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Differential target cell susceptibility to SFV-immune cytotoxic T-cells
1Division of Cell Biology, John Curtin School of Medical Research, Australian National University, Canberra, A.C.T.
Abstract:
Semliki Forest virus (SFV) infects a variety of murine cell types of H-2k haplotype. However, only L929 fibroblasts can be productively infected. Thioglycollate-induced peritoneal macrophages (TGM), and BW 5147 thymoma cells can be infected with SFV as demonstrated by SFV antigen expression on the cell surface and intracellularly. SFV-immune cytotoxic T (Tc) cells lyse only infected TGM and L929 target cells, however different times after infection are required for lysis of these two cell types. Split clone limiting dilution and cold target competition experiments are consistent with the interpretation that these two cell types display qualitatively different epitopes to SFV-immune Tc cells but do not exclude additional quantitative differences.
Insights
Semliki Forest virus (SFV) infects multiple murine cells, but only L929 fibroblasts support full infection. Cytotoxic T cells target infected macrophages and fibroblasts, suggesting distinct viral antigen presentation.
Area of Science:
- Virology
- Immunology
- Cell Biology
Background:
- Semliki Forest virus (SFV) infects various murine cells with H-2k haplotype.
- Productive infection is typically limited to L929 fibroblasts.
- Other cell types, like macrophages and thymoma cells, can be infected but may not support full replication.
Purpose of the Study:
- To investigate the differential susceptibility of murine cell types to Semliki Forest virus (SFV) infection.
- To analyze the recognition of infected cells by SFV-immune cytotoxic T (Tc) cells.
- To understand the nature of viral antigen presentation on different infected cell types.
Main Methods:
- Infection of murine cell types (L929 fibroblasts, thioglycollate-induced peritoneal macrophages (TGM), BW 5147 thymoma cells) with SFV.
- Detection of SFV antigen expression on cell surfaces and intracellularly.
- Cytotoxicity assays using SFV-immune Tc cells against infected target cells.
- Split clone limiting dilution and cold target competition experiments.
Main Results:
- SFV antigen expression was observed in infected L929 fibroblasts, TGM, and BW 5147 thymoma cells.
- SFV-immune Tc cells effectively lysed infected L929 fibroblasts and TGM.
- Differential kinetics of lysis were observed for TGM and L929 fibroblasts.
- Experiments suggest qualitatively different viral epitopes are presented by TGM and L929 cells to Tc cells.
Conclusions:
- Murine cell types exhibit varying capacities for productive SFV infection.
- SFV-immune cytotoxic T cells recognize infected macrophages and fibroblasts, but with distinct temporal profiles.
- Differences in epitope presentation likely account for the varied T cell responses, with potential quantitative variations also contributing.