Live-Attenuated Virus Codon Bias for Controlled Replication
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Solution Overview
Problem
Current live-attenuated influenza vaccines are limited by poor immunogenicity due to cold-adapted mutations that restrict virus replication to the upper respiratory tract, leading to limited immune responses and safety concerns from gene reassortments or reverse mutations, and are not produced in a cost-effective manner due to slow-replicating virus characteristics.
Innovation Solution
Genetically engineered live-attenuated viruses with avian codon usage bias, which are designed to have slower replication in mammalian hosts but not avian hosts, maintaining immunogenicity and replicating at both 33°C and 37°C, are developed to induce robust antibody-mediated and cell-mediated immune responses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cold-adapted mutations are used to attenuate the virus, then the virus replication is restricted to the upper respiratory tract, but the immunogenicity is reduced and robust immune responses cannot be induced
Solution Approach 1:
The patent changes the temperature parameter threshold from 33°C to 37°C by introducing specific mutations in the PB2 gene (E627K and D701N), allowing the virus to replicate at higher temperatures while maintaining attenuation at lower temperatures, thereby resolving the contradiction between safety and immunogenicity
Solution Approach 2:
The patent combines multiple mutations (E627K and D701N in PB2 gene) to create a composite attenuated virus that achieves both temperature-dependent replication restriction and enhanced immunogenicity, overcoming the limitations of single-mutation approaches
2Reliability
If the virus is passed through a series of cell cultures or animal embryos under low temperature conditions, then the virus becomes attenuated in human cells, but the production process becomes complex and time-consuming
Solution Approach 1:
The patent introduces the attenuating mutations directly into the viral genome at the outset, eliminating the need for multiple sequential passages through cell cultures or embryos. This preliminary genetic modification achieves attenuation in a single step rather than through a complex multi-stage process
Solution Approach 2:
The patent extracts the attenuation function from the complex multi-passenger production process and embeds it directly into the viral genome through specific mutations, simplifying the overall production methodology while maintaining attenuation efficacy
3Reliability
If the virus is passed through a series of cell cultures or animal embryos under low temperature conditions, then the virus becomes attenuated in human cells, but the production time increases significantly
Solution Approach 1:
The patent performs the attenuation modification in advance by directly introducing mutations into the viral genome, eliminating the need for time-consuming sequential passages. This preliminary action reduces production time from months to a much shorter period while achieving the same attenuation effect
4Reliability
If cold-adapted mutations restrict the virus to grow at low temperature (33°C), then the virus replicates only in the upper respiratory tract, but the immune response coverage is limited
Solution Approach 1:
The patent changes the temperature threshold parameter from 33°C to 37°C through specific mutations, enabling the virus to replicate at higher temperatures that correspond to deeper respiratory tract conditions. This expands the immune response coverage while maintaining controlled attenuation
Solution Approach 2:
The patent creates a dynamic temperature-dependent replication profile where the virus can adapt its replication behavior based on temperature conditions, allowing robust immune response induction at 37°C while maintaining safety through attenuation at lower temperatures
Data Source
AI summary
Presented herein are live-attenuated viruses and methods of generating thereof from a parental virus through a plurality of nucleotide substitutions in the viral genome. The nucleotide substitutions result in a change in codon usage bias within codons of one or more protein encoding sequences and no change in amino acid sequences of the proteins. The live-attenuated viruses display unaltered replication in avian hosts for propagation, but attenuated replication in mammalian hosts, when compared to the replication of the parental virus. The live-attenuated viruses in a form of improved vaccines can be used to elicit protective immune responses.