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Ecotropic murine leukemia virus-induced fusion of murine cells
Abstract:
Extensive fusion occurs upon cocultivation of murine fibroblasts producing ecotropic murine leukemia viruses (MuLVs) with a large variety of murine cell lines in the presence of the polyene antibiotic amphotericin B, the active component of the antifungal agent Fungizone. The resulting polykaryocytes contain nuclei from both infected and uninfected cells, as evidenced by autoradiographic labeling experiments in which one or the other parent cell type was separately labeled with [3H]thymidine and fused with an unlabeled parent. This cell fusion specifically requires the presence of an ecotropic MuLV-producing parent and is not observed for cells producing xenotropic, amphotropic, or dualtropic viruses. Mouse cells infected with nonecotropic viruses retain their sensitivity toward fusion, whereas infection with ecotropic viruses abrogates the fusion of these cells upon cocultivation with other ecotropic MuLV-producing cells. Nonmurine cells lacking the ecotropic gp70 receptor are not fused under similar conditions. Fusion is effectively inhibited by monospecific antisera to gp70, but not by antisera to p15(E), and studies with monoclonal antibodies identify distinct amino- and carboxy-terminal gp70 regions which play a role in the fusion reaction. The enhanced fusion which occurs in the presence of amphotericin B provides a rapid and sensitive assay for the expression of ecotropic MuLVs and should facilitate further mechanistic studies of MuLV-induced fusion of murine cells.
Insights
Ecotropic murine leukemia viruses (MuLVs) induce extensive cell fusion in murine cells, enhanced by amphotericin B. This fusion requires the ecotropic gp70 receptor and is inhibited by specific antibodies, aiding in MuLV detection.
Area of Science:
- Virology
- Cell Biology
- Molecular Biology
Background:
- Murine leukemia viruses (MuLVs) are retroviruses that can infect mouse cells.
- Cell fusion is a process where cells merge to form a larger cell or syncytium.
- Understanding viral mechanisms of cell fusion is crucial for virology research.
Purpose of the Study:
- To investigate the mechanism of cell fusion induced by ecotropic MuLVs.
- To identify the viral and cellular factors involved in MuLV-induced cell fusion.
- To develop a sensitive assay for detecting ecotropic MuLV expression.
Main Methods:
- Cocultivation of MuLV-producing murine fibroblasts with various murine cell lines in the presence of amphotericin B.
- Autoradiographic labeling with [3H]thymidine to track nuclei during fusion.
- Inhibition studies using antisera and monoclonal antibodies against viral glycoproteins (gp70, p15(E)).
Main Results:
- Extensive cell fusion occurred specifically with ecotropic MuLV-producing cells, forming polykaryocytes.
- Fusion requires the presence of the ecotropic gp70 receptor on target cells.
- Antisera to gp70 inhibited fusion, identifying specific gp70 regions involved.
Conclusions:
- Ecotropic MuLV-induced cell fusion is mediated by the gp70 envelope protein.
- Amphotericin B enhances this fusion, providing a sensitive assay for ecotropic MuLV detection.
- This finding facilitates further studies into MuLV-mediated cell fusion mechanisms.