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Fusogenic effects of murine retroviruses and cationic enhancers of transduction
1Creighton Cancer Center/Department of Biomedical Sciences, Creighton University School of Medicine, Omaha, Nebraska 68178, USA.
Abstract:
The maturation of retrovirus particles involves proteolytic cleavage of the envelope glycoprotein transmembrane component, resulting in conversion of the virus particle to a fusogenic or infectious state. Susceptible murine cells exposed to virus-containing supernatants from ecotropic retroviral helper cells occasionally fused to neighboring cells, resulting in syncytia (giant cells with multiple nuclei). Polycationic molecules dramatically enhanced the effect, leading to widespread cell death. The degree of cell fusion was dependent upon the retroviral envelope subtype (ecotropic-->amphotropic, gibbon ape leukemia virus was negative) as well as on the polycationic reagent used (G9 dendrimer-->Lipofectamine-->polybrene). Cell fusion effects were not mediated by the retroviral vector backbone, because virus-containing supernatants from helper cells (without vector) and vector producer cells had a similar effect. Human target cells were not fused by any type of murine retrovirus; in addition, amphotropic virus from human helper cells was not fusogenic toward murine cells. Thus, fusogenic effects were important during the propagation of vectors using murine helper cells but were not a significant factor during the transduction of human cells.
Insights
Retrovirus maturation causes cell fusion, especially with polycationic molecules. These cell fusion effects are specific to murine cells and retroviral envelope subtypes, not impacting human cell transduction.
Area of Science:
- Retroviral biology
- Cellular fusion mechanisms
- Gene therapy vectors
Background:
- Retrovirus maturation requires envelope glycoprotein cleavage, converting particles to a fusogenic state.
- Murine cells exposed to retroviral supernatants can undergo fusion, forming syncytia.
- Polycationic molecules significantly enhance retroviral-mediated cell fusion and cell death.
Purpose of the Study:
- To investigate the factors influencing retroviral-mediated cell fusion in murine and human cells.
- To determine the role of retroviral envelope subtype and polycationic reagents in cell fusion.
- To assess the significance of fusogenic effects during vector propagation and cell transduction.
Main Methods:
- Exposure of susceptible murine and human cells to virus-containing supernatants from retroviral helper cells.
- Treatment with various polycationic molecules (G9 dendrimer, Lipofectamine, polybrene).
- Comparison of fusion effects across different retroviral envelope subtypes and cell types.
Main Results:
- Cell fusion and syncytia formation were observed in murine cells, significantly enhanced by polycationic molecules.
- Fusion efficiency varied with retroviral envelope subtype (ecotropic > amphotropic) and polycationic reagent.
- Human cells showed no fusion with murine retroviruses, and murine cells showed no fusion with amphotropic human retroviruses.
Conclusions:
- Fusogenic effects are critical during the propagation of retroviral vectors using murine helper cells.
- These cell fusion phenomena are specific to the retroviral envelope and host cell type.
- Fusogenic effects are not a significant factor in the transduction of human cells by murine retroviruses.
