[Concentration of the Venezuelan equine encephalomyelitis virus in a 2-phase system of water-soluble polymers].

: A three-step concentration of Venezuelan equine encephalomyelitis (VEE) virus from tissue culture fluid was carried out in a two-phase system of polyethyleneglycol (PEG)--sodium dextran sulphate (SDS). The concentration method was based on the dependence of virus distribution coefficient upon NaCl content in the system which allowed alternating transfer of the virus from one phase of the system into the other. The infectious activity of the virus increased approximately 100-fold after the first step, 190-fold after the second, and 300-fold after the third step. The process of concentration was accompanied by purification of virus preparations. This was indicated by the results of immune electron microscopy which allowed visual observation of accumulation of the virus material in the preparations and decrease of the content of cell membrane elements. SDS was removed from virus preparations by precipitation with 3 M KCl solution in the cold, the procedure having no effect on the infectious activity of the preparations.