Association of Myxoviruses with an Adenosine Diphosphatase/adenosine Triphosphatase/as Revealed by Chromatography on Deae-cellulose and by Density Gradient Centrifugation.

The following viruses were used in the form of pre­ parations purified from infected allantoic fluids by two cycles of alternate low (3,000 x g, 20 mins.) and high speed centrifugations (conditions are given in parenthe­ ses) : Inhibitor resistant variant of A 2 (Singapore) 57 influenza virus (48,000 x g, 40 mins.), previously puri­ fied by adsorption onto and elution from rooster red blood cells, the Blacksburg strain of Newcastle disease virus (NDV) (40,000 x g, 30 mins.), and Sendai virus (58,000 x g, 60 mins.). The sedimentable component from uninfected allantoic fluids (NC) of 12 day old chick embryos (75,000 x g, 120 mins.) was used in con­ trol experiments. The conditions of virus multiplication in chick embryos and the method of determining haemagglutination (HA) titres were those reported pre­ viously 3> 4.