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Biomedical subjects

Iu S Boriskin

Publications and source records attributed to Iu S Boriskin.

At least 19 recordsLinked to original sources
PubMedDate not supplied

[Effect of the synchronization of cell culture chronically infected with tick-borne encephalitis virus on the synthesis of virus antigen].

A cell culture chronically infected with tick-borne encephalitis virus was synchronized by the methods of double thymidine block and mitotic selection. There was a correlation between the time at which the cells entered the S period of the cell cycle and 4-8 fold increase in the number of cells carrying the virus antigen detectable by immunofluorescence.

Antigens, Viral↗
PubMedDate not supplied

[Effect of host cells on the course of chronic rabies virus infection in cell cultures].

Different patterns of rabies virus infection were observed in BHK-21/13S and HEp-2 cell cultures at late stages of persistent infections. The infection of BHK-21/13S cells was characterized by periodical increases and declines in the portion of the antigen-containing cells (from 100% to less than 1%) and low infectivity titers which did not correspond to fluctuations in the antigen production and occasional resistance to challenge with vesicular stomatitis virus. In contrast, persistently infected HEp-2 cell culture exhibited a more constant course of antigen production which never reached extreme points; the infectivity titers generally correlated with the portion of the antigen-containing cells. Cultivation in the presence of antirabies serum did not "cure" either of the cultures.

Antigens, Viral↗
PubMedDate not supplied

[RNA analysis of the measles virus in a human cell culture of the chronic infection].

Synthesis of virus-specific RNAs in human HEP-2 and L-41 cells chronically infected with measles virus was studied in comparison with synthesis of viral RNA in acutely infected L-41 cells. The RNA, a component of RNP isolated from chronically infected cells, was shown to be represented mainly by "minus" chains and to contain 23-25% "plus"-RNA. It was demonstrated by blotting hybridization that 1 species of genomic RNA with a molecular weight of 5 megadaltons was synthesized in acute infection whereas in chronically infected cells a small amount of subgenomic RNAs was additionally detected in RNP. The level of virus genome transcription in chronically infected cells was 7-8 fold lower than that in acute infection. The RNA-transcriptase activity of RNP isolated from chronically infected HEP-2 and L-41 cells was also lower than RNP activity from acutely infected L-41 cells. The observed features of virus-specific RNA synthesis in chronically infected cells seem to be likely to play a role in the maintenance of virus persistence.

Cell Line↗
PubMedDate not supplied

[Effect of elevated temperature on the persistence of measles virus vaccinal strain L-16 in a human cell culture].

The influence of high temperature (40 degrees C) on the virus carrier state and synthesis of virus-specific macromolecules in the HEp-2 cells--measles virus system was studied. The fluorescent antibody technique showed that cultivation at this high temperature led to changes in virus antigen morphology, a decrease in the number and then complete disappearance of the cells producing virus-specific antigen. Simultaneously, gradual cessation of synthesis of all kinds of virus-specific RNA was observed in chronically infected cells. The method of radioimmunoprecipitation showed the incubation at 40 degrees C to affect first of all the synthesis of virus nucleocapsid protein. The temperature-sensitive nature of synthesis of virus macromolecules may be explained by the existence of its mutations in the genome of the persisting virus.

Antigens, Viral↗
PubMedDate not supplied

[Epitope analysis of mumps virus proteins in a persistent cell culture infection: changes in the hemagglutinin-neuraminidase polypeptide].

Monoclonal antibodies (MABs) against major structural mumps virus proteins were used for epitope analysis in primarily and persistently infected HEp-2 cells by means of immunofluorescence and radioimmunoprecipitation techniques. Qualitatively, no differences were found in MAB binding between corresponding proteins of the original and persistent viruses, whereas quantitative differences observed might be explained in terms of weakened viral protein synthesis in persistent infection. Limited proteolysis of MAB-bound antigen has revealed alterations in certain epitopes on persistent virus HN polypeptide. Despite the inability of HEp-2 infected cells for hemadsorption, HN protein was expressed on the surface of these cells to the same extent as in the hemadsorbing system of mumps virus-infected Vero cells.

Animals↗
PubMedDate not supplied

[Analysis of the possible mechanisms for the persistence of the vaccinal strain of the measles virus in a human cell culture].

The mechanisms (factors) of the measles virus vaccine L-16 strain persistence in HEp-2 cell culture were analysed. Among the known mechanisms, most likely is the reduction of the cell-destroying properties of the persisting virus due to mutations in nucleoprotein gene manifested by changes of the isoelectric point of NP protein and temperature sensitivity of its synthesis.

Cells, Cultured↗
PubMedDate not supplied

[Effect of magnesium sulfate on the reproduction of the measles virus in cell culture].

Magnesium sulphate in concentrations of 25-50 mM induced reproducible increase in titers of extracellular measles virus (by 0.5-2.0 1g TCD50/0.5 ml) in Japanese quail embryo cells. MgSO4 effect was observed with all methods of cell cultivation: stationary, roller, or on microcarriers. Its effect was associated not with its stabilizing influence on the extracellular virus but rather with the stimulation of the synthesis of intracellular viral proteins.

Animals↗
PubMedDate not supplied

[Arenavirus antigen persistence in continuous cell lines. Attempts at isolating the infectious virus].

An attempt was made to isolate an infectious virus from FL cells in which arenavirus antigen revealed by immunofluorescence tests persisted. Inhibitors of macromolecular synthesis, ultraviolet irradiation, fusion with BHK 21/13S cells, and transfection of BHK-21/13S cells with DNA from FL cells were tested in order to activate the virus. Negative results were obtained in each of these experiments. Prolonged cultivation of FL cells at 31 degres or 41 degrees C resulted in a two-fold increase in proportion of the antigen-containing cells or its complete elimination, respectively. The likelihood of integration of transcribed proviral fragment into the cell genome is discussed.

Animals↗
PubMedDate not supplied

[Chronic cell culture infection with the rabies virus].

Three cell cultures chronically infected with fixed rabies virus, strain MNIIVP-74, have been obtained: HEp-2/2, BHK/13S, and RK-13. In the former two cultures, the infectious virus titers were 2.0 to 5.25 Ig LD50/ml. In RK-13 cells, traces of the infectious virus were found. In the chronically infected HEp-2/2 culture the maximum amount of the antigen-containing cells determined by the fluorescent antibody procedure was 60% and in BHK/13S 80%. Chronically infected cultures had a reduced growth rate and were as sensitive as the controls of superinfection with vesicular stomatitis virus. The virus recovered from chronically infected culture produced a disease in mice at later intervals than the original virus used in the same doses.

Animals↗
PubMedDate not supplied

[Cytologic and histochemical study of cell cultures chronically infected with fixed rabies virus].

Cytoplasmic inclusion bodies corresponding in their tinctorial properties to Negri bodies were detected in TEp-2/2 and BHK-21/13S cell cultures chronically infected with fixed rabies virus. The number of cells containing the inclusions was always than that of the cells producing virus-specific antigen. Histological examinations of chronically infected cultures revealed considerable inhibition of the acid phosphatase activity, some weakening of the reaction to alkaline phosphatase, and a marked decline in the activity of succinate dehydrogenase. The intensity of reaction to RNA in chronically infected cultures was increased, particularly in those zones of the cells where RNA-containing inclusions were detected. The activity of the respiratory enzyme HAD-H2 tetrasolium reductase in HEp-2/2 cells was reduced and in BHK-21/13S cells increased as compared to the control.

Acid Phosphatase↗
PubMedDate not supplied

[Synthesis of measles virus proteins in chronically infected human cell cultures].

Synthesis of measles virus proteins in primary and chronic infection of L-41 and HEP-2 cells was studied by radioimmunoprecipitation test and polyacrylamide gel electrophoresis. Synthesis of measles virus main structural proteins, H, P, NP, and M, was found to occur in chronically infected cells. Persistence of measles virus in the systems under study was shown not to be accompanied by changes in electrophoretic mobility of virus polypeptides as compared with proteins synthesized in primary infection. NP protein of the original virus, however, differed significantly from NP protein of the persisting virus in its charge which indicated aminoacid replacements apparently due to mutations of the appropriate region of the virus genome. The mechanism of measles virus persistence in these systems was shown not to be associated with disorders in matrix protein synthesis. Use of monoclonal antibodies in fluorescent antibody technique and radioimmunoprecipitation revealed the stability of a number of antigenic determinants in persisting measles virus in L-41 and HEP-2 cell cultures.

Chronic Disease↗
PubMedDate not supplied

[Effect of a poly I-poly C complex with poly-L-lysine on experimental tick-borne encephalitis].

The influence of the poly(I)-poly(C) complex with poly-l-lysine on the development and course of experimental tick-borne encephalitis was studied in Macaca rhesus monkeys. Prophylactic administration of the substance under study, although not preventing the disease, modified its course and facilitated recovery of the animals. Poly(I)-poly(C) and its complex with poly-l-lysine were shown to have no effect on production of infectious virus or its antigen demonstrable by the immunofluorescence procedure in HEp-2 cells chronically infected with tick-borne encephalitis virus.

Animals↗
PubMedDate not supplied

[Virus-specific RNA synthesis in a cell culture in acute and chronic infection with the tick-borne encephalitis virus].

Virus particles produced in acute and chronic infection of cell cultures with tick-borne encephalitis virus (TBE) and examined by centrifugation in sucrose density gradient had the buoyant density of 1.19 g/ml and sedimentation constant 290 S. Studies of the synthesis of virus-specific RNAs in the cytoplasm of TBE virus chronically infected cells revealed synthesis of all RNA classes typical of TBE virus reproduction in acutely infected cells. The difference was in the high percentage of polyadenylation of intracellular virion RNA in chronic infection (30%) as compared with polyadenylation of virion RNA in acute infection (8%). This fact may be one of the causes of a low infectious virus yield in chronically infected cultures where the level of virus-specific antigen synthesis is high.

Cells, Cultured↗