Abstract
The isolation and purification of particulate components biologically characteristic of influenza virus A (PR8 strain) (l), influenza virus B (Lee strain) (2), and the swine influenza virus (3) have been reported. These components were obtained, by adsorption on and elution from chicken red blood cells combined with ultracentrifugation or by ultracentrifugation alone, from chorioallantoic fluid of chicken embryos infected with the respective types of the influenza virus. By these procedures concentrates of the particles were obtained in preparations of a high degree of homogeneity with respect to particle kind, with characteristic sedimentation constants and average particle sizes, as determined from sedimentation data and from electron micrographs. Preliminary chemical analyses, already reported briefly, showed the three types of influenza virus to be constituted of lipoprotein-carbohydrate complexes containing nucleic acid of the desoxypentose type. The present paper is concerned with a detailed description and comparison of the analyses made on influenza viruses A (PR8 strain) and B (Lee strain) and the swine influenza virus.
Highlights
The strains of the influenza viruses employed for analysis were the same as those already described in the reports on the studies on purification (l-3)
On all of the samples chosen for study, examinations were made with the analytical ultracentrifuge, the Lamm scale method being used, and with the electron microscope
The results indicated a high degree of homogeneity of the preparations with respect to particle kind. These data obtained on ultracentrifugation and with the electron microscope will be described in detail in a subsequent publication
Summary
In the previous work with the three types of virus, various modifications in methods and technique were introduced or discarded from time to time. The step of preliminary dialysis against Ringer-calcium chloride solution (l), frequently used in the earlier work to remove amorphous urates and inorganic salts, was omitted This procedure was impractical with large volumes of chorioallantoic fluid, and its principal advantage, the apparent dispersing action and prevention of marked aggregation of the virus particles when they were sedimented at 27,000 g, was supplanted by the reduction of the centrifugal field to 20,000 g for final sedimentation. Solutions of the swine influenza virus have consistently appeared to be clearer and have exhibited a brighter opalescencethan those of the two human types in comparable concentrations. The alcohol-ether-insoluble fraction was dried to constant weight on the crucible for analysis, as described in a subsequent section. Alcohol-ether-soluble fraction was transferred to a tared weighing bottle, evaporated, and the dry weight determined. Aliquots, according to the method of Kirk, Page, and Van Slyke [7]
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