Propagating and Detecting an Infectious Molecular Clone of Maedi-visna Virus that Expresses Green Fluorescent Protein
Summary
We describe a molecular clone of maedi-visna virus that expresses GFP and is fully infectious. Replication of this virus can be detected by using fluorescence microscopy and flow cytometry.
Abstract
Maedi-visna virus (MVV) is a lentivirus of sheep, causing slowly progressive interstitial pneumonia and encephalitis1. The primary target cells of MVV in vivo are considered to be of the monocyte lineage2. Certain strains of MVV can replicate in other cell types, however3,4. The green fluorescent protein is a commonly used marker for studying lentiviruses in living cells. We have inserted the egfp gene into the gene for dUTPase of MVV. The dUTPase gene is well conserved in most lentivirus strains of sheep and goats and has been shown to be important in replication of CAEV5. However, dUTPase has been shown to be dispensable for replication of the molecular clone of MVV used in this study both in vitro and in vivo6. MVV replication is strictly confined to cells of sheep or goat origin. We use a primary cell line from the choroid plexus of sheep (SCP cells) for transfection and propagation of the virus7. The fluorescent MVV is fully infectious and EGFP expression is stable over at least 6 passages8. There is good correlation between measurements of TCID50 and EGFP. This virus should therefore be useful for rapid detection of infected cells in studies of cell tropism and pathogenicity in vitro and in vivo8.
Protocol
Discussion
The GFP expressing molecular clone of MVV presented here should be useful for analyzing the host-cell interactions and pathogenicity of MVV both in vitro and in vivo. The virus obtained after 7-14 days of replication has undoubtedly acquired some mutations due to the inaccuracy of reverse transcriptase. However, there are limitations to the use of this clone as a single cycle vector. One is that use of the clone is restricted to cells of sheep and goat origin. The transfection efficiency of these cells using our construc…
Disclosures
The authors have nothing to disclose.
Acknowledgements
This work was funded by the Icelandic Research Fund and the University of Iceland Research Fund.
Materials
| Name of the reagent | Company | Catalogue number |
| DMEM | Gibco | 10938025 |
| Opti-MEM | Gibco | 51985018 |
| Lipofectamine 2000 | Invitrogen | 11668019 |
References
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