Detection of oncornavirus‐like particles in HeLa cells. I. Fine structure and comparative morphological classification

Abstract

Abstract Oncornavirus‐like particles have been consistently observed over a period of 3 years in HeLa cells obtained from several laboratories. The particles mature by budding, in that previously fully assembled A‐type‐like particles are enveloped by the protruding cell membrane with subsequent release of the virion. When compared morphologically to B‐ and C‐type particles, distinct differences were observed; however, the HeLa particles closely resemble two primate viruses, namely the Mason‐Pfizer monkey virus and a recently discovered virus derived from human brain cells. HeLa particles demonstrate a narrow host range. Thus a new morphological group of viruses emerges that might be specific for primates.