Cytoplasmic Particles of Chorio-allantoic Membrane and Their Relations to Purified Preparations of Influenza Virus

Ultracentrifugally sedimented preparations of Rous sarcoma virus contain antigenic groupings similar to that of the similarly sedimentable normal tissue components. 1 It would seem desirable that other newly isolated viruses be routinely examined for their content of groupings common to the tissue from which they have been derived. The demonstration of apparent physical homogeneity and unique particle size is not sufficient to warrant the assumption of alien chemical uniqueness implicit in the designation of “virus” to the isolated body. This is so because it may be expected that a stage in the synthesis of a virus would require the union of the stimulating virus particle and the protein-synthesizing mechanisms of the host. Thus the liberated particle bearing virus activity may also contain considerable portions of the host, the combination possessing new physical properties. In any case, it may be assumed that the orientation of the chemical work on these virus preparations would be affected if it became clear that a considerable portion of the isolated entity was common to a non-infected host. Virus preparations of influenza∗ were used as a model for an immunochemical assay, since so much chemical, physical, and biological data have been published on purified preparations.∗2, 3 , 4 The virus in the chorioallantoic fluid presumably is liberated into the fluid by the cytolysis of infected cells of the allantoic sac.

The chorioallantoic membranes of normal 11- to 13-day-old chick embryos were rinsed frequently in cold saline containing 0.01% merthiolate and were finely suspended in a final volume of 1 cc per membrane. The suspension was centrifuged at 4000 RPM for 1 hour and the resulting supernate at 30,000 RPM for 20 minutes. The pellets were permitted to soak at 4°C in 0.1 M borate buffer at pH 7.8 for 18 hours and emulsified.