Avian retrovirus-induced surface antigens and their cross-reactivity with chemically-transformed cells and primary embryonic cells of Japanese quails.

By testing spleen cells from avian leukosis (ALV) and avian sarcoma virus (ASV)-injected Japanese quails in a microcytotoxicity assay against various target cells, we have demonstrated the existence of several target antigens. With non-transformed ALV-infected Japanese quail cells used as target cells, an avian retrovirus subgroup-specific destruction was obtained when spleen cells from animals infected with either avaian sarcoma or leukosis virus of the same subgroup were employed. This reaction is probably due to the virus envelope glycoproteins (Ve-gp) expressed on the cell surface. Apart from this subgroup-specific reaction, avian retrovirus group-specific destruction of ASV-transformed cells was demonstrated by means of effector cells immunized with ASV of a different subgroup. This reaction is restricted to transformed cells and not due to the virus envelope glycoprotein because the same effector cells are not cytotoxic to ALV-infected non-transformed cells but cytotoxic to sarcoma-virus-transformed cells which lack Ve-gp. Quail methylcholanthrene-tumor cells which show a transformation phenotype similar to that of ASV-transformed cells but which are free of detectable endogenous and exogenous retrovirus were also destroyed by the spleen cells from ASV tumorbearing animals. The same effector cells also exerted a weak cytotoxic effect on uninfected primary embryo cells but not to embryo cells after several passages.