Modified RSV F Protein Segmentation for Low-Toxicity Vaccine Expression
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Solution Overview
Problem
Current RSV vaccines face challenges in achieving high expression levels of the fusion (F) protein, which is crucial for immune response, while also causing cellular toxicity and having suboptimal immunogenicity.
Innovation Solution
Modified RSV F proteins with specific amino acid modifications, such as replacing P102 with alanine, I379 with valine, and M447 with valine, and optimizing codon sequences for enhanced expression in host cells, result in reduced toxicity and improved immunogenicity, promoting the 'lollipop' post-fusion morphology.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If full-length F protein is used to elicit immune response, then immunogenicity is improved, but cellular toxicity increases
Solution Approach 1:
The F protein is divided into two separate polypeptide chains: F1 (residues 1-382) and F2 (residues 383-574). The F1 chain contains the immunogenic fusion peptide and heptad repeat regions, while the F2 chain contains the transmembrane anchor and cytoplasmic tail. This segmentation allows the immunogenic F1 to be expressed without the toxic effects associated with full-length F protein, while still eliciting protective immune responses.
Solution Approach 2:
The F1 polypeptide chain (residues 1-382) is extracted and expressed separately from the full-length F protein. This extracted F1 fragment contains the essential immunogenic regions (fusion peptide and heptad repeats) but lacks the transmembrane and cytoplasmic domains that cause cellular toxicity when expressed in vaccine production systems.
2Productivity
If F protein expression level is increased to improve vaccine efficacy, then immunogenicity is improved, but cellular toxicity increases
Solution Approach 1:
By segmenting the F protein into F1 and F2 chains and expressing only F1 in vaccine production, the system achieves high expression levels of the immunogenic fragment without the toxicity associated with full-length F protein expression. The F1 fragment can be produced at high titers in mammalian cell cultures without causing cellular damage.
3Ease of manufacture
If F0 precursor form is used, then production simplicity is improved, but immunogenicity is reduced due to micelle formation
Solution Approach 1:
The F1 polypeptide chain is extracted and expressed separately, preventing micelle formation that occurs with full-length F0 precursor. The soluble F1 fragment expresses as monomers or small oligomers that are readily purified and formulated into stable vaccine compositions without the aggregation problems of micellar F0 protein.
Data Source
AI summary
The present invention is generally related to modified or mutated respiratory syncytial virus fusion (F) proteins and methods for making and using them, including immunogenic compositions such as vaccines for the treatment and/or prevention of RSV infection.