Investigating Tick-borne Flaviviral-like Particles as a Delivery System for Gene Therapy

Anne H Neddermeyer; Kjell Hultenby; Maruthibabu Paidikondala; Ryan M Schuchman; Mehdi R M Bidokhti

doi:10.1016/j.curtheres.2017.10.003

Investigating Tick-borne Flaviviral-like Particles as a Delivery System for Gene Therapy

Curr Ther Res Clin Exp. 2017 Oct 16:88:8-17. doi: 10.1016/j.curtheres.2017.10.003. eCollection 2018.

Authors

Anne H Neddermeyer¹, Kjell Hultenby², Maruthibabu Paidikondala³, Ryan M Schuchman⁴, Mehdi R M Bidokhti⁴

Affiliations

¹ Department of Medical Sciences, Uppsala University, Uppsala 751 85, Sweden.
² Department of Laboratory Medicine, Clinical Research Center, Karolinska Institute, Stockholm 141 86, Sweden.
³ Department of Chemistry - Ångström Laboratory, Uppsala University, Uppsala 75120, Sweden.
⁴ Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, North Carolina 27695, USA.

Abstract

Background: Research on the biogenesis of tick-borne encephalitis virus (TBEV) would benefit gene therapy. Due to specific arrangements of genes along the TBEV genome, its viral-like particles (VLPs) could be exploited as shuttles to deliver their replicon, which carries therapeutic genes, to immune system cells.

Objective: To develop a flaviviral vector for gene delivery as a part of gene therapy research that can be expressed in secretable VLP suicidal shuttles and provide abundant unique molecular and structural data supporting this gene therapy concept.

Method: TBEV structural gene constructs of a Swedish Torö strain were cloned into plasmids driven by the promoters CAG and CMV and then transfected into various cell lines, including COS-1 and BHK-21. Time-course sampling of the cells, culture fluid, cell lysate supernatant, and pellet specimens were performed. Western blotting and electron microscopy analyses of collected specimens were used to investigate molecular and structural processing of TBEV structural proteins.

Results: Western blotting analysis showed differences between promoters in directing the gene expression of the VLPs constructs. The premature flaviviral polypeptides as well as mature VLPs could be traced. Using electron microscopy, the premature and mature VLP accumulation in cellular compartments-and also endoplasmic reticulum proliferation as a virus factory platform-were observed in addition to secreted VLPs.

Conclusions: The abundant virologic and cellular findings in this study show the natural processing and safety of inserting flaviviral structural genes into suicidal VLP shuttles. Thus, we propose that these VLPs are a suitable gene delivering system model in gene therapy.

Keywords: CAG promoter; CMV promoter; delivery system; electron microscopy; flavivirus; gene therapy; tick-borne encephalitis virus; viral-like particles.