PURIFICATION AND ANALYSIS OF INFECTIOUS VIRIONS AND NATIVE NONSTRUCTURAL ANTIGENS FROM CELLS INFECTED WITH TICK-BORNE ENCEPHALITIS-VIRUS

By employing the techniques of column chromatography and membrane filtration, we have succeeded in purifying flavivirus particles with low particle to infectivity ratios and free from contamination with cellular proteins. Virus particles purified by this method have an average diameter of 53 nm, a particle to infectivity ratio of less than 10, and a Kp (partition coefficient) consistent with a molecular weight of 2.63 · 107. In addition it has been possible to purify the extracellular form of non-structural protein 1 (NS1), which in its native form appears to be a hexamer. It is also apparent from these studies that the slowly sedimenting haemagglutinin particle (or SHA) is an artifact of purification methods using gradient centrifugation. This technology should not only prove useful in the laboratory for studying the detailed structure of these viruses and the proteins encoded by them, but should also prove useful in industrial vaccine manufacture where large volumes of highly pathogenic material are handled. © 1990.