Maximizing antigen targeting to the proteasome for gene-based vaccines

Wild-type or immunoevasive antigens can drive weak CD8+T-cell responses against both dominant and subdominant epitopes during gene-based vaccination. For many antigens, fusion to ubiquitin (Ub) to target them to the proteasome circumvents this problem. Although this procedure works in most cases, fo...

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Bibliographic Details
Published in:Molecular therapy 2004-09, Vol.10 (3), p.432-446
Main Authors: Andersson, Helen A, Barry, Michael A
Format: Article
Language:English
Subjects:
Animals
Antibody Formation
Antigen Presentation
Antigens
Antigens, Viral - genetics
Antigens, Viral - immunology
Artificial Gene Fusion
CD8-Positive T-Lymphocytes - immunology
CD8-Positive T-Lymphocytes - metabolism
Cell cycle
Cell Line
Enzymes
Epitopes
Female
Gene therapy
Genetic Vectors
Green Fluorescent Proteins - biosynthesis
Green Fluorescent Proteins - genetics
Humans
Influenza
Influenza A virus - immunology
Mice
Mice, Inbred BALB C
Mutation
Nucleoproteins - genetics
Nucleoproteins - immunology
Peptides
Proteasome Endopeptidase Complex - metabolism
Proteins
Signal transduction
Ubiquitin - genetics
Ubiquitin - metabolism
Vaccines
Vaccines, DNA - immunology
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Description
Summary:Wild-type or immunoevasive antigens can drive weak CD8+T-cell responses against both dominant and subdominant epitopes during gene-based vaccination. For many antigens, fusion to ubiquitin (Ub) to target them to the proteasome circumvents this problem. Although this procedure works in most cases, for one subset of antigens, Ub fusion does not improve immune responses. To determine why these failures occur, we have evaluated in detail the 'rules' for proteasome targeting that have been applied in mammalian vaccine studies, but that were actually defined in yeast systems. To do this, we fused a series of engineered Ub genes to green fluorescent protein (GFP) and tested their ability to target GFP to the proteasome for enhanced antigen processing and CD8+ T-cell responses. Here we demonstrate that Ub fusion mediates enhanced CD8+ responses by proteasome targeting rather than by enhancing protein translation. We also show that several of the yeast-defined Ub constructs failed to target the proteasome in mammalian cells and likewise failed to enhance transgene-specific CD8+ T-cell responses in mice. In contrast, when mammalian-optimized constructs were applied to target the influenza virus nucleoprotein, CD8+ responses were enhanced against its refractory subdominant epitope in mice. This work demonstrates that Ub fusion has efficacy to enhance CD8+ responses, especially against subdominant antigen epitopes, provided constructs are optimized for mammalian use.
ISSN:1525-0016
1525-0024
DOI:10.1016/j.ymthe.2004.05.035