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V N Bakhvalova

Publications and source records attributed to V N Bakhvalova.

15 recordsLinked to original sources
PubMed2001

Tick-borne encephalitis virus NS1 glycoprotein during acute and persistent infection of cells.

Tick-borne encephalitis virus (TBEV) was propagated in porcine embryo kidney (PS) cells until 48 h whereas human kidney (RH) cells maintained the virus persistence during at least 2 months. One of possible reasons of flavivirus chronic infection might be abnormal NS1 gene expression. Immunoblotting with monoclonal antibodies (MAbs) revealed the similarity of the intracellular and secreted NS1 nonstructural glycoprotein size and linear antigenic determinants in both the infected cell lines. However, according to the competitive binding of MAbs with the TBEV NS1 extracellular glycoprotein, its contiguous epitopes differed for acute or persistent infection. To map the TBEV NS1 glycoprotein antigenic determinants its recombinant analogues were used. All the studied MAbs could bind with the full-length NS1 recombinant protein. Deletion of the TBEV NS1 gene internal region resulted in defective NS1d1 protein without the region between 269 and 333 a.a. Lack of NS1d1 binding with 20B4 MAb and diminished binding with 22H8 and 17C3 MAbs permitted to map their antigenic determinants within or nearby deleted region, respectively. Interaction of other MAbs with the NS1 and NS1d1 recombinant proteins did not differ, suggesting that their epitopes were located in the region of N-terminal 268 a.a. or C-terminal 19 a.a. of the TBEV NS1 protein. The second NS1d2 truncated protein contained the first N-terminal 33 a.a. of the TBEV NS1 protein and was able to bind with 29G9 MAb. Taken together the data stand for the differences in the N-terminal structure of the TBEV NS1 multimers secreted from the acute and persistent infected cells whereas the intracellular and secreted monomer processing was the same. The modified NS1 protein oligomers in the RH cellular line might slow virus replication and could result in the TBEV persistence.

Animals↗
PubMed2000

Tick-borne encephalitis virus strains of Western Siberia.

Tick-borne encephalitis virus (TBEV) strains were isolated from ticks in Western Siberia for 12 years. Molecular hybridization of the 46 viral RNA with the TBEV cDNA and oligonucleotide probes revealed differences between the Siberian and Far Eastern strains. A comparison of the viral E gene fragment nucleotide sequence showed 89-98% homology between Siberian TBEV strains, whereas their similarity with strains from other populations was less than 83%. However, the viral E and NS1 glycoprotein antigenic structures appeared to be conservative because of the degenerate genetic code. This was shown by enzyme-linked immunosorbent assay with the corresponding monoclonal antibodies (MAb). The single exception was the MAb 17C3 against nonstructural glycoprotein NS1, which could distinguish Siberian from Far Eastern strains. Moreover, the neurovirulence differed between strains from the two natural populations. Lower neuroinvasiveness of the Siberian strains in comparison with Far Eastern Sofyin strain might be caused by both E and NS1 glycoprotein mutations.

Animals↗
PubMedDate not supplied

[Structural changes in the gypsy moth (Ocneria dispar L.) hemogram in polyhedrosis].

Structural changes in hemogram of Gypsy moth larvae from a population in the phase of quantity increase are studied morphometrically and cytochemically. The counts of granulocytes and prohemocytes are increased, as are the counts of hemocytes possessing phenol oxidase activity and hemocytes reducing nitroblue tetrazolium. Atypical virus morphogenesis is observed.

Animals↗
PubMedDate not supplied

[A comparison of the immune response induced by DNA or by an inactivated vaccine against tick-borne encephalitis].

BALB/c mice were immunized with recombinant plasmid DNA pSVK3-ENS1 and pcDNAI-NS3 containing, respectively, genes E-NS1 and NS3 of tick-borne encephalitis (TBE) virus. Antibodies to TBE virus proteins were detected in the blood sera of the immunized animals by the method of the enzyme immunoassay. Though the titers of virus-specific antibodies in the sera of mice immunized with protein vaccines exceeded those registered after immunization with DNA vaccines, essential protective immunity was observed after the use of both vaccines.

Animals↗
PubMedDate not supplied

[Genetic analysis of tick-borne encephalitis virus strains from West Siberia].

Tick-borne encephalitis (TBE) virus strains were isolated in West Siberia in the forest-steppe region near the Ob river in 1981-1992. Hybridization of genome RNA of 46 TBE strains with [32P]cDNA of TBE Sofyin strain revealed essential differences in the genomes of West-Siberian and Far-Eastern Sofyin strains of TBE virus. Nucleotide sequences of 6 TBE strains (1348-1503 n.) have been determined. A 89-98% homology of Siberian TBE strains has been shown, while the similarity of the respective fragment of E gene for West Siberian and Sofyin strains was no more than 81%. No significant changes in E gene of TBE strains have been detected over a 12-year period.

Base Sequence↗
PubMedDate not supplied

[Expression of the NS1 gene of tick-borne encephalitis virus in gram-negative bacteria from the mouse nasopharynx].

Bacteria were isolated from the nasopharynx of BALB/c mice and electroporated with pUR290(NS1)2 containing two copies of tick-borne encephalitis virus (TBEV) strain Sofjin NS1 under the control of the lac promoter. The plasmid persisted in transformants for at least ten passages. The NS1 gene expression was detected in Gram-negative enterobacteria via immunoblotting with monoclonal antibodies against TBEV nonstructural glycoprotein NS1. Recombinant NS1 was detected in bacterial cells and in the culture medium. Intranasal immunization with recombinant bacteria activated production of antibodies against NS1 in serum of BALB/c mice. The humoral immune response to NS1 failed to protect immunized mice from a TBEV challenge.

Animals↗
PubMedDate not supplied

[Monoclonal antibody study of antigens E and NS1 of Western Siberian tick borne encephalitis virus strains].

Antigenic structure of tick-borne encephalitis virus proteins was studied by ELISA with monoclonal antibodies (MAb) to E and NS1 glycoproteins of strain Sofyin. Envelope proteins appeared to be conservative which corresponded to previously determined nucleotide sequences of E gene fragments and deduced primary structures of the corresponding E protein. Five of six studied MAb to NS1 nonstructural glycoprotein of strain Sofyin reacted with this protein of all studied strains. The only exception was MAb 17C3 which discriminates West Siberian strains from Far Eastern strain Sofyin.

Antibodies, Monoclonal↗
PubMedDate not supplied

[Involvement of the common shrew, Sorex araneus (Insectivora, Soricidae), in circulation of the tick-borne encephalitis virus in south-western Siberia].

We presented the data on the abundance of immature instars of the taiga tick Ixodes persulcatus Schuize on the common shrews Sorex araneus L. in natural foci of tick-borne encephalitis in the south of Western Siberia. Basing on the results of virological and serological studies we demonstrated a low effectiveness of this host species as a donor of disease agent strains, which are predominant in the territory under study, for ticks feeding on shrews. The analysis of samples taken from the young shrews in winter and spring using reverse RNA transcription with polymerase chain reaction and ELISA revealed occurRence of subvirion components of the tick-borne encephalitis (RNA and capsid protein E) ether in brain, liver or spleen in 90 percent of shrews (n = 42). Neither hemagglutination antigen nor infectious virus have been detected. We discussed a possible epizootic role of the maintenance of non-infectious tick-borne encephalitis virus in overwintering animals.

Animals↗
PubMedDate not supplied

[Interrelations between Ixodes persulcatus ticks and the tick-borne encephalitis virus of the red vole (Clethrionomys rutilis) in western Siberia].

We present the data of 12-year survey (1989-2001) of the red vole population in southeastern West Siberia, including estimation of host relative numbers, abundance of immature taiga ticks, and percentage of animals with antigemagglutitnins against tick-borne encephalitis (TBE) virus. We discuss the role of demographic groups of voles as tick's hosts and their participation in the maintenance of TBE causative agent population. The estimation of spontaneous TBE infection rate in summer as well as in winter and early spring seasons, which have been made using a set of molecular-biological, serological and virological methods, demonstrates that a high proportion of red voles maintain non-pathogenic TBE causative agent over a long time, presumably, in the form of persistent infection.

Animals↗
PubMedDate not supplied

[Secretion of tick-borne encephalitis virus glycoproteins E and NS1 heterocomplex in the late stage of infection].

The heterocomplex of glycoproteins E and NS1 of tick-borne encephalitis (TBE) virus was isolated from culture fluid of continuous SPEV (porcine embryo kidney) cells by affinity chromatography on CL4B sepharose with immobilized monoclonal antibodies to TBE virus protein NS1. Comparison of the TBE E-NS1 heterocomplex from culture fluid and cells showed the predominance of secreted extracellular form. A similar TBE virus heterocomplex E-NS1 was revealed in the blood sera of patients with TBE but not in their lymphocytes. Extracellular localization of the E-NS1 complex at the late stage of infection rules out its hypothesized participation in the replication of TBE virus. Virtual absence of the heterocomplex and presence of proteins E and NS1 in high concentrations in the cells makes the nonspecific aggregation of these proteins impossible. Evidently, the extracellular heterocomplex E-NS1 may react with virusspecific antibodies or with cytotoxic T lymphocytes.

Animals↗
PubMedDate not supplied

[Isolation of a complex of tick-borne encephalitis viral proteins by affinity chromatography using monoclonal antibodies to proteins NS5 and NS3].

Affinity chromatography of lysates of continuous porcine embryo cells infected with tick-borne encephalitis (TBE) virus on sepharose with immobilized monoclonal antibodies to TBE virus proteins NS5 and NS3 results in isolation of a stable protein complex. This complex contains viral proteins NS5, NS3, p49, and, probably, two more cell proteins. This complex is not detected at the early stage of infection, and 24 h after infection its structure does not depend on the specificity of immobilized monoclonal antibodies used in affinity chromatography and on the time elapsed after the infection. Immunoprecipitates of infected cells phosphorylated TBE virus protein NS5 in vitro, but possessed no RNA-polymerase activity. Elution of the complex with buffers with pH 3.5 or 11.1 or with 2M urea failed to purify the active replicase. The complex of viral and cellular proteins isolated by affinity chromatography on different immunoadsorbents did not possess RNA-polymerase activity because of inactivation or absence of additional subunit(s).

Animals↗