An oncornavirus isolated from human cancer cell line

A virus has been isolated from a clone of continuous cell line that was derived from human cancer tissue (HEp-2 cells). The clone of HEp-2 cells retains human Karyotype and has no heterogeneous contamination. Injection of the cells and the virus into mice of C3H/Sn, C3H/H2P, BaLB/c lines and into newborn hamsters did not produce tumors in animals. Intracellular virus possesses morphological characteristics of oncornaviruses type A and B; extracellular virus has the properties of oncornaviruses type B. The virus bands at ϱ = 1.16 g/ml in sucrose density gradients, and the production of it is inhibited by actinomycin D. The virions contain reverse transcriptase, and the products of reaction are double-stranded DNA and RNA:DNA hybrids. The virus is immunologically distinct from mouse mammary tumor virus. Possible human origin of the virus is discussed.