Poxviral Vector Promoter Design for CD8 T Cell Response
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Solution Overview
Problem
The induction of a strong humoral and cellular immune response against foreign antigens expressed by recombinant vaccinia virus vectors is hindered by immunodominance of vector CD8 T cell epitopes, leading to competition with the vector's own antigens, and the choice of poxviral promoters affects the strength and quality of the immune response, with early expression being crucial for efficient CD8 T cell responses.
Innovation Solution
A recombinant poxviral vector using a transcriptional control element with a late promoter linked to at least two early promoter elements, which drives early expression of antigens, resulting in superior acute and memory CD8 T-cell responses while minimizing antibody production, suitable for conditions like dengue hemorrhagic fever where antibody-dependent enhancement is a concern.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a strong poxviral promoter is used to drive high expression of foreign antigens, then the amount of antigen expressed is increased, but the antibody response after first priming immunization becomes excessively high
Solution Approach 1:
The promoter is designed to drive antigen expression in a temporally regulated manner, with high expression during the early phase of viral infection (first 2-4 hours) when antigen presentation to T cells is most effective, and reduced expression during the late phase when antibody production would be excessive. This periodic action pattern matches the immune response timeline to achieve optimal immunogenicity without excessive antibody production
2Reliability
If early promoter elements are used to drive antigen expression, then CD8 T cell response is enhanced, but the expression level during late phase is insufficient
Solution Approach 1:
The promoter construct merges multiple early promoter elements (specifically five copies of the immediate early promoter p7.5) to create a composite promoter that drives extremely high levels of antigen expression during the early phase of infection. This merging of multiple promoter elements amplifies the early expression signal to ensure sufficient antigen is presented to CD8 T cells during the critical early window of immune response initiation
3Reliability
If the number of early promoter elements is increased to enhance early expression, then CD8 T cell response is improved, but the promoter size and complexity increase
Solution Approach 1:
The promoter is constructed by segmenting and replicating a functional unit - specifically, five identical copies of the immediate early promoter p7.5 are arranged in tandem. This segmentation approach allows each copy to function independently but collectively they produce synergistic high-level early expression. The modular repetitive structure simplifies the design process compared to creating a completely novel complex promoter sequence
Data Source
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AI summary
The invention is drawn to compositions and methods for the induction of an immune response, in particular a strong CD8 T cell response, to a specific antigenic determinant without raising a significant antibody response to the antigenic determinant after a first, priming immunization. The method comprises administering to the host a recombinant poxviral vector comprising a transcriptional control element comprising an early and/or late element linked to a nucleotide sequence encoding the antigenic determinant. The recombinant poxviral vector comprises a transcriptional control element comprising an early and/or late element linked to a nucleotide sequence encoding the antigenic determinant. The late element may be stronger than the cowpox ATI promoter in HeLa cells.