The separation of disease-related components associated with equine infectious anemia (EIA) : a dissertation

Abstract

By applying the technique of gel filtration to horse leukocyte cell culture fluid containing infectious material of equine infectious anemia (EIA), three major fractions were obtained. The first fraction, Fraction I, which was eluted in the void volume, contained spherical "virus-like" particles 28 to 36 mμ in size. Ether treatment of concentrated preparations of this fraction resulted in the apparent disruption of these particles and formation of long strands of material as revealed by electron micrography. Contrast enhancement staining of the particles with one per cent phosphotungstate pH 6.8 revealed the presence of 9 to 12 projections on the surface of the particles. Fraction I was antigenic in sheep but did not react with the diagnostic precipitin reagent. Conglutinating complement antibody to Fraction I was not detected in any of the horses examined. Fraction I did not cause hemagglutination of washed chicken erythrocytes. The second major fraction of the cell culture fluid, Fraction II, reacted with the diagnostic precipitin reagent and caused hemagglutination of washed chicken erythrocytes. The serological activity of Fraction II appeared to be unstable. Sheep injected with this material frequently developed anaphylactic shock after the second injection. Materials bearing an antigenic identity to Fraction II were isolated by gel filtration from serum and urine of infected horses. The retention characteristic and the capacity to pass the glomerular barrier suggest that Fraction II is a small molecular weight component. The presence of antibodies to Fraction II in infected horses, and the apparent absence of antibodies in non-infected horses suggests that this fraction component plays a role in EIA. The possibility that serologically active components, such as Fraction II, are capable of being removed from the circulating system may explain why serologic tests for EIA yield inconsistent results. The third fraction eluted after considerable washing, was non-antigenic and not active serologically. Fraction III was believed to consist of small molecular weight metabolic constituents of cell culture fluid.