[Modification of a method to study cell fusion induced in vitro by viruses].

A studying method of viruses induced cell-fusion is described, using monolayers of Vero monkey cells. Nature and density of cells and infection multiplicity are studied. The sensibility is equal to 4 hemagglutining units of Sendaï and accuracy about +/- 3 % of polykaryocytosis. Quantification. comparison and kinetics study of cell-fusion are allowed by this method which may lead to systematic and routine exploration of cell-fusion ability of biological extracts from slow degenerative diseases of the human central nervous system.