Lansing poliomyelitis virus in gently clarified homogenates is not measurably inactivated upon exposure to pH values 1.5 or 10.5 at 4 C for at least 24 hours. At pH values 3.6, 4.7, 7.1, and 8.4 this resistance is maintained over the entire 21-day period of observation.

A study of the extraction of the virus from crude homogenates revealed that partial liberation of the virus can be effected at pH 2.0, ionic strength 0.1, but not at ionic strength 1.0 or 5.0. At pH 7.0 the virus is readily extracted at ionic strength 1.0, but is not extracted at ionic strengths 0.01, 0.1, and 5.0. At pH 9.0 the virus is completely liberated at ionic strengths 0.1 and 1.0, but is insoluble at ionic strength 5.0. The degree of extraction effected was paralleled by a correspondingly high or low degree of virus purification. The highest relative infectivity of any of the fractions was 2.5.

The use of n-butanol under specified conditions of ionic strength and hydrogen ion concentration was effective in removing most of the lipid and non-virus protein from homogenates of Lansing-infected cotton rat CNS tissue. Relative infectivities up to forty were obtained without loss of virus.

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