FURTHER STUDIES ON THE PURIFICATION OF POLIOMYELITIS VIRUS'

Some years ago (1930), we presented evidence from several series of experiments that the virus of poliomyelitis is found largely in the water-soluble globulins of brain-cord suspensions and filtrates. This demonstration was based both on a separation by primary dialysis against distilled water, with subsequent re-moval of the precipitate, and on salting out with ammonium sulphate and subsequent dialysis of the precipitate. These experiments were carried out, however, with the ordinary crude saline extracts or suspensions of brain and cord from poliomyelitis monkeys, and the separation may have been due chiefly to the adsorption of the virus on the contaminating proteins and lipins, rather than to the nature of the relatively small amount of the virus itself. With the demonstration by several investigators including Howitt (1930), Clifton, Schultz and Gebhardt (1931), and Schaeffer and Brebner (1933) that lipoids and some proteinaceous material can be removed from saline virus extracts by adding equal volumes of ether, with little resulting damage to the virus, an opportunity was presented to determine whether the earlier observations would hold true for this somewhat purified virus, and whether further concentration might be accomplished. A number of experiments with such virus extracts have been carried out, subjecting them also to a series of precipitations, dialyses and centrifugations, resulting in a more potent product, and demonstrating that the virus is present both in the euglobuli