Retrovirus like particles produced by human embryonal cells and cell lines derived from human malignancies. II. Protein structure.

Very small amounts of retrovirus-like particles were isolated from tissue culture media of various types of human cell lines derived from malignant as well as normal cells. The aim of the present study is the characterization of protein profiles of these isolates. The comparison of protein profiles of isolated human virus-like particles with the profiles of well characterized animal as well as human exogenous (LAV/HTLV-III) retroviruses revealed a 25k protein (p25) to be a major protein or at least one of the protein components of human retrovirus-like particles.