Influenza Virus Replication via 3' UTR Mutations
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Solution Overview
Problem
Current influenza vaccine production methods face challenges in achieving high viral titers in cell culture and embryonated eggs, leading to delayed vaccine production and potential shortages, especially with vaccine strains like PR8 that replicate to low titers.
Innovation Solution
Introducing specific mutations in the 3' UTR of the M gene segment, such as G1012C, A1013U, and U1014A, and potentially in the PA and PB2 gene segments, to enhance viral replication by altering microRNA binding sites, combined with optimizing internal gene segments and codon usage for higher polymerase activity and replication efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional influenza vaccine production methods are used, then production process is simple, but viral titers are low leading to delayed vaccine production
Solution Approach 1:
The patent applies parameter changes by introducing specific nucleotide mutations in the 3' UTR regions of influenza virus gene segments (M, PA, PB2 genes). These mutations alter microRNA binding sites, specifically changing the binding affinity between cellular miRNAs (such as let-7c, miR-125b, miR-150, miR-223, miR-382) and viral mRNAs. By modifying the sequence parameters at positions 1011-1017 in the M gene, 2210-2223 in the PA gene, and 2326-2331 in the PB2 gene, the invention achieves enhanced viral replication and increased viral titers in cell culture and embryonated eggs, thereby resolving the contradiction between productivity and production time.
2Productivity
If mutations are introduced to enhance viral replication, then viral titers increase, but risk of reversion increases
Solution Approach 1:
The patent applies segmentation by distributing multiple independent mutations across different gene segments (M gene, PA gene, and PB2 gene). Instead of relying on a single mutation, the invention introduces mutations at multiple positions within the 3' UTR regions of these separate gene segments. This segmentation approach ensures that viral replication enhancement is achieved through the combined effect of multiple mutations, making it highly improbable for the virus to revert to its original state, as all mutations would need to revert simultaneously. This resolves the contradiction between productivity and reliability by maintaining stable enhanced replication across passages.
3Reliability
If multiple mutations are incorporated to decrease reversion rate, then mutation stability increases, but manufacturing complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-designing and pre-introducing multiple specific mutations into the influenza virus genome during the reverse genetics construction phase. The mutations at defined positions (1011-1017 in M gene, 2210-2223 in PA gene, 2326-2331 in PB2 gene) are incorporated into the plasmid constructs before virus generation. This preliminary establishment of multiple stable mutations ensures that the enhanced replication phenotype is locked in from the beginning, eliminating the need for subsequent selection or stabilization steps. The approach resolves the contradiction between reliability and manufacturing complexity by making the multi-mutation strategy straightforward during the initial cloning process rather than requiring complex post-generation manipulation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The mutations significantly increase viral titers in Vero cells and embryonated chicken eggs, leading to more efficient and cost-effective vaccine production, addressing the issue of low titers and potential shortages by enhancing replication capabilities.
Implementation Method 1
Influenza virus replication by inhibiting microRNA lec7C binding to influenza viral cRNA and mRNA
Data Source
AI summary
A vector, composition and method to improve influenza virus replication by inhibiting miRNA lec-7C binding to influenza virus mRNA and/or cRNA.