Immunogenicity of targeted lentivectors
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Cleo Goyvaerts1, De Groeve Kurt2,3, Sandra Van Lint1, Carlo Heirman1, Jo A. Van Ginderachter2,3, Patrick De Baetselier2,3, Geert Raes2,3, Kris Thielemans1 and Karine Breckpot1
1 Laboratory of Molecular and Cellular Therapy, Department of Immunology-Physiology, Vrije Universiteit Brussel, Brussels, Belgium
2 Laboratory of Cellular and Molecular Immunology, Vrije Universiteit Brussel, Brussels, Belgium
3 Laboratory of Myeloid Cell Immunology, VIB, Brussels, Belgium
Karine Breckpot, email:
Keywords: lentivector, targeting, antigen presenting cell, vaccine, antitumor immunotherapy
Received: December 13, 2013 Accepted: January 17, 2014 Published: January 19, 2014
To increase the safety and possibly efficacy of HIV-1 derived lentivectors (LVs) as an anti-cancer vaccine, we recently developed the Nanobody (Nb) display technology to target LVs to antigen presenting cells (APCs). In this study, we extend these data with exclusive targeting of LVs to conventional dendritic cells (DCs), which are believed to be the main cross-presenting APCs for the induction of a TH1-conducted antitumor immune response. The immunogenicity of these DC-subtype targeted LVs was compared to that of broad tropism, general APC-targeted and non-infectious LVs. Intranodal immunization with ovalbumin encoding LVs induced proliferation of antigen specific CD4+ T cells, irrespective of the LVs’ targeting ability. However, the cytokine secretion profile of the restimulated CD4+ T cells demonstrated that general APC targeting induced a similar TH1-profile as the broad tropism LVs while transduction of conventional DCs alone induced a similar and less potent TH1 profile as the non-infectious LVs. This observation contradicts the hypothesis that conventional DCs are the most important APCs and suggests that the activation of other APCs is also meaningful. Despite these differences, all targeted LVs were able to stimulate cytotoxic T lymphocytes, be it to a lesser extent than broad tropism LVs. Furthermore this induction was shown to be dependent on type I interferon for the targeted and non-infectious LVs, but not for broad tropism LVs. Finally we demonstrated that the APC-targeted LVs were as potent in therapy as broad tropism LVs and as such deliver on their promise as safer and efficacious LV-based vaccines.
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