Production of primate D-type virus interspecies-specific antigen during cocultivation of human breast fibroadenoma cells with bat lung cells.

Nine human breast fibroadenomas, initially negative for D-type retrovirus interspecies-specific antigen, do not produce that antigen during 6 months of cocultivation with bat lung cells. However, 3 out of 5 human breast fibroadenomas, already positive for D-type virus interspecies-specific antigen before cultivation, are able to induce a transient D-type retrovirus interspecies-specific antigen production after 3 to 4 months of cocultivation with bat lung cells. The antigen is detectable both in cocultivated cells and in pellets sedimented from the coculture fluid. It is concluded that D-type retroviruses are associated with human breast fibroadenomas.