Role of TLR3 in the immunogenicity of replicon plasmid-based vaccines

• Published in: Gene therapy Vol. 16; no. 3; pp. 359 - 366
• Main Authors: Diebold, S S, Schulz, O, Alexopoulou, L, Leitner, W W, Flavell, R A, Reis e Sousa, C
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01-03-2009; Nature Publishing Group
• Subjects: Alphavirus; Anesthesia. Intensive care medicine. Transfusions. Cell therapy and gene therapy; Animals; Apoptosis - immunology; Applied cell therapy and gene therapy; Biological and medical sciences; Biomedical and Life Sciences; Biomedicine; Biotechnology; CD8 Antigens - analysis; CD8-Positive T-Lymphocytes - immunology; Cell Biology; Cell receptors; Cercopithecus aethiops; Coculture Techniques; Cytotoxicity; Cytotoxicity, Immunologic - immunology; Dendritic cells; Dendritic Cells - immunology; Deoxyribonucleic acid; DNA; DNA replicase; DNA vaccines; Double-stranded RNA; Fundamental and applied biological sciences. Psychology; Gene Expression; Gene Expression - immunology; Gene Therapy; Genes, Transgenic, Suicide; Genetic aspects; Genetic Vectors - immunology; Health aspects; Health. Pharmaceutical industry; Human Genetics; Immune response; Immunogenicity; Industrial applications and implications. Economical aspects; Interferon; Intermediates; Lymphocytes T; Medical sciences; Mice; Mice, Inbred C57BL; Mice, Knockout; mRNA; Nanotechnology; original-article; Physiological aspects; Plasmids; Plasmids - immunology; Replicase; Replicon - immunology; Ribonucleic acid; RNA; RNA, Double-Stranded - biosynthesis; RNA-directed RNA polymerase; Rodents; Spleen - immunology; TLR3 protein; Toll-Like Receptor 3 - immunology; Toll-like receptors; Transfection; Transfusions. Complications. Transfusion reactions. Cell and gene therapy; Vaccination - methods; Vaccines; Vaccines, DNA - immunology; Vero Cells; United Kingdom; Toll-like receptors; dendritic cells; double-stranded RNA; replicon vaccines; Dendritic cell; Double stranded RNA; Natural immunity; Toll like receptor; Vaccine; Plasmid; Immunogenicity; Gene therapy; Replicon
• ISSN: 0969-7128; 1476-5462
• DOI: 10.1038/gt.2008.164

Replicon plasmids encoding an alphavirus RNA replicase constitute an alternative to conventional DNA plasmids with promise for DNA vaccination in humans. Replicase activity amplifies the levels of transgene mRNA through a copying process involving double-stranded (ds) RNA intermediates, which contribute to vaccine immunogenicity by activating innate antiviral responses. Toll-like receptor 3 (TLR3) is a dsRNA innate immune receptor expressed by antigen-presenting dendritic cells (DCs). Here, we test the hypothesis that TLR3 is necessary for the immunogenicity of replicon plasmid-based DNA vaccines. We show that mouse CD8α
+
DC phagocytose dying replicon plasmid-transfected cells
in vitro
and are activated in a TLR3-dependent manner by dsRNA present within those cells. However, we find that cytotoxic T-cell responses to a replicon plasmid intramuscular vaccine are not diminished in the absence of TLR3
in vivo
. Our results underscore the potential role of TLR3 in mediating immune activation by dsRNA-bearing replicon plasmid-transfected cells and indicate that other innate sensing pathways can compensate for TLR3 absence
in vivo
.