Immune complexes in Aleutian disease: demonstration of antibody on isolated virus

The specific binding of Staphylococcal protein A for mammalian immunoglobulin G was used to demonstrate IgG associated with Aleutian disease virus (ADV) when isolated from infected mink tissues. Protein A specifically bound to mink serum Ig with no reaction with other serum or tissue proteins. Protein A labeled with 131Iodine reacted with crude virus preparations but not with virus that had been purified by freon extraction to the point where it became reactive with antibody by counterimmunoelectrophoresis. Binding to purified ADV was restored when the purified virus was first reacted with antibody. Results of urea treatment indicated this as an alternative method for isolation of ADV free from antibody.