Stepwise Degradation of Poliovirus Capsid by Alkaline Treatment

SUMMARY The kinetics of the liberation of protein components from purified poliovirus was examined under varying alkaline pH conditions at 40°. The proteins of the liberated components and of the virus capsid were analysed by sucrose gradient centrifugation and polyacrylamide gel electrophoresis. When the virus particle was treated at pH 10.0, a minor component enriched in the capsid protein VP 4 was liberated from the virus capsid and a remaining capsid structure had the same H antigenicity as intact empty capsids free of virus RNA. A second component consisting mainly of VP 2 was released from the capsid at pH 11.0 and the residual capsid contained VP 1 and VP 3. This altered capsid still possessed H antigenicity and was stable at pH 11.0, but was degraded to smaller components at pH 12.0. This smaller component did not show H antigenicity. The results suggested that the basic matrix of the particle structure is composed of VP 1 and VP 3 and it exhibits H antigenicity.