[Enzyme immunoassay for the determination of hexestrol in meat].

An indirect competitive enzyme-linked immunosorbent assay (ELISA) of hexestrol (HES), an antibiotic forbidden for use in livestock farming, has been developed. Conditions of ELISA have been optimized by varying the concentrations of the coating conjugate (HES-ovalbumin), anti-HES antiserum, casein, and Tween 20. In the absence of Tween 20 in the reaction mixture, the detection limit (IC10) equaled 0.01 ng/ml, IC50 equaled 0.17 ng/ml, and the working range (IC20-IC80) equaled 0.03-0.86 ng/ml, while, in the presence of 0.05% Tween 20, these values equaled 0.05 ng/ml, 2.9 ng/ml, and 0.26-32.0 ng/ml, respectively. Standard deviation of the analysis results did not exceed 5.4%. If ELISA was performed in the absence of detergents, the recovery value upon HES determination in spiked beef samples ranged from 74 to 147%.

[The hydrophobicity of Streptococcus pyogenes as a possible marker of its virulence]. / Gidrofobnost' Streptococcus pyogenes kak vozmozhnyi marker ego virulentnosti.

The hydrophobicity of 366 S. pyogenes cultures isolated from the pharynx of tonsillitis and scarlet fever patients and healthy children, as well as museum strain of type M29, was studied. The study revealed that the hydrophobicity of cultures isolated from scarlet fever patients exceeded that of cultures isolated from healthy carriers and tonsillitis patients. Among S. pyogenes cultures isolated in cases of prolonged carriership a considerable proportion of highly hydrophobic cultures was detected, which was probably indicative of an important role played by the hydrophobicity of streptococci in retaining them on the barrier epithelium. This was confirmed by the presence of correlation between the hydrophobicity of culture of S. pyogenes, type M29, and its adhesion to the fibronectin receptor and HEp-2 cells. For S. pyogenes of type M6, epidemic in the group of children under observation during the period of 1987-1988, the values characterizing its hydrophobicity were registered which significantly exceeded average hydrophobicity values. At the period of a rise in morbidity S. pyogenes cultures were characterized by significantly higher hydrophobicity. The variability of the hydrophobicity index and its relationship with the dissociation of cultures were established. The hydrophobicity index may be used as one of the virulence markers of S. pyogenes strains.

[The diagnostic and prognostic significance of the indices of the immune response to streptococcal group A antigens in rheumatism]. / Diagnosticheskoe i prognosticheskoe znachenie pokazatelei immunnogo otveta na antigeny streptokokka gruppy A pri revmatizme.

Serum samples obtained from 33 patients with acute rheumatic fever (ARF), 60 patients with rheumatic heart disease (RHD) and 30 adult healthy persons have been studied. Antibodies to streptococcal A polysaccharide (SAP) and lypoteichoic acid (LTA) were examined by ELISA, to streptolysin O by standard technique. SAP antibodies in high titers persisted from 5 to 12 months in ARF and rheumatic carditis patients especially when RHD was developing. High titers of antibodies to LTA and SLO persisted for 3 months since ARF onset, then fell (p < 0.05). ELISA proved sensitive in determination of antibodies to SAP and LTA. Its combination with determination of the titers to SLO antigens confirmed Streptococcus A infection involvement in emergence of ARF in all the cases including insidious or late-onset carditis and chorea. High levels of antibodies to SAP and LTA were more frequently detected in patients with RHD than in healthy persons (p < 0.001). Correlation between frequency of high levels of antibodies to SAP and bicillin 5 or erythromycin administration, duration of RHD was not established.

[Streptococcal group A carriage: new data on the characteristics of the biology of the causative agent and of the immune response of the host]. / Nositel'stvo streptokokka gruppy A: novye dannye po kharakteristike biologii vozbuditelia i immunnogo otveta khoziaina.

Carriership of group A streptococcus (A-STR) was registered with significantly greater frequency among children of preschool and early school age (29.8%) than among adults (4.0%). Cultures of A-STR isolated from carriers were characterized by their low capacity for secreting erythrogenic toxin of type A (ET-A), lipoteichoic acid and by lower content of surface proteins than those isolated from tonsillitis and scarlet fever patients. Highly hydrophobic strains of A-STR prevailed in long-time carriers and patients. Elevated immunological characteristics for group-specific polysaccharide A and ET-A were more frequently detected in children than in adults, which correlated with frequency of A-STR carriership in these groups and the capacity of the infective agent to produce ET-A. Some specific features in the character of humoral immune response in carriers, manifested mainly by defects of local immunity (a low level of SIgA to polysaccharide A), were established.

[Preparation of immune sera to group A streptococcus lipoteichoic acid]. / Poluchenie immunnykh syvorotok k lipoteikhoevoi kislote streptokokka gruppy A.

A method is described for the preparation of sera highly active in reactions with Group A Streptococcus lipoteichoic acid. Ultrasound-destroyed biomass of Streptomyces levoris K-3053 strain is used as the antigen. This strain was isolated in studies of soil Streptomyces; it contains sufficient amounts of nonglycosylated glycerolteichoic acid of the first-third types, that is identical in structure to polyglycerophosphate skeleton of Group A Streptococcus lipoteichoic acid.

[Structure and properties of lipoteichoic acid of group A Streptococcus type M 29]. / Stroenie i svoistva lipoteikhoevoi kisloty streptokokka gruppy A tipa M 29.

Lipoteichoic acid (LTA) of group A streptococci, type M 29 was studied. Chemical and 13C NMR spectroscopic analysis showed that the polymer contained poly(glycerophosphate) chain consisting of 12-14 glycerophosphate elements united by the 1----3 type phosphodiether bond and diglucosylglyceride. Oleic, stearic, palmitic and palmitoleic fatty acids predominated in the polymer composition. The content of the fatty acids amounted approximately to 2 per cent of LTA dry weight. The poly(glycerophosphate) chain contained 6-7 ether linked alanyl moieties. The results of the LTA biological study were analyzed in comparison to the data on a previous study of antitumor and cardiotoxic properties of teichoic acid from Streptomyces levoris K-3053 which is structurally close to the LTA hydrophilic moiety. It was assumed that the molecule negative charge had an effect on the cardiotoxic and antitumor activity.

[Comparative study of cell walls of group A Streptococcus and its non-adhesive phosphomycin-resistant mutant]. / Sravnite'lnoe izuchenie kletochnykh stenok streptokokka gruppy A i ego neadgezivnogo fosfomitsinrezistentnogo mutanta.

The cell wall composition of nonadhesive fosfomycin-resistant mutant of group A streptococcus and highly adhesive wild strain have been studied. The cell wall of the mutant nonadhesive strain contained significantly reduced amounts of lipoteichoic acid and surface proteins as compared to the wild strain, did not contain surface lipoteichoic acid, and, possibly, differed in peptidoglycan-polysaccharide bonding. No differences in the qualitative carbohydrate composition of the cell walls were found. The amino acid composition of the cell walls of these microorganisms differed only in alanine content, which correlates with the reduction of lipoteichoic acid content in the mutant strain. The structural similarity of peptidoglycans of the two strains is demonstrated.

[Hydrophobic quality and the level of surface proteins in the cell wall of cultures of Streptococcus pyogenes isolated from clinically healthy children from an organized collective]. / Gidrofobnos't i kolichestvennoe sederzhanie poverkhnostnykh belkov kletochnoi stenki ku'ltur Streptococcus pyogenes, vydelennykh ot klinicheski zdorovykh detei v organizovannom kollektive.

The Str. pyogenes cultures isolated from clinically healthy children were found to have different hydrophobic properties and quantities of surface cell wall proteins, and to exhibit pronounced variability in these signs in time. Most studied cultures lacked a correlation between their hydrophobic properties and the quantity of surface proteins of the cell wall.

[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.

[Structure of teichoic acid of a poly(glycerophosphate) nature from Streptomyces levoris K-3053 and its biological properties]. / Struktura teikhoevoi kisloty poli(glitserofosfatnoi) prirody Streptomyces levoris K-3053 i nekotorye ee biologicheskie svoistva.

The wall teichoic acid from S. levoris was studied. It is a poly(glycerophosphate)polymer consisting of 15-20 nonsubstituted glycerophosphate units coupled by the phosphodiether bonds according to the 1, 3 type. It was shown that the acid had antitumor activity and high cardiotoxicity evident from a clear-cut negative ionotropic effect on the cardiac papillar muscle in dogs.

[Comparative study of lipoteichoic acid from Streptococcus pyogenes type 29 isolated by different methods]. / Sravnitel'noe izuchenie lipoteikhoevoi kisloty Streptococcus pyogenes tip 29, vydelennoi razlichnymi sposobami.

A comparative study of lipoteichoic acid preparations extracted from Streptococcus pyogenes with cold and hot phenol and trichloracetic acid was made. The most delicate way for isolation of lipoteichoic acid from the given microorganisms is cold phenol extraction.