[Evaluation of the efficiency of external assessment of the quality of determining antibodies to hepatitis C virus in the network of screening laboratories].

A regional external quality assessment (EQA) system for determining anti-hepatitis C virus (HCV) was developed and introduced. For this, a control panel comprising 14 samples with anti-HCV and 6 samples without anti-HCV was tested in the reference laboratory of Moscow Infectious Hospital One. A total of 6 sessions were conducted with the participation of 8 laboratories. The regional EQA system covering a limited number of laboratories was shown to significantly improve the quality of detection of hepatitis C virus antibodies. The optimal multiplicity of sessions for the developed EQA system was ascertained to be once fortnight. It is possible to define the current rating of screening laboratories in the sensitivity criterion and to elaborate address organizational-and-methodic measures according to the results of control tests.

[Evaluation of the system for controlling the quality of the HBsAg detection in the system of screening laboratories]. / Otsenka sistemy kontrolia kachestva detektsii HBsAg v seti skriningovykh laboratorii.

The two-stage control system, ensuring the high quality of serological investigations in the network of screening laboratories in Moscow was developed and introduced into practice. At the first stage the entry control of the quality of the test system for the detection of HbsAg, coming to the screening laboratories, is made in the reference laboratory with the use of specially developed "representative" panels, as well as the test systems for comparison ("reference" test systems). Then "minipanels" are formed from specimens included into the "representative" panels, which are used for the evaluation of the quality of laboratory investigations made in the screening laboratories. The high quality of such system for controlling the quality of the detection of HBsAg in the screening laboratories of Moscow is shown.

[Propagation of hepatitis E virus in an endemic and nonendemic regions]. / Osobennosti rasprostraneniia virusa gepatita E v éndemichnom i neéndemichnom regionakh.

The role of hepatitis E (HE) in sporadic morbidity at an endemic territory (Southern Uzbekistan) and the incidence of anti-HEV in different populations of a nonendemic region (Russia) were evaluated. Antibodies to HEV were detected in 22.1% of patients with acute HE, including mixed infections (+ HA or HB), in the Dekhkanabad district of Kashkadarya region in 1993. The estimated incidence of acute HE was 51.7 per 100,000 population. Analysis of monthly incidence of acute HE demonstrated a seasonal pattern of the morbidity: more than 80% of total recorded cases occurred in August-September. These data indicate the presence of group HEV infections and an important role of this infection in the structure of acute viral hepatitis at the endemic territory. Anti-HEV were found in some population groups at a nonendemic territory: in free-of-charge blood donors in Surgut (4%), in patients with HIV infection (1.6%), and in medical workers in Moscow (1.1%).

[The affinity binding of staphylococci with immobilized human plasminogen]. / Affinnoe sviazyvanie stafilokkov s immobilizovannym plazminogenom cheloveka.

The phenomenon of the selective adhesion of staphylococci to immobilized human plasminogen was discovered and studied in the reaction of bacteriosorption. The study, made with S.aureus cells, strain Cowan 1, revealed that the degree of adhesion depended on the amount of immobilized protein and the time of its contact with bacterial suspension. The dose-dependent inhibition of adhesion with plasminogen and plasmin solutions, found to occur also with IgG, was demonstrated. Staphylococcal protein A did not inhibit adhesion. The plasminogen-binding receptor structure was shown to be highly sensitive to proteolysis, which is indicative of its protein nature.

[The binding of microorganisms isolated from patients with complicated forms of acute cholecystitis with immobilized proteins in the bacterial sorption reaction]. / Sviazyvanie mikroorganizmov, vydelennykh ot bol'nykh s oslozhnennymi formami ostrogo kholetsistita, s immobilizovannymi belkami v reaktsii bakteriosorbtsii.

57 strains of different microbial species, isolated from patients having complicated forms of acute cholecystitis, were studied with the use of the reaction of bacteriosorption on immobilized proteins: fibrinogen, fibronectin, gamma globulin, ovalbumin, etc. The reaction of bacteriosorption was positive with all 4 Staphylococcus aureus strains: they were adsorbed on fibrinogen, fibronectin and gamma globulin. Besides, 4 out of 18 Staphylococcus epidermidis strains were selectively adsorbed on fibronectin and 1 of these strains was adsorbed on ovalbumin, while 2 out of 15 Escherichia coli strains were adsorbed on ovalbumin. S. epidermidis strains studied in this work differed from 15 strains of the same species, isolated from the urine of patients and studied earlier, by their adsorption properties.

[Staphylococcal binding with immobilized proteins in the bacteriosorption reaction]. / Sviazyvanie stafilokokkov s immmobilizovannymi belkami v reaktsii bakteriosorbtsii.

The affinity binding of staphylococci with fibronectin (FN), fibrinogen (FG) and IgG was studied by means of the bacteriosorption test developed by the authors. For this purpose, the suspensions of staphylococci of the strains under study in physiological saline containing 0.1% of Tween-20 was applied in drops onto the areas of polystyrene Petri dishes sensitized with consecutive dilutions of FN, FG, gamma globulin (GL) and ovalbumin (control). The results of the test, manifested as spots formed by the adsorption of staphylococci, were evaluated by visual examination. The test showed that all 62 strains of coagulase-positive staphylococci (S. aureus) were adsorbed on immobilized FG and FN, and 49 of them (79%) were also adsorbed on immobilized GL. The specificity of adsorption was confirmed by negative controls and by the inhibition of the reaction with the solutions of 4 above-mentioned proteins. Out of 32 strains of coagulase-negative staphylococci (S. saprophyticus and S. epidermidis), 20 strains (62.5%) were not adsorbed on any of the proteins, and the remaining 12 strains were nonspecifically adsorbed on all 4 proteins. This new test is proposed for use as an auxiliary method for the identification and typing of micro-organisms.

[Assessment of the specific activity of commercial allergen preparations made of house dust in the bacteriosorption reaction: a comparison with the results of the radioallergosorbent inhibition test]. / Otsenka spetsificheskoi aktivnosti kommercheskikh preparatov allergenov iz domashnei pyli v reaktsii bakteriosorbtsii: sravnenie s rezul'tatami tormozheniia radioallergosorbentnogo testa.

The activity of the commercial batches of house-dust (HD) allergens was compared in the inhibition of the radioallergosorbent test (RAST) and in the direct bacteriosorbent test (BST), detecting IgG to the antigens by adsorption on the complexes of whole staphylococcal cells containing protein A. BST was made with rabbit antiserum to HD allergen. This antiserum inhibited RAST by 76% and, therefore, contained antibodies to most of the allergenic determinants of HD. At the same time, no significant correlation between the activity of 15 batches of HD allergen was revealed in RAST inhibition and in BST with the above antiserum. Nevertheless, the exhaustion of the antiserum with a batch of HD allergen showing low activity in RAST inhibition, but high activity in BST made it possible to obtain BST results significantly correlating with the data resulting from RAST inhibition in two series of experiments.

[Bacteriosorption reaction on a smooth surface for detecting antibodies and antigens]. / Reaktsiia bakteriosorbtsii na gladkoi poverkhnosti dlia vyiavleniia antitel i antigenov.

The solid-phase technique for the detection of antibodies and antigens has been developed and named the bacteriosorption test. The test is based on binding staphylococci containing protein A with the Fc-regions of IgG-antibodies attached to antigens immobilized on polystyrene. The possibilities of this technique have been analyzed with the use of diphtheria toxoid, house-dust allergen and homologous rabbit antisera. In the detection of antibodies the proposed test is not inferior to the passive hemagglutination test, and its sensitivity in the detection of antigens by the sandwich technique reaches 0.05-0.1 micrograms/ml. The specificity of the technique has been experimentally confirmed by the inhibition of the reaction with soluble antigen and staphylococcal protein A. The variability factor of the technique does not exceed 10%.

[Evaluation of the immunospecific activity of allergens prepared from house dust and the mite Dermatophagoides pteronyssinus in the bacteriosorption reaction on a flat surface]. / Otsenka immunospetsificheskoi aktivnosti allergenov domashchei pyli i kleshcha Dermatophagoides pteronyssinus v reaktsii bakteriosorbtsii na ploskoi poverkhnosti.

The content of protein A-reactive IgG to allergens prepared from house dust and D. pteronyssinus was determined in the sera of 4 immunized rabbits, 10 sensitized and hyposensitized guinea pigs and 37 treated and untreated allergic patients by means of the previously developed bacteriosorption test (BST). The sensitivity of the test for the determination of allergen-specific antibodies was 50-100 ng/ml. This test was shown to permit the detection of IgG in the sera of immunized, sensitized and hyposensitized animals, as well as in the sera of some treated and untreated patients. The antigenic similarity of both allergens was confirmed. Three batches of D. pteronyssinus allergen, standardized as to the content of protein nitrogen, differed in their immunospecific activity in BST with one of the rabbit sera and with the set of the patients' sera. The covalent immobilization of house-dust allergen on polystyrene by means of water-soluble carbodiimide gave no advantages in BST in comparison with adsorption immobilization in alkaline carbonate-bicarbonate buffer.