Ad55 Replication-Defective Adenovirus Vector for Vaccine Development
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Solution Overview
Problem
Current adenovirus vaccines are ineffective against highly pathogenic types 55 and 14, and traditional adenovirus vectors face challenges due to pre-existing immune responses and safety concerns, particularly in populations with high seropositive rates for Ad2 and Ad5 neutralizing antibodies.
Innovation Solution
A human type 55 replication defective adenovirus vector is developed by knocking out the E1 and E3 genes and substituting specific E4 gene regions with corresponding Ad5 genome sequences, allowing for the integration of an exogenous gene expression cassette, which can be produced in helper cell lines like 293 and PerC6 and purified for use as vaccines or gene therapy vectors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wild type Ad4 and Ad7 are used to prepare vaccine, then the outbreaks of adenovirus epidemic in US troops can be prevented, but the vaccine has no preventive effects on Ad14 and Ad55 which are highly pathogenic, and may bring safety concerns due to residual live viruses
Solution Approach 1:
The patent changes the serotype parameter of the adenovirus from traditional Ad4/Ad7 to Ad55, and modifies the genome by deleting E1 and E3 genes to create a replication-defective vector. This parameter change enables the vaccine to protect against Ad55 specifically while eliminating the safety concerns of live virus propagation
Solution Approach 2:
The patent segments the adenovirus genome by deleting specific functional regions (E1 and E3 genes) while preserving other regions. This segmentation creates a replication-defective virus that can be used safely as a vaccine vector, separating the protective antigen function from the replication function
2Reliability
If E1 and E3 genes are deleted to create replication defective adenovirus, then safety is enhanced and protective capacity against Ad55 is improved, but the virus becomes difficult to propagate in cell lines because Ad5 E1B 55K cannot interact with E4 Orf6 from species B adenovirus
Solution Approach 1:
The patent merges the Ad55 viral backbone with the Ad5 E1B 55K gene. This combination allows the replication-defective Ad55 vector to utilize the Ad5 E1B 55K protein to interact with E4 Orf6, enabling successful propagation in cell lines like 293 and PerC6 while maintaining safety through E1/E3 deletion
Solution Approach 2:
The Ad5 E1B 55K gene acts as an intermediary that bridges the compatibility gap between Ad55 and Ad5 cellular interaction mechanisms. This intermediary element enables the replication-defective Ad55 vector to be propagated in standard cell lines by facilitating the necessary protein-protein interactions
3Reliability
If traditional adenovirus vector (Ad5 or Ad2) is used for gene therapy, then good safety and effectiveness of gene transduction are achieved, but pre-existing anti-Ad immune response limits the use due to high seropositive rate in many populations
Solution Approach 1:
The patent changes the serotype parameter from Ad5/Ad2 to Ad55, which has lower pre-existing immunity in the general population. This parameter change expands the applicable population range while maintaining effective gene transduction capabilities
Solution Approach 2:
Instead of trying to overcome pre-existing immunity against Ad5/Ad2 through various techniques, the patent inverts the approach by selecting a different serotype (Ad55) that naturally has lower pre-existing immunity. This reversal strategy simplifies the solution and expands applicability
Data Source
AI summary
Provided are a human type 55 replication defective adenovirus vector, a method for preparing the same and uses thereof. The human type 55 replication defective adenovirus vector is prepared by the following method: knocking out E1 and E3 genes from Ad55, substituting the open reading frame 6 or the open reading frames 2, 3, 4, 6, and 6/7 of E4 gene in Ad55 genome with the corresponding open reading frames of Ad5 genome. In addition, an exogenous gene expression cassette may also be integrated into the E1 gene region of Ad55.