[Comparative studies of two alphavirus by macroplaque assays and by a fluorescent focus method in Vero cell lines (author's transl)].

Immune anti-Sindbis and anti-Chikungunya ascitic fluids have been titrated by the classic way of plaque reduction and by a quick fluorescent focus method using an indirect staining. The results are comparable, allowing to consider the use of this quick and inexpensive technic for counting-assays by neutralization.