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Measurement of Gross cell-surface antigen and p30 level in murine retrovirus-infected cell lines
Abstract:
The level of Gross cell-surface antigen (GCSAa) expression at the surface of murine retrovirus-infected fibroblasts was determined by quantitative absorption of the anti-GCSAa activity of a serum produced in syngeneic W/Fu rats immunized against (C58NT)D lymphoma, and tested in a cytotoxicity assay against E male G2 lymphoma cells. While GCSAa was specifically expressed on Gross-type virus (G-MuLV)-induced lymphoma cells, and while G-MuLV and G-related MuLV induced a high level of GCSAa expression on murine fibroblasts, the Friend-Moloney-Rauscher (FMR) group viruses (FMR MuLV) and xenotropic isolates were also able to induce a high or intermediate level of GCSAa. Since GCSAa has been shown to be borne by glycosylated precursors of the viral nucleocapside (gp95gag and gp85gag), the amount of GCSAa expressed on these cells was compared to the level of cytoplasmic p30. In G- and G-related MuLV-infected cell lines, a significant relationship was found between the amount of GCSAa and the level of p30, whereas in FMR-MuLV or xenotropic virus-infected cells the amount of GCSAa varied independently of the p30 level. These results could explain the discrepancy in the specificity of expression of GCSAa in vivo and in vitro.
Insights
Gross cell-surface antigen (GCSAa) expression on murine fibroblasts varies depending on the infecting retrovirus. G-MuLV and related viruses show a direct correlation with p30 levels, unlike FMR or xenotropic viruses.
Area of Science:
- Virology
- Immunology
- Cell Biology
Background:
- Gross cell-surface antigen (GCSAa) is expressed on murine retrovirus-infected cells.
- GCSAa is associated with glycosylated precursors of the viral nucleocapsid (gp95gag and gp85gag).
- Discrepancies exist in the in vivo and in vitro specificity of GCSAa expression.
Purpose of the Study:
- To quantify GCSAa expression on murine retrovirus-infected fibroblasts.
- To compare GCSAa expression levels with cytoplasmic p30 levels in different virus-infected cells.
- To investigate the relationship between GCSAa expression and viral groups.
Main Methods:
- Quantitative absorption of anti-GCSAa activity using syngeneic rat serum.
- Cytotoxicity assays against specific lymphoma cell lines.
- Comparison of GCSAa surface expression with cytoplasmic p30 levels.
Main Results:
- Gross-type virus (G-MuLV) and related MuLV induced high GCSAa expression on fibroblasts.
- Friend-Moloney-Rauscher (FMR) MuLV and xenotropic isolates also induced GCSAa expression, but with varying levels.
- A significant correlation between GCSAa and p30 was observed in G-MuLV and related MuLV-infected cells, but not in FMR-MuLV or xenotropic virus-infected cells.
Conclusions:
- The level of GCSAa expression on murine fibroblasts is influenced by the specific retrovirus involved.
- The independent variation of GCSAa from p30 levels in FMR-MuLV and xenotropic virus infections may explain observed expression discrepancies.
- Findings contribute to understanding the differential regulation of viral antigen expression in vitro.