[Isolation or group B streptococci defective for the type antigen Ia by transposon-mediated mutagenesis]. / Poluchenie streptokokkov gruppy B, defektnykh po tipovomu antigenu Ia, metodom transpozonnogo mutageneza.

Transposon-mediated mutability has been used to isolate the isogenic strains of the group B serotype Ia streptococci with the mutations in the genes coding for the production of capsular antigen. The transconjugants have lost the ability to bind type Ia antiserum as demonstrated by immunoblotting technique. The loss of type-specific antigen by the strains has resulted in a dramatic decrease in virulence for mice while the absorbtion indexes of transconjugants increased 2-3 fold. The mutant clones deficient in capsule expression had the increased buoyant density in the percoll gradient as compared with the parent strains of group B. The stable mutants impaired in ability to produce the polysaccharide capsule on the cell surface were obtained as a result of site-specific insertion of transposon Tn916 into the genome of group B serotype I streptococcus.

[Dynamics of early morphologic shifts in the bronchopulmonary system in intranasal infection of mice with streptococcus group B]. / Dinamika rannykh morfologicheskikh sdvigov v bronkholegochnoi sisteme pri intranazal'nom zarazhenii myshei streptokokkom gruppy B.

When mice are intranasally infected with avirulent and virulent B streptococci, one may single out 2 phases of microbe interaction with bronchopulmonary tissue: 1) streptococcal adhesion, epithelial detachment and causative agent phagocytosis occur within the first 2 hours; 2) hematogenic phagocytes are involved in the process 5 or more hours later. Unlike avirulent streptococci, virulent ones frequently lead to the formation of destructive foci and are less actively phagocytized. On infection with avirulent strain, the microbes seed from the lung during 24 hours. The phagocytotic index and mean alveolar macrophage destruction values are in excess of the similar values seen in polymorphonuclear leukocytes, becoming lower on day 6 of postinfection.

[Comparative aspects of adhesion of group A and B streptococci to human epithelium]. / Sravnite'lnye aspekty adgezii streptokokkov grupp A i B k épiteliiu cheloveka.

The international and original research data on the adhesion of group A and B streptococci are over-viewed. Based on the conducted studies, a conclusion has been drawn on the polyfactor pattern of pathogenic streptococci adhesions. The polyfactor pattern of adhesion is manifested in (a) different ranges of tissue sensitivity to streptococci adhesion, (b) a correlation between the adhesiveness and particular phenotypes (M(+)-M-; OF(+)-OF- in group A streptococci, TSA(+)-TSA- in group B streptococci), (c) different sensitivity of adhesives to proteolytic enzymes, and (d) interaction with fibronectin. M-protein was found to be involved in specific pyogenic streptococcal adhesion to the pharyngeal epithelium, which opens up new vistas for the search of approaches to the prevention of mucosal colonization. The participation of lipoteichoic acid (LTA) in group A and B streptococci adhesion in different tissues was shown The involvement of proteins in group B streptococcal adhesion was suggested by indirect evidence, which needs to be confirmed by direct isolation of an adhesive. It is suggested, that different quantitative combinations as well as structural organization of protein complexes and LTA in the streptococcus cell wall may determine the strain and species specificity of pathogenic group A and B streptococci interaction with host tissues.

[Biological properties of Streptococcus group B: the interrelations of the virulence in mice, the adhesion to human epithelial cells and the production of type-specific antigen]. / Biologicheskie svoistva streptokokkov gruppy B: vzaimootnosheniia mezhdu virulentnost'iu dlia myshei, adgeziei k épitelial'nym kletkam cheloveka i produktsiei tipospetsificheskogo antigena.

The results presented in this work confirm the possibility of selecting the subpopulations of group B streptococci by the passage of these microorganisms through mice. This process was accompanied by the accumulation of cells with a high level of type-specific antigen (TSA). The passage of group B streptococci in the presence of type-specific antibodies led to the selection of avirulent microorganisms with low TSA production and high adhesiveness. These data may be considered to be the indirect evidence of the screening effect of TSA contained in the capsule of group B streptococci with respect to the ligand structures of these microbes. This suggestion is confirmed by the behavior of the variants of group B streptococci, obtained in the course of this investigation, on virus-infected tissue when TSA+ strains lost their ability to recognize viral polypeptides serving as receptors for TSA- variants of the streptococci.

[Effect of the influenza A virus on the sensitivity of mice to infection caused by Streptococcus group B]. / Vliianie virusa grippa A na chuvstvitel'nost' myshei k infektsii, vyzvannoi streptokokkami gruppy B.

Study of the capacity of group B streptococci for causing the development of infection in mice has revealed the virulence of the cultures for mice to be determined by the serovar of the streptococcus, the infective dose, and the amount of type-specific polysaccharide. Under the conditions of mixed viral-bacterial infection, influenza A virus was shown to influence the development of bacterial infection in the animals in two ways: to increase the virulence of an avirulent strain and to decrease the pathogenicity of a virulent one in streptococcal monoinfections. Simultaneously with viral infection, the stimulation of the multiplication of an avirulent strain in the lungs of mice was observed, while in the control groups of the animals the elimination of bacteria from the lungs was registered. No additional accumulation of the infective virus in the lungs of mice in the presence of streptococci was found.

Adherence of vaginal and pharyngeal strains of group B streptococci to human vaginal and pharyngeal epithelial cells.

In vitro tests for adherence to human vaginal and pharyngeal epithelial cells were used to study the problem of tissue-specific tropism in group B streptococci (GBS). Twenty-two vaginal or pharyngeal clinical isolates of GBS (serotypes Ia, Ib, II, and III) were used. No significant differences in adherence to vaginal and pharyngeal epithelial cells were found between GBS from both sources: statistical analysis furnished no evidence for tissue-specific tropism. Serotype III vaginal GBS adhered better to vaginal and pharyngeal epithelial cells than did serotype III GBS strains isolated from the pharynx. However, pronounced differences in the level of adherence were found among strains of the same serotypes and from the same sources. Thus, the results obtained suggest that differences in adherence may rather be strain-dependent that type-dependent.

The adhesin structures involved in the adherence of group B streptococci to human vaginal cells.

The adherence of group B streptococci (GBS) of serotypes Ia, II and III to human vaginal cells was studied in vitro. The adherence was not dependent on the viability of bacteria; killing of GBS by UV irradiation or glutaraldehyde treatment did not inhibit the adherence. Killing of GBS by heating to 56 degrees C for 1 h led to a pronounced decrease of adherence, demonstrating the thermosensitivity of the GBS structures involved. The protein nature of these structures was proved by a significant reduction of adherence after pretreatment of GBS with trypsin or pepsin. Pretreatment of GBS with sialidase had no influence on the adherence. Such a pretreatment of vaginal cells caused an increase of adherence showing that the receptors on epithelial cells may be partly masked by sialic acid.

[Adhesion of group B streptococci to vaginal epithelial cells]. / Adgeziia streptokokkov gruppy B na kletkakh vaginal'nogo épiteliia.

The work presents the results of studies on the optimum and standard conditions for the in vitro determination of the adhesiveness of group B streptococci with epithelial cell suspensions. Vaginal epithelium has proved to be the most convenient and adequate system for studying the adhesiveness of group B streptococci. The optimum infective dose of these bacteria has been found to range from 50 to 200 cocci per cell. The characteristics of the adhesion of group B streptococci to vaginal epithelium are highly reproducible and exhibit low dependence on the time of the incubation of the bacteria with epithelial cells; fluctuations in the adhesiveness of the cultures in the definite range of pH shifts are seemingly determined by the serotype of the strains.

[Streptococcus group A resistance to tetracycline: its spread and transduction]. / Ustoichivost' streptokokkov gruppy A tetratsiklinu: rasprostranennost' i transduktsiia.

The study on antibiotics resistance of group A streptococci isolated in 1977 showed that the number of the antibiotic resistant strains had significantly increased as compared to the data of 1960. High percentage (53%) of the cultures with multiple resistance was noted. It was observed that the number of the streptococcal cultures resistant to erythromycin and chloramphenicol decreased while the number of the strains resistant to tetracyclines increased. The level of resistance to tetracycline increased more than 2 times from 1960 and in some cases reached 125 and 250 gamma/ml. The wide spread of tetracycline resistance was evident of the presence of the mechanism of the marker transduction. Possible transduction of this feature was studied. Microbe-free phagolysates obtained by induction with UV-light from the strains with multiple antibiotic resistance were used as the donor material in the experiment on transduction. Principal possibility of transducing resistance to tetracycline from 2 donors to 4 recipients at a frequency of 10(-6) was shown.