SV40 tumor rejection induced by vesicular stomatitis virus bearing SV40 tumor-specific transplantation antigen (SV40-TSTA). II. Association of SV40-TSTA activity with liposomes containing VSV glycolipids.

Highly purified vesicular stomatitis virus (VSV) was obtained from VSV-infected SV40-transformed and from "normal" hamster cell lines. A glycolipid extract was prepared from these VSV preparations according to the Folch partition procedure. These glycolipids were rendered immunogenic to the Syrian hamsters when incorporated within liposomal membranes composed of lecithin/sphingomyelin/cholesterol (1/1/2 by weight). When the glycolipids were extracted from VSV grown on cell lines (TSV5-cl2 and EHSVi-cl1) which contained the SV40 tumor-specific transplantation antigen (SV40-TSTA), it was possible either to induce a tumor rejection or at least to slow the growth of the tumor in Syrian hamsters challenged with TSV5-cl2 cells. No protection was obtained in animals treated with liposomes containing glycolipids extracted from purified VSV grown on SV40-TSTA-negative cells (EHB). The SV40-TSTA could be a glycolipid of the transformed cell membrane which is incorporated within the VSV envelope.