[The isolation and results of the study of the protein structure of spirochetes isolated from I. ricinus ticks in Byelarus]. / Izoliatsiia i rezul'taty izucheniia belkovoi struktury spirokhet, vydelennykh v Belorussii ot kleshchei I. ricinus.

Four hundred and eighty Ixodes ricinus (278 female and 202 male) samples collected in the natural biotopes of 13 administrative districts in southwest Byelarus were studied via DSK-H medium (Sigma) inoculation. Twenty-four spirochetes isolates (3, 2, 1, and 18 in the Brest, Gomel, Mogilev, and Grodno regions, respectively) were obtained on the territory of Byelarus. After adapted to the medium, most isolates (as many as 7 x 10(6)-5 x 10(7) microbial cells per ml) in the stationary phase. All the obtained isolates were cryoconserved at the level of 2-6 passages and after -70 degrees C storage during 4-6 months (a followup period) they were able to recover their initial reproductive activity in the fresh BSK-H medium. Proceeding from preidentification using a comparative electrophoretic analysis of the molecular mass of polypeptides, the pattern of their specific reactivity with polyclonal serum antibodies from the rabbit immunized with cultured Borrelia afzelii (Ip21 strain), in immunoblotting and indirect immunofluorescence assay, I. ricinus spirochetes were referred to Borrelia burgdorferi sensu lato isolates.

[The cultivation and physicochemical properties of the Josiah strain of the Lassa virus]. / Kul'tivirovanie i fiziko-khimicheskie svoistva virusa Lassa shtamm Dzhoziia.

Data on the stability of Lassa virus, Josia strain, isolated from man to the effect of physicochemical factors (heating at 50 degrees C, solutions of urea and formalin of various concentrations, UV irradiation) as well as on the time course of this strain reproduction in cell lines of different origins are presented. Recommendations for lowering of reactogenicity of the virus-containing material are given. The experimental results must be taken into consideration in the development and manufacture of diagnostic and therapeutic-prophylactic preparations for Lassa fever.

[Chronic infection of BHK-21 cells by the Machupo virus. The development of the system and properties of the virus produced by cells of this line]. / Khronicheskaia infektsiia kletok BHK-21 virusom Machupo. Stanovlenie sistemy i nekotorye svoistva virusa, produtsiruemogo kletkmai étoi linii.

A new model of chronic infection of BHK-21 cells with Machupo virus has been obtained. The chronically infected culture of BHK-21-M cells differed morphologically from the control culture by the presence of giant mono- and multinuclear forms with granular cytoplasm and by an increase in the number of small rounded cells. In the system of BHK-21-M cells, the persisting virus was produced permanently but the per cent of infected cells determined by indirect immunofluorescence and the infectious centre method was not high (12-17%). The main factor contributing to the development of Machupo virus persistence in this cell system appears to consist in the formation of defective interfering particles.

[Effect of the diapause in the Ixodes ricinus (Ixodidae) tick on the multiplication of the tick-borne encephalitis virus in its body]. / Vliianie diapauzy kleshcha Ixodes ricinus (Ixodidae) na razmnozhenie v ego organizme virusa kleshchevogo éntsefalita.

The tick encephalitis virus was found to multiply more intensively in ticks developing without diapause. Thus, in larvae developing with diapause, in 4 and 8 weeks after they feed on infected animals, the virus titers were 3.0 and 3.5 lg LD50 respectively. At the development without diapause the titers were 4.3 and 5.3, respectively (P less than 0.05). The virus titers in infected nymphs developing without diapause were 2.5 to 3.9 lg LD50 higher than those of the diapausing individuals. In diapausing larvae and nymphs the tick encephalitis virus remained for a long time (8 to 10 weeks) without fall of titers. The fall of virus titers was not recorded either during the moulting of larvae for nymphs and nymphs for imago but in hungry ticks, which were maintained for a long time at 18 to 23 C, the amount of virus gradually diminished.