Oncornavirus-like particles in malignant melanoma and control biopsies

Tests for the presence of oncornavirus-like particles in human biopsies were made by the Spiegelman simultaneous assay for 70S RNA and RNA-dependent DNA polymerase and by detection of 600-900S particles, incorporating 3H-uridine, produced by cultured biopsy cells. Thirty-one malignant melanoma biopsies from 29 patients were studied. Using the simultaneous assay, evidence of virus-like particles was found in 15/26 (58%) of melanoma biopsies, 0/3 naevi pools, 1/4 samples of skin adjacent to melanoma, 0/3 samples of normal adult skin and 0/3 prepuces. The velocity sedimentation technique was shown to be a useful screening test for oncornaviruses in studies of two virus-producing mouse cell lines (TKL-5 and WEHI-22), and was positive with 7/9 melanoma biopsies. Overall, these results are compatible with the earlier findings of similar virus-like particles in malignant melanoma cell lines, but the exact nature of the particles remains to be defined.