Strain-specific antigen of the avian leukosis sarcoma virus group: I. Isolation and immunological characterization

Abstract From each of three strains of avian leukosis sarcoma viruses—avian myeloblastosis virus BAI strain A (AMV), myeloblastosis associated virus strain B (MAV-B), and Schmidt-Ruppin Rous sarcoma virus 1 (SR-RSV-1)—an antigenic component was extracted by treatment with Tween 20 detergent. The isolated antigen is believed to represent strain-specific antigen of the viral envelope (V e antigen) because of various properties: (1) In the agar gel double diffusion test, the antigen reacts with neutralizing chicken antisera to the original virus, but not with normal chicken sera or with chicken antisera to viruses unrelated in their envelope antigenicity to the agent from which the antigen was isolated. (2) The antigen absorbs neutralizing antibody of homologous chicken antiserum, but not of antisera prepared against serologically unrelated virus. (3) A rabbit immune serum against antigen isolated from MAV-B neutralizes MAV-B and other subgroup B viruses, but not subgroup A virus. (4) The antigen obtained from MAV-B induces early interference to subgroup B viruses, but not to subgroup A viruses. The antigenicity of the V e antigen is completely lost after incubation with 0.1 mg of trypsin or 1 mg of α-chymotrypsin per milliliter, and is partially inactivated by treatment with 0.5 mg of papain per milliliter. Some phospholipid- and polysaccharide-digesting enzymes and two other detergents do not cause decrease of the V e antigenicity.