AAV Rep78 Sequence Deoptimization for Hybrid Virus Stability
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Solution Overview
Problem
Current methods for constructing hybrid Adenovirus/Adeno-associated virus (Ad/AAV) vectors face challenges due to the inhibitory effect of AAV Rep78 protein on Ad replication, leading to difficulties in generating stable, replicating hybrid viruses for gene therapy and vaccine applications.
Innovation Solution
Modification of the AAV Rep78 sequence by scrambling or deoptimization to remove the inhibitory signal, allowing for the production of recombinant adeno-associated virus (rAAV) vectors that can replicate and integrate site-specifically, reducing the inhibitory effect on Adenoviral replication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If AAV Rep78 protein is expressed in hybrid Ad/AAV vectors to enable site-specific integration, then integration capability is improved, but Adenoviral replication is inhibited
Solution Approach 1:
The invention extracts and removes the specific inhibitory sequence from the AAV Rep78 protein sequence. By deleting or modifying the nucleotide sequence encoding the inhibitory region while maintaining the amino acid sequence necessary for integration function, the patent separates the harmful replication-inhibiting activity from the useful integration capability, allowing Rep78 to function without blocking adenoviral replication
Solution Approach 2:
The invention changes the nucleotide sequence parameters of the AAV Rep78 gene while preserving the amino acid sequence. By using synonymous codons or modifying the DNA sequence without altering the encoded protein's functional regions, the patent maintains integration activity while eliminating the inhibitory effect on adenoviral replication, thus resolving the contradiction between integration capability and replication efficiency
2Productivity
If tightly regulated Rep expression systems are used in helper dependent Adenoviral vectors, then replication inhibition is reduced, but helper virus is required for replication
Solution Approach 1:
The invention extracts and removes the inhibitory sequence from Rep78, allowing the use of constitutive or stronger promoters without replication inhibition. This eliminates the need for complex tightly-regulated expression systems or helper viruses, simplifying the vector design while maintaining high replication efficiency
Solution Approach 2:
By removing the inhibitory sequence, the invention creates a Rep78 variant that can be used in simple, stable adenoviral vectors without requiring helper viruses or complex regulation mechanisms. The simplified vector system is more easily manufactured and does not require additional viral components, reducing overall system complexity
3Reliability
If first generation Adenovirus carrying AAV Rep78 is constructed, then site-specific integration is enabled, but viral stability is poor with frequent deletions
Solution Approach 1:
The invention extracts and removes the inhibitory sequence from AAV Rep78 that causes genomic instability. By eliminating this specific sequence element, the patent prevents the deletions and mutations that occur in first-generation adenoviruses carrying wild-type Rep78, thereby stabilizing the viral genome while preserving integration function
Solution Approach 2:
The invention modifies the nucleotide sequence parameters of the Rep78 coding region to remove instability-causing elements. By changing the DNA sequence while maintaining the essential amino acid sequence for integration, the patent creates a stable viral construct that maintains integration capability without suffering from frequent deletions or mutations
Data Source
AI summary
The invention provides adeno-associated virus (AAV) replication (Rep) sequences. In one embodiment, the invention provides nucleotide sequences encoding a chimeric protein, wherein the encoded chimeric protein contains a wild type AAV Rep inhibitory amino acid sequence, and wherein the nucleotide sequences contain a scrambled and/or deoptimized polynucleotide sequence encoding the wild type AAV Rep inhibitory amino acid sequence. The invention provides vectors, cells, and viruses containing the invention's sequences. Also provided are methods for detecting portions of the AAV Rep inhibitory amino acid sequence, which reduce replication and/or infection and/or productive infection by viruses. The invention's compositions and methods are useful for site-specific integration and/or expression of heterologous sequences by recombinant adeno-associated virus (rAAV) vectors and by rAAV virus particles, such as hybrid viruses (e.g., Ad-AAV) comprising such vectors. The invention's compositions and methods find application in, for example, gene therapy and/or vaccines.