EN
The technique widely applied since longest in concentration and purification of animal viruses, consists in precipitation of viruses from suspensions of the cells broken, by means of ammonium sulphate and its elution by means of neutral or alkaline buffers (Brown and Kolmer, 1937). Among other techniques, which appeared to be suitable to such or other degree, the techniques of precipitation by means of heavy metals, of ion-exchange filtration, ultrafiltration, pre-evaporation, electrophoresis and ultracentrifugation deserve mentioning. Among the above techniques it is the ultracentrifugation technique, which is most frequently applied at present. All the above virus purification methods are single-stage ones. For obtaining preparations purified and condensed to a higher degree, many-stage methods using several techniques ought to be applied. The aim of the investigations presented in this paper is to estimate the value of two single-stage purification methods (using ammonium sulphate and centrifugation) of some viruses pathogenic for cattle, as an initial trial for further investigations on determining optimal many-stage methods.