ABSTRACT
Simian sarcoma-associated virus (SSaV) was repeatedly passaged on three human cell lines. The proteins of the progeny virus were analysed for the presence of variant polypeptides. Occasionally, a few variant polypeptides were observed. One-dimensional peptide maps of the major virus protein p30 revealed no modifications after 25 cycles of infection on the three cell lines studied. The peptide map of Pr65gag of virus grown through 25 passages on a human chondrosarcoma cell line was slightly different from that of the virus stock before passaging. The relative amount of the virus protein p30 as compared to p18 and p16 (possibly the SSaV equivalents of p15E and p12E) was variable depending on the host cell. Virus grown on Daudi cells was relatively deficient in p18 and p16. These virus particles were morphologically altered and had a low infectivity.