title: Human teratocarcinomas cultured in vitro produce unique retrovirus-like viruses.
abstract: We have previously reported that among a series of human tumours investigated, only human teratocarcinoma cell lines derived from testicular tumours or pulmonary metastases of patients in Germany and the U.S.A. produced retrovirus-like particles spontaneously, albeit in low amounts. In a recent publication electron microscopical data suggested that the human teratocarcinoma-derived ( HTD ) particles were morphologically closely related, but not identical, to the type C retroviruses of animals. In this communication, the explantation of three human teratocarcinoma cell lines is briefly described. Evidence is presented that HTD particles (i) are synthesized only in a fraction of the epithelioid and differentiating cells; (ii) can be induced biochemically in a manner characteristic of retroviruses; (iii) either are not infectious or possess a peculiar host range; (iv) are immunologically unrelated to animal retrovirus strains; (v) possess an endogenous RNA-dependent DNA polymerase activity that can be banded at 1.16 g/ml in linear sucrose gradients. These results may be taken as suggestive evidence that HTD particles represent a novel group of unique retroviruses.
mesh_terms: D000956:Antigens, Viral / Q000032:analysis; D002455:Cell Division; D046508:Culture Techniques; D006801:Humans; D008854:Microscopy, Electron; D012194:RNA-Directed DNA Polymerase / Q000032:analysis; D012190:Retroviridae / Q000201:enzymology / Q000276:immunology / Q000302:isolation & purification* / Q000648:ultrastructure; D013724:Teratoma / Q000382:microbiology*; D014779:Virus Replication
chemical_list: D000956:Antigens, Viral; D012194:RNA-Directed DNA Polymerase