Immunogenicity of targeted lentivectors.

Area of Science:

• Immunology
• Vaccinology
• Gene Therapy

Background:

• Lentiviral vectors (LVs) are being explored as anti-cancer vaccines.
• Nanobody (Nb) display technology was developed to target LVs to antigen-presenting cells (APCs).
• Conventional dendritic cells (DCs) are hypothesized as key APCs for anti-tumor immunity.

Purpose of the Study:

• To investigate the efficacy of targeting LVs exclusively to conventional DCs.
• To compare the immunogenicity of DC-subtype targeted LVs against other LV types.
• To evaluate LV safety and efficacy as anti-cancer vaccines.

Main Methods:

• Development of Nanobody (Nb) display technology for LV targeting.
• Comparison of LVs targeted to conventional DCs, general APCs, broad tropism, and non-infectious LVs.
• Intranodal immunization with ovalbumin encoding LVs and analysis of T cell responses (CD4+ T cell proliferation, cytokine secretion, CTL stimulation).

Main Results:

• All LV types induced CD4+ T cell proliferation, but conventional DC targeting yielded a less potent TH1 profile compared to general APC or broad tropism LVs.
• Conventional DC targeting showed a less potent TH1 profile than non-infectious LVs, contradicting the hypothesis of their primary importance.
• Targeted LVs stimulated cytotoxic T lymphocytes (CTLs), with APC-targeted LVs demonstrating comparable therapeutic potency to broad tropism LVs.

Conclusions:

• Targeting conventional DCs alone for LV-based vaccines may not be optimal for inducing a strong TH1 anti-tumor immune response.
• Activation of a broader range of APCs appears meaningful for effective anti-tumor immunity.
• APC-targeted LVs offer a promising alternative as safer and efficacious LV-based vaccines.