A murine leukemia virus with Cre-LoxP excisible coding sequences allowing superinfection, transgene delivery, and generation of host genomic deletions

Clifford L Wang,Matthias Wabl,Tiffany Malek,Finn Pedersen,J Graeme Hodgson

doi:10.1186/1742-4690-1-5

Abstract

BackgroundTo generate a replication-competent retrovirus that could be conditionally inactivated, we flanked the viral genes of the Akv murine leukemia virus with LoxP sites. This provirus can delete its envelope gene by LoxP/Cre mediated recombination and thereby allow superinfection of Cre recombinase expressing cells.ResultsIn our studies, the virus repeatedly infected the cell and delivered multiple copies of the viral genome to the host genome; the superinfected cells expressed a viral transgene on average twenty times more than non-superinfected cells. The insertion of multiple LoxP sites into the cellular genome also led to genomic deletions, as demonstrated by comparative genome hybridization.ConclusionWe envision that this technology may be particularly valuable for delivering transgenes and/or causing deletions.

Highlights

To generate a replication-competent retrovirus that could be conditionally inactivated, we flanked the viral genes of the Akv murine leukemia virus with LoxP sites
Because the virus can randomly distribute LoxP sites over the host genome, we investigated the potential of the virus for deletional mutagenesis
We flanked the envelope gene with two LoxP sites so that it could be excised by Cre recombinase

Summary

Introduction

To generate a replication-competent retrovirus that could be conditionally inactivated, we flanked the viral genes of the Akv murine leukemia virus with LoxP sites. This provirus can delete its envelope gene by LoxP/Cre mediated recombination and thereby allow superinfection of Cre recombinase expressing cells. In addition to being a component of burgeoning viruses, the envelope is believed to bind to the cellular receptor of the virus, either intracellularly or at the cell membrane This interaction prevents adequate surface display of the receptor, without which other retroviruses dependent on the same receptor cannot enter and infect the cell [8,9,10]. While gammaretroviral packaging cell lines can be manipulated to generate a high multiplicity of infection in cell culture [11,12], it may be useful, especially for studies in animal models, to have a retrovirus that circumvents superinfection barriers without such lines

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