development of various anatomic structures and their correlation with frontal sinusitis in patients with (a study) and without the latter (a control group).     

Biological activity of extracts isolated from a virulent strain of Sh. flexneri grown in the presence of calcium ions]

The authors carried out a comparative study of the genetically connected Sh. flexneri cultures (3 virulent strains, 3 clones of an avirulent mutant selected in the flux of an oblique light from the virulent strain, and lac+ Kcp A-hybrids obtained by crossing the initial virulent cultures with the E. coli K12 Hfr strains). The absence of any correlation between the virulence of the strains under study and the lipopolysaccharide (by rhamnose) content in the extracts from them in growing the cultures in the presence of calcium ions was noted. Toxicity of the extracts from the virulent cultures was demonstrated on a model of developing chick embryos. No such property was possessed by the extracts from avirulent strains. The extracts from the virulent cultures in nontoxic doses possessed the capacity to decrease LD50 of shigella strains used for the infection. The biologically active factor determined in the extracts from the virulent cultures apparently was not lipopolysaccharide.