[The penetration of the Marburg virus into eukaryotic cells]. / Proniknovenie virusa Marburg v éukarioticheskie kletki.

The early stages of infection of Vero-E6 cell culture with Marburg virus, a member of filovirus family, highly pathogenic for man, were studied. Virus multiplication was completely or significantly inhibited by lysosomotropic agents (LTA) of two types: weak base (ammonium chloride) and ionophore monensin. The level of the inhibiting effect was proportional to LTA concentration and was maximal when the drug was introduced into the culture medium before virus inoculation. Complete inhibition of Marburg virus replication in Vero-E6 cells in the presence of 20 (30) mM ammonium chloride ("lysosomotropic blocking") was overcome by a short-time treatment of the cell culture with the virus adsorbed on it using a medium with a weak-acid pH (4.0-5.0). The results are discussed from the point of view of the mode of this virus penetration into eukaryotic cells.

[pH-dependent fusion of eukaryotic cells, caused by arenaviruses, pathogenic and non-pathogenic for humans]. / pH-zavisimoe sliianie éukarioticheskikh kletok, vyzyvaemoe patogennymii nepatogennymi dlia cheloveka arenavirusami.

The conditions necessary for fusion from inside (FFWI) of the BHK-21 cell culture affected by the Lassa and Mopeya arenaviruses were studied. The fusion was shown to occur only in the slightly acid medium and at lower pH meanings for the Mopeya virus, than for the Lassa virus.

[The Mopeia virus induces pH-dependent "fusion from within" in a BHK-21 cell culture]. / Virus Mopeiia indutsiruet pH-zavisimoe "sliianie iznutri" kul'tury kletok BHK-21.

The capacity of BHK-21 cell culture to produce Mopeia virus (Arenaviridae family) to form syncytium upon acidification of the culture medium to pH 5.5 and lower was demonstrated. The cell fusion requires their active virus production: a virus titre in the culture medium must be at least 10(5) PEU/ml. The inhibition of virus multiplication with ammonium chloride as well as treatment of the cells before the medium acidification with immune serum reduced syncytium formation markedly. No cell fusion was observed upon acidification of the medium immediately after virus adsorption to cells. Thus, the observed cell fusion under the influence of the virus is an "internal fusion" and confirms our previous data on the endocytosis mode of arenavirus penetration into the cell.