[Detection and antigenic characteristics of the recombinant nucleocapsid proteins of Lassa and Marburg viruses].

Two plasmid vectors, which allow the recombinant polypeptides of Lassa and Marburg viruses to be expressed in prokaryotic cells E. coli strain BL21 (DE3), were produced. The two recombinant polypeptides are able to bind specific antibodies.

[Conformational changes in Lassa viral proteins when exposed to antibodies and complement].

Addition of the complement to the antigen in Lassa virus ELISA stimulated the sensitivity and specificity of the assay. The effect depended on the mouse Ig subclasses. ELISA plate sensitization with IgG2a and IgG2b increased the sensitivity of ELISA 8-16 times.

[Isolation and characteristics of low molecular weight recombinant peptides, representing antigenic domains in the NP protein of lymphocytic choriomeningitis virus].

High- and low-molecular recombinant peptides of LCM virus nucleoprotein, representing individual immunodominant antigenic sites, were obtained in pJC40 expressing vector and studied in solid-phase enzyme immunoassay. 2-7% proteins resultant from total cellular synthesis are recombinant peptides. Comparative analysis of antigenic properties of recombinant peptides and native viral protein showed that recombinant peptides are virtually not inferior to native viral protein in antigenic properties.

Lassa and Mopeia virus replication in human monocytes/macrophages and in endothelial cells: different effects on IL-8 and TNF-alpha gene expression.

Cells of the mononuclear and endothelial lineages are targets for viruses which cause hemorrhagic fevers (HF) such as the filoviruses Marburg and Ebola, and the arenaviruses Lassa and Junin. A recent model of Marburg HF pathogenesis proposes that virus directly causes endothelial cell damage and macrophage release of TNF-alpha which increases the permeability of endothelial monolayers [Feldmann et al. , 1996].

[False-positive reactions in laboratory diagnosis of Lassa, Marburg, and Ebola viral hemorrhagic fevers and AIDS].

Sera of normal subjects and AIDS patients living in Minsk and Odessa were tested for antibodies to hazardous viral infections Lassa, Marburg, and Ebola. Four to 16% of examinees were seropositive to Ebola virus, 0.8 to 2.

[The dynamics of the formation of IgG subclasses in Balb/c and CBA mice infected with the LCM, Lassa and Mopeia viruses and their role in diagnosis].

The dynamics of the induction of individual IgG subclasses in BALB/c and CBA mice and their role on the diagnostics of arenaviruses LCM, Lassa and Mopeia was studied. The study demonstrated that in solid-phase enzyme immunoassay (EIA) isotypes IgG2a and IgG2b to virus Mopeia could be used for the differentiation of virus Mopeia from viruses LCM and Lassa, and the antigen of virus Mopeia could be used for the preparation of diagnostic EIA systems not only to nonpathogenic virus Mopeia, but also to pathogenic viruses LCM and Lassa.

[Serological evidence of Lassa virus circulation in the Republic of Guinea].

Seroepidemiological investigations in Guinea were carried out to estimate the areas of Lassa virus circulation. The recombinant protein of Lassa virus nucleocapsid was used as the antigen to analyse blood sera by ELISA. In some regions, from 30 to 54.

[The localization and preliminary characteristics of antigenic sites (B epitopes) in the nucleocapsid protein of the Lassa virus].

Nucleocapsid protein of Lassa virus contains 4 epitope sites. Three of them were localized in amino acid position 123-1 27, 337-346, and 518-527. Monoclonal antibody 1108 specific to Lassa virus NP-protein reacted with 123-127 synthetic peptide in solid-phase ELISA and precipitated nucleocapsid proteins of Machupo, Tacaribe, and Mopeia arenaviruses in RIP.

[The immunogenic activity of the Lassa virus structural proteins].

The immunogenic properties of Lassa virus GP1, GP2, and NP polypeptides were studied in rabbits. Lassa virus NP polypeptide, in contrast to GP1 and GP2 polypeptides, was shown to induce the highest titres of antibodies determined by IFA and ELISA tests. Moreover, the antibody relative avidity experiment showed that the anti-NP antibodies has ELISA index of 0.

[Monoclonal antibodies to the Machupo virus: their isolation and preliminary characteristics].

Six monoclonal antibody-producing hybridoma cell lines were generated by fusion of NS-1 myeloma cells with BALB/c immune splenocytes. Monoclonal antibodies (MCA) specific to Machupo virus NP protein were used to study cross-reactivity between pathogenic and nonpathogenic arenaviruses. It was shown that 3140 MCA cross-reacted in IFA with Lassa, Tacaribe, and Tamiami arenaviruses whereas 3101 MCA reacted with Machupo virus alone.

[The detection of the Marburg virus antigen by solid-phase immunoenzyme analysis].

Comparative studies of two variants of the enzyme-linked immunosorbent assay (ELISA) were carried out to determine the sensitivity of the detection of Marburg virus antigens in Vero cells. Both competitive and two-antibody ELISA variants detected as little as 5 ng of Marburg virus antigen. The Vero cell monolayer was found to produce 5-50 ng/0.

[The production of antibody-producing hybridomas to the Lassa virus].

The work deals with obtaining hybrid cell lines producing monoclonal antibodies to Lassa arenavirus. To obtain preparations for the screening of hybridomas by indirect immunofluorescence techniques, the dynamics of the accumulation of Lassa virus antigen in cell cultures Vero and 4647 was studied. The maximum accumulation of the virus antigen in Vero cells was shown to occur on day 3 after inoculation with a dose of 1.

[Recombinant monoclonal antibodies to the Lassa virus: the formation of reactive paratopes].

Eighteen hybrid lines secreting recombinant monoclonal antibodies to Lassa virus were produced by fusion of mouse splenocytes with antibody-secreting X-63 myeloma cells. Interrelations between the structure and reactivity of the antibodies were studied by different serological and immunochemical methods. Monoclonal antibodies were divided into different groups according to their serological properties and macromolecular structure.

[The isolation and characteristics of recombinant monoclonal antibodies to the Lassa virus].

Recombinant monoclonal antibodies to Lassa virus were produced. The reactivity of the monoclonal antibodies was studied by indirect fluorescence antibody (IFA) technique, enzyme-linked immunosorbent assay (ELISA), and radioimmunoprecipitation method. The observed reactivity did not correlate with IgG isotyping groups.

[Virus-specific proteins and RNA of the virus of hemorrhagic fever with renal syndrome].

Virus-specific proteins G1, G2, and N with molecular weights of 70, 55-57, and 50 kilodaltons, respectively, were detected by radioimmunodiffusion tests in VERO E-6 cells infected with strains of virus of hemorrhagic fever with renal syndrome (HFRS) isolated in the European USSR from a patient with HFRS, a fatal human case of HFRS (the strains K-27 and P-360) and from a bank vole (strain CG-1820). The sera from human convalescents after HFRS in the European USSR and rat sera prepared with the CG-1820 strain precipitated proteins possessing similar electrophoretic characteristics from a lysate of cells infected with the CG-1820, K-27 and P-360 strains. The sera from human HFRS convalescents in the Far East did not precipitate protein Gl.

Lassa virus glycoproteins: antigenic and immunogenic properties of synthetic peptides to GP1.

Synthetic peptides corresponding to predicted Lassa virus GP1 glycoprotein B-epitopes were used to study the antigenicity and immunogenicity of the protein. ELISA results showed that guinea pig polyclonal anti-Lassa virus serum bound effectively to peptides corresponding to amino acid residues 119-133 and 164-176 of the GP1 protein. Essentially it did not react to a peptide corresponding to GP1 amino acid residues 234-256.

[Characteristics of monoclonal antibodies against Lassa virus].

Some properties of monoclonal antibodies to the Lassa virus have been characterized. The competitive immunoenzyme analysis has revealed the presence of at least three antigens in the Lassa virus nucleoprotein.

[Production of infectious virus and the accumulation in Vero cells of Pichinde virus antigens detectable by an indirect fluorescent antibody method].

The dynamics of accumulation of infectious Pichinde virus in the culture medium and virus-specific antigens in cells was studied in relation to multiplicity of infection in a multicycle experiment. Differences in the fluorescence pattern of Pichinde virus antigens in IFAT were found to depend on the use of acetone or formaldehyde for fixation of the infected cells.

[Experimental evaluation of the pathogenicity of Lassa virus variants].

Pathogenicity for guinea pigs and white mice of various Lassa virus variants: native, having had 1 passage in Vero cell culture and 4 passages in newborn white mouse brain; a virus having gone through 10 passages in Vero cells and 8 mouse brain passages (variant No. 10); a small-plaque clone derived from variant No. 10 by the method of plaque-to-plaque cloning (variant No.

[Inhibition of the accumulation of the Lassa virus in Vero cells by immune gamma globulin and complement].

Specific inhibition of Lassa virus replication in Vero cells was found to be better achieved with immune gamma globulin in combination with complement than with gamma globulin alone. According to the authors, the inhibitory effect of these preparations is due to the cyto-destructive action of antibodies and complement on the infected cells.