[Determination of biologically active protein fractions and their polypeptide chains in pseudoplague virus (NDV)]

The protein fractions of the intact Newcastle disease virus as well as those of a disintegrated NDV (treatment with tween 80, ether and triton times 100) were separated through electrophoresis on polyacrylamid gel. Determined were the biologic activity, molecular weight and number of polypeptid chains of each fraction. It was found that 5 of the fractions obtained are composed of aggregates of 3 polypeptid chains, and 2 of the fractions represent single polypeptide chains. The haemagglutination and neuraminidase activity of the virus were found to be linked with the aggregates having molecular weight within the range of from 144,000 to 180,000 daltons. The complement-fixing activity observed is possessed by the single polypeptid having molecular weight of 62,000 daltons. It was demonstrated that the NDV strain that is not pathogenic for birds possesses a polypeptide with a molecular weight of 70,000 daltons, at is is not involved in the building of the protein aggregates.