Purification, characterization, and quantitation of the antigen employed in the immunodiffusion test for diagnosis of equine infectious anemia.

This research article describes a method for extracting and purifying equine infectious anemia (EIA) antigen from infected horse spleens. It further develops a system for measuring the antigen content in related preparations.

Extraction and Purification Process

• Researchers utilized the spleen of horses that were infected with the EIA virus.
• This infected material was subjected to a pH treatment, which likely adjusted the acidity of the sample to better isolate the EIA antigen.
• After pH treatment, (NH4)2SO4 fractionation was performed to further isolate the sample.
• The EIA antigen was additionally purified by means of affinity chromatography, which separates substances based on their binding affinities.

Confirmation of Antigen Homogeneity

• The homogeneity of the antigen, that is, its uniformity and consistency, was confirmed using sedimentation rate and sedimentation equilibrium experiments.
• These experiments established that the antigen had a sedimentation coefficient (S20, w) of 0.51.
• A molecular weight of 7600 was calculated from the sedimentation equilibrium analysis.

The Nature of the EIA Antigen

• The amino acid composition of the purified antigen was analysed.
• This analysis indicated that the EIA antigen is an acidic protein.

Quantitation of Antigen Content

• Researchers developed a method to quantify the amount of antigen present in antigen-containing preparations.
• This method used radical immunodiffusion (RID) and the pure antigen extracted in the earlier steps of the research.