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A novel gene therapy strategy using secreted multifunctional anti-HIV proteins to confer protection to gene-modified and unmodified target cells

Gene Therapy volume 21, pages 175–187 (2014)Cite this article

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Abstract

Current human immunodeficiency virus type I (HIV) gene therapy strategies focus on rendering HIV target cells non-permissive to viral replication. However, gene-modified cells fail to accumulate in patients and the virus continues to replicate in the unmodified target cell population. We have designed lentiviral vectors encoding secreted anti-HIV proteins to protect both gene-modified and unmodified cells from infection. Soluble CD4 (sCD4), a secreted single chain variable fragment (sscFv17b) and a secreted fusion inhibitor (sFIT45) were used to target receptor binding, co-receptor binding and membrane fusion, respectively. Additionally, we designed bi- and tri-functional fusion proteins to exploit the multistep nature of HIV entry. Of the seven antiviral proteins tested, sCD4, sCD4-scFv17b, sCD4-FIT45 and sCD4-scFv17b-FIT45 efficiently inhibited HIV entry. The neutralization potency of the bi-functional fusion proteins sCD4-scFv17b and sCD4-FIT45 was superior to that of sCD4 and the Food and Drug Administration-approved fusion inhibitor T-20. In co-culture experiments, sCD4, sCD4-scFv17b and sCD4-FIT45 secreted from gene-modified producer cells conferred substantial protection to unmodified peripheral blood mononuclear cells. In conclusion, continuous delivery of secreted anti-HIV proteins via gene therapy may be a promising strategy to overcome the limitations of the current treatment.

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Acknowledgements

We are grateful to several colleagues for generously providing us with various reagents: Dr Branch for pJRFL-env and HIVIIIB; Dr Moffat for pLJM2, psPAX2, pMD2.G and 293T cells; and Dr Ostrowski for PBMCs and HIVNL4-3. We also thank Waqar Ahmad and Jimmy Chen for their help with some of the experiments. This research is funded by Canadian Institutes for Health Research (Grant number HOP-93433).

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Authors and Affiliations

  1. Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada

    A Falkenhagen, S E Read & S Joshi

  2. Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada

    M Ameli & S Joshi

  3. Department of Pediatrics, The Hospital for Sick Children, Toronto, ON, Canada

    S Asad & S E Read

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  1. A Falkenhagen
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Correspondence to S Joshi.

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Falkenhagen, A., Ameli, M., Asad, S. et al. A novel gene therapy strategy using secreted multifunctional anti-HIV proteins to confer protection to gene-modified and unmodified target cells. Gene Ther 21, 175–187 (2014). https://doi.org/10.1038/gt.2013.70

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