[Polymerase chain reaction in the diagnosis of tuberculosis].
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DNA, Bacterial↗
Biomedical subjects
G R Matsevich
Publications and source records attributed to G R Matsevich.
Inhibition of human immunodeficiency virus type 1 (HIV-1) penetration into target cells by synthetic peptides mimicking the N-terminus of the HIV-1 transmembrane glycoprotein.
To investigate the mechanism of action of the 22-amino-acid HIV fusion peptide on HIV infection, we studied its influence on virus adsorption and HIV-induced syncytium formation. The effect of the peptide preparations on the synthesis of viral antigens in HIV-infected cell cultures was determined by antigen capture assay, and the inhibition of proviral DNA synthesis was detected by hybridization with a HIV-specific oligonucleotide probe after PCR amplification. Fusion peptides inhibited HIV-induced syncytium formation and antigen production in lytic infected cells, and this effect was increased in conjugation with bovine serum albumin or with synthetic net-charged polymer by its C-terminus. The association of peptide with carrier by N-terminus, or with positive-charged polymer or gelatin completely abolished its effect on HIV infection. No peptide preparations influenced HIV-1 chronically infected cells. Because peptide preparations blocked the HIV-specific DNA synthesis 2 hr after infection without influencing virus adsorption and reverse transcription, we concluded that the block of infection occurred during the penetration of virions through the cell membrane. On the basis of results obtained we propose that our peptide preparations could be used for anti-HIV chemotherapy. The possibility of the existence of receptors for gp41 N-terminal region on target cell membrane is discussed.
Amino Acid Sequence↗
[Expert research on sera yielding false-positive results for HIV antibodies during screening].
The significance of different serological methods and assay systems for the verification of false positive cases of HIV infection has been analyzed on the basis of materials obtained in arbitration studies. As demonstrated by this analysis, the use of such highly specific and sensitive systems as Huma-Lab, Enzygnost, Serodia and Erythrorecombinant has made it possible to obtain a reliable result as early as at the first stage of expert diagnosis in the enzyme immunoassay and the agglutination test. The methods of radioimmunoprecipitation and indirect immunofluorescence have permitted a more precise differentiation of doubtful results than that achieved by immune blotting.
Agglutination Tests↗
[The development and use of an immunoenzyme test system for detecting and the species identification of the monkey pox virus].
An enzyme immunoassay (EIA) system for the species-specific diagnosis of monkeypox, based on the use of monoclonal antibodies (McAb) to monkeypox virus, has been developed. Immunoglobulins, isolated from McAb-containing cultural and immune ascitic fluids, have been conjugated with horse-radish peroxidase and used as detector antibodies. For immunosorption, rabbit polyclonal antibodies to the vaccine virus have been used. The specificity and sensitivity of the EIA system thus obtained have been tested on animals and humans having monkeypox and confirmed by traditional diagnostic methods (the isolation of the virus on chick embryo chorioallantoic membranes and in cell culture).
Animals↗
[Preparation of immunoenzyme conjugates of beta-lactamase from Bacillus licheniformis 749/c and horseradish peroxidase with human antibodies to HIV-1].
By using three different linkage methods with carbodiimide, glutaraldehyde and periodite, immunoenzyme conjugates of beta-lactamase from Bacillus licheniformis 749/c and horse radish peroxidase with human antibodies to HIV-1 were prepared. The human antibodies were purified by the affinity procedure on Protein-A-Sepharose 6B. The conjugates were tested in a solid phase immunoenzymatic system for the HIV-1 antigen. It was shown that the conjugates prepared by the carbodiimide linkage method had the highest titer, the beta-lactamase conjugate being superior by its titer to the respective peroxidase conjugate. In the lyophilized state the conjugates prepared with the carbodiimide linkage method were stable.
Bacillus↗
[3 cases of viral carriage detected during screening for HIV antibodies].
The results of screening more than 23,000 serum samples from persons belonging to risk groups, as well as those not belonging to such groups, in Moscow, Vilnius and Klaipeda are presented. Screening was carried out with the use of an assay system manufactured by the Scientific and Industrial Amalgamation "Antigen" (USSR). In this screening 3 HIV carriers were detected; of these, 2 were foreign students from two African countries.
Acquired Immunodeficiency Syndrome↗
Monkey pox in humans: current results.
The presented studies were performed at the WHO Collaboration Center for Smallpox in Moscow in the framework of the WHO monkey pox project. The authors recommend improved methods for rapid detection of orthopoxvirus antigen, namely passive haemagglutination (PHA) using dried stable red blood cells and ELISA in order to provide more rapid and efficient laboratory diagnosis under field conditions. Independent serologic diagnosis of monkey pox by ELISA-adsorption (ELISA-A) was proved of value for epidemiological studies and for detection of inapparent infections. The application range of the latter technique and its limitations were also determined.
Antibodies, Viral↗
Monoclonal antibodies to monkey pox virus: preparation and application.
Two fusion experiments with NSO myeloma cells yielded 30 hybrid cell lines which continuously and actively secreted monoclonal antibodies (MoAb) to monkey pox virus. Eight lines appeared to produce antibodies to specific antigenic determinants. The isotype and serologic reactivity of MoAb to monkey pox virus was characterized and the karyotype of several hybridomas determined. An enzyme labelled conjugate has been prepared from MoAb selectively reacting with monkey pox virus. This conjugate allowed the identification of monkey pox virus in the materials from patients. It also helped to determine that an orthopoxvirus isolated from wild squirrel in the Republic of Zaire was monkey pox virus.
Animals↗
Enzyme immunoassay for detection of antibodies against herpes simplex virus with the use of different viral antigens.
Enzyme-linked immunosorbent assays (ELISA) for detection of antibodies to herpes simplex virus type 1 (HSV-1) have been performed by using different immunosorbents prepared by passive adsorption of four HSV-1 antigen preparations to the wells of polystyrene microtitre plates in order to compare the the sensitivity, specificity and reproducibility of the tests. The following antigen preparations have been used: virus-infected native Vero cells and their lysates, membrane glycoproteins and virus nucleocapsid proteins. The optimal conditions have been established for each assay system: the concentrations of adsorbed antigen and the "threshold" values of the optical density. For each antigen tested except of the nucleocapsid (NC) proteins, comparable antibody titres were found in the sera of 6 patients with different forms of herpes infections and in 86 healthy subjects. In the sera of 6 herpetic patients the antibody titres were higher against NC antigen than against other antigen preparations.
Adult↗
Standardization of ELISA for detection of antibodies to orthopoxviruses.
The experience with ELISA technique utilized at serological screening for orthopoxviruses in the Republic of Ivory Coast revealed factors reducing the sensitivity and the specificity of the test. It was found out that routine controls such as "positive" and "negative" sera as well as the accepted reading of the results by two-fold or higher increase of OD values as compared to the "negative" control may be not sufficient. A significantly enhanced sensitivity and specificity of reaction was achieved by simultaneous examination of each serum under study with a control antigen. Selection of optimal dilutions of each test component followed by spectrophotometric assay and calculation of results according to the given formula contributed to the same aim. As a result of these improvements the rate of antibody detection among revaccinees was enhanced from 19 to 78.8% and the titres of ELISA and virus neutralization tests correlated in 88% of cases.
Antibodies, Viral↗
Therapeutic effect of bromvinyldeoxyuridine and several nucleotides during experimental herpetic infection.
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Animals↗
[Data from a serological survey of the population of the Republic of Congo for the presence of antibodies to orthopoxviruses. II. The species identification of the antibodies by using a solid-phase variant of immunoenzyme method].
To differentiate antibodies to monkeypox and vaccinia viruses, the solid-phase ELISA with preliminary adsorption of sera with vaccinia virus was used. The identification of antibodies in 99 serum samples obtained in the Republic of Congo from children without vaccination scars was carried out by means of this assay. No antibodies to monkeypox virus were revealed. In 62% of cases the presence of antibodies was due to vaccinia virus. In the sera of 32% of children under examination antibodies differing from those to vaccinia and monkeypox viruses were revealed. To find out the origin of these antibodies, further seroepidemiological studies are necessary.
Adolescent↗
[Data from the serological examination of the population of the Republic of Congo for the presence of antibodies to orthopoxviruses. I. A comparative evaluation of different study methods and general results].
The selective survey of the population of the Republic of Congo for the presence of antibodies to orthopoxviruses has been carried out with the use of the neutralization test, the hemagglutination inhibition (HAI) test and the ELISA. Despite a prolonged period (15 years) elapsed since the transmission of natural smallpox stopped in this country and despite the almost complete cessation of immunization against this infection since 1977, antibodies to orthopoxviruses can be detected in a considerable proportion of the population: 29%. This percentage grows as older age groups are examined, reaching 90.6% in the age groups of 16 years and over. Antibodies to orthopoxviruses have also been detected in children under 5 years of age, born after the eradication of smallpox and having no vaccination scars. The possible causes of this phenomenon are discussed. The comparison of the results obtained with the use of different tests has confirmed high sensitivity of ELISA. The HAI test is less sensitive, but this is compensated by its simplicity and its easy use for screening procedures. Besides, the positive results of this test indicate that the corresponding sera contain sufficiently high titers of virus-neutralizing antibodies detected by means of ELISA, which is of importance for their subsequent interspecific differentiation.
Adolescent↗
Monkeypox virus as a source of whitepox viruses.
Monkeypox virus cloning and isolation of the so-called 'white' clones from white pocks which this virus forms on the chorioallantoic membrane (CAM) were carried out. The isolated clones were stable and differed considerably from the parental strain. By their properties, they were identical to whitepox viruses formerly isolated from wildlife monkeys and rodents in Equatorial Africa. Besides stable 'white' clones, a number of virus cultures in the process of cloning were obtained which differed in quantitative content of virions, forming on CAM white pocks and pocks with hemorrhages. It appeared that the properties of the viral population as a whole (reaction type on rabbit skin, hemagglutination activity, etc.) depended on the rate of virions produced with different characteristics.
Animals↗
[Experimental study of cellular immunity after administration of inactivated and live virus vaccine].
Experiments were conducted on guinea pigs with the use of cell migration inhibition test of the peritoneal exudate; stimulation of a definite level of cell immunity in response to the administration of both live and of inactivated vaccine virus was shown. The results obtained are used for the interpretation of the action mechanism of the inactivated preparation in two-stage smallpox vaccination.
Animals↗
Preparation of highly purified vaccinia virus haemagglutinin.
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Hemagglutinins, Viral↗
[Neurological complications in smallpox vaccination and their prevention].
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Child, Preschool↗
[Immunological characteristics of the 2-stage method of smallpox vaccination].
As a result of observations carried out on children the authors present immunological characteristics of two-stage smallpox vaccination at different intervals (1 to 60 days) between the injection of inactivated and live vaccine. There proved to be acceleration and intensification of antibody formation after two-stage immunization in comparison with the rutine vaccination. A seven-day interval between the injection of the inactivated and live preparations was recommended on the basis of the data obtained.
Antibodies, Viral↗