Summary auto-generated
This study demonstrates the presence of a specific tumor antigen induced by chick embryo lethal orphan (CELO) virus in hamster tumors. Researchers inoculated newborn hamsters with CELO virus and established a tumor-derived cell line from animals that developed tumors. Tumor antigen was prepared from transplanted tumors and tested using complement-fixation and immunofluorescence assays against sera from tumor-bearing hamsters. The CELO tumor antigen showed specific reactivity with homologous serum (titre 1/32 by complement-fixation) but did not cross-react with antigens from tumors induced by SV40 or adenovirus 12, or with normal hamster serum. Immunofluorescence studies revealed specific granular nuclear fluorescence in 100% of CELO tumor cells treated with homologous serum, with no cross-reactivity against tumor cells from other viral origins. The findings confirm that CELO virus induces an immunologically distinct tumor antigen, similar to those previously described for polyoma virus, SV40, and oncogenic adenoviruses. The antigen was detectable only in tumor cells extensively subcultured in vitro, explaining earlier negative results with early passage cells.
Key findings
- CELO virus induces a specific tumor antigen in hamster tumors that is immunologically distinct from tumor antigens produced by SV40 and adenovirus 12
- The tumor antigen was detected by complement-fixation (titre 1/32) and immunofluorescence with no cross-reactivity to other viral tumor antigens
- Specific granular nuclear fluorescence was observed in 100% of CELO tumor cells using homologous antiserum from tumor-bearing hamsters
- The tumor antigen was only detectable in tumor cells that had undergone extensive in vitro passage, not in early passage cells
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Abstract
The cells of tumours induced in laboratory animals by the inoculation of DNA viruses contain antigens, termed tumour antigens, not present in normal cells (Huebner, 1967; Macpherson, 1967). These antigens are specific for the tumour-inducing virus, and have been described in tumour cells induced by polyoma virus (Habel, 1965), simian virus SV40 (Black et al. 1963) and the oncogenic adenoviruses of human, simian, bovine, dog and mouse origin (Huebner, 1967). Sarma, Huebner & Lane (1965) reported the induction of tumours in newborn hamsters by chick embryo lethal orphan (CELO) virus. This preliminary report describes a tumour antigen specific for CELO virus.
The PHELPS strain of CELO virus (Petek, Felloga & Zolletto, 1963) was used to inoculate the allantoic cavity of 7-day chick embryos. After 5 days' incubation at 36° the allantoic fluids were harvested, pooled and stored at -80°. This stock virus pool had a titre of 108.5 TCD 50/ml. in tissue cultures of chick kidney cells (Chomiak, Luginbuhl & Helmboldt, 1961).