A complement fixing antigen in the livers of birds infected with an avian leukovirus (erythroblastosis virus).

Extracts of erythroblastosis affected livers from which much of the structural protein had been removed were prepared by acid denaturation. These extracts contained complement fixing "soluble" antigen in a form which was not associated with viral or subviral particles. Ultracentrifugation can be of assistance in separating complement fixation activity from contaminating material in these extracts

The removal of "nucleic acid" from an antigen present in the livers of chickens with erythroblastosis.

The recovery of viral antigen in a pure form from tissue can be hindered by the small amount of antigen present relative to the remaining normal tissue constituents with which the antigen may form loose associations. An antigen from the livers of chickens with erythroblastosis had earlier seemed to be associated with nucleic acid. The present work suggests that this material, which reacts with reagents for DNA and RNA but is soluble in 0.2N HClO4, is only a contaminant and not an integral part required for complete activity of the antigen. Treatment with 0.2N HClO4, together with precipitation of the active protein by 60% saturation of aqueous solutions with ammonium sulphate, removes the nucleic acid without destroying antigenicity. The procedure results in a marked degree of purification of the antigen (732-fold with respect to original liver protein) but contaminants still remain. A contaminant absorbing at 260 nm resisting extraction with 0.2N HClO4, can be partly eliminated if the solution is treated with ether-alcohol to remove lipid

A "liver" antigen associated with avian erythroblastosis: binding by bentonite and precipitation with sodium dodecyl sulphate.

The properties of a complement fixing antigen, EbAg, extracted from erythroblastosis-affected chicken livers are described. The antigen in extracts freed of structural protein is strongly bound by bentonite, but not by barium sulphate. Strongly alkaline solutions of sodium dodecyl sulphate are required to release the antigen from bentonite. Acidification of the detergent solution precipitates the active solution precipitates the active protein. Extraction of heme from the acidified detergent precipitate by methyl-ethyl ketone further purifies the antigen. This acid detergent treatment eliminates the need to use bentonite as a purification step