Chimeric VP1 Protein Self-Assembling Stable VLPs
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Solution Overview
Problem
Current vaccines for rabbit haemorrhagic disease (RHDV) face challenges in stability and efficacy, particularly against variant RHDVb, due to low expression levels, high costs, and complex purification procedures, as well as concerns about safety from inactivated virulent vaccines.
Innovation Solution
A chimeric VP1 protein is developed, combining the N-terminal sequence from RHDVa with the C-terminal sequence from RHDVb, which self-assembles into stable VLPs with T=3 symmetry, providing protection against RHDVb and potentially other subtypes, and is produced using a recombinant baculovirus system for enhanced stability and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If inactivated forms of the original pathogens are used for vaccination, then high effectiveness for controlling RHD is achieved, but safety concerns arise due to potential spread of the virus during viral inactivation
Solution Approach 1:
The patent extracts only the protective antigenic components (VP1 capsid protein) from the complete virus, creating VLPs that lack the viral genome. This extraction eliminates the harmful replication capability while preserving the protective immunogenic properties, resolving the contradiction between effectiveness and safety.
Solution Approach 2:
The patent creates accurate copies of the viral capsid structure (VLPs) that mimic the native virion's antigenic properties without containing functional viral genetic material. These copies provide immune protection identical to the real virus but cannot replicate or cause disease, thus resolving the safety-effectiveness contradiction.
2Object-affected harmful factors
If recombinant VP1 protein vaccines are produced, then safety concerns are addressed, but low expression levels, high costs, and complex purification procedures occur
Solution Approach 1:
The patent merges multiple copies of the VP1 coding sequence into a single operon under one promoter, enabling simultaneous high-level co-expression of all capsid proteins needed for VLP assembly. This merging strategy overcomes the low expression levels associated with individual gene expression and facilitates efficient VLP production.
Solution Approach 2:
The patent utilizes the virus's own self-assembly mechanism, where expressed VP1 proteins automatically fold and assemble into VLPs without requiring complex external assembly machinery. This self-service approach simplifies production and purification while maintaining high productivity and safety.
3Reliability
If VLPs are produced using recombinant expression systems, then safety and immunogenicity are improved, but complex purification procedures are required
Solution Approach 1:
The expressed VP1 proteins automatically self-assemble into VLPs in the host cell cytoplasm, utilizing the proteins' intrinsic ability to form supramolecular structures. This self-assembly occurs during expression itself, greatly simplifying downstream purification compared to producing soluble proteins that require complex folding and assembly protocols.
4Adaptability or versatility
If wild-type RHDVb VLPs are produced, then antigenic specificity is achieved, but stability issues occur
Solution Approach 1:
The patent modifies only specific regions of the VP1 protein sequence while preserving the overall fold and self-assembly capability. By making localized sequence adjustments to enhance stability without altering the critical antigenic epitopes, the vaccine maintains antigenic specificity for RHDVb while achieving improved compositional stability.
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 chimeric VP1 protein-based vaccine demonstrates stability and effectiveness in protecting rabbits against RHDVb and RHDVa challenges, offering a dual formulation that confers resistance to both strains, overcoming the instability issues of wild-type RHDVb VLPs and ensuring safety without the risks associated with inactivated virulent vaccines.
Implementation Method 1
These multimeric protein cages are based on the natural intrinsic ability of structural viral subunits to spontaneously self-assemble into nanoparticles (in the range of 25-100 nm)
Data Source
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Figure 3A~3C
AI summary
Virus-like particles (VLPs) have received a considerable amount of attention due to their potential application in veterinary vaccines against infectious diseases. This is the case for the rabbit haemorrhagic disease virus (RHDV), a virus which is unable to propagate in cultured cells. RHDV is the causative agent of the Rabbit Haemorrhagic Disease, one of the most economically important disease in rabbits worldwide. The RHDV capsid structure is based on a T = 3 lattice, containing 180 copies of identical VP60 subunits, similar to those of other caliciviruses. It was found that the VP1 protein of a devastating new strain, i.e. RHDVb, does not produce stable self-assembled VLPs when the capsid protein is expressed in insect cells or other systems. This application describes the generation of stable VLPs to be used as a vaccine against RHDVb. This was achieved by engineering a stable fusion protein. Collectively, this invention solves the problem of producing stable VLPs for use in vaccines against the predominant circulating strain of this virus, i.e. RHDVb.