Mutant IBV Spike Protein for Cell Line Production
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Solution Overview
Problem
Current IBV vaccines produced using embryonated eggs face challenges such as decreased immunogenicity upon serial passaging, genetic variability, high production costs, and risks from adventitious viruses, making them unreliable and inefficient for consistent vaccine production.
Innovation Solution
Development of an IBV spike protein with specific amino acid substitutions in the S2 domain, allowing the virus to exhibit extended tissue tropism and grow on cell lines like Vero cells, enabling consistent vaccine production without the need for embryonated eggs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If serial passaging is used to attenuate the virus for vaccine production, then the virus becomes safer, but immunogenicity decreases and genetic variability increases
Solution Approach 1:
The patent applies parameter changes by introducing specific amino acid substitutions at defined positions in the S2 domain (positions 686-694, 578, 617, 826, 857, and 1000) to achieve attenuation. This replaces the random parameter changes that occur during serial passaging with controlled, targeted modifications that maintain immunogenicity while ensuring safety and genetic consistency.
Solution Approach 2:
The patent extracts the essential attenuation function from the random serial passaging process and concentrates it into specific amino acid substitutions in the S2 domain. By isolating the critical genetic changes needed for attenuation into defined positions, the invention eliminates the need for extended passaging that causes immunogenicity loss and genetic drift.
2Productivity
If embryonated eggs are used for virus production, then vaccine can be produced, but production costs increase and supply reliability decreases
Solution Approach 1:
The patent replaces expensive, limited-supply embryonated eggs with inexpensive, easily cultured cell lines. Cell lines can be maintained indefinitely in vitro, providing a reliable, scalable, and cost-effective production system that eliminates the seasonal and logistical constraints of egg-based production.
Solution Approach 2:
The patent substitutes the biological system of embryonated eggs with a cell culture system. This replacement enables standardized, controllable, and scalable virus production through established cell culture techniques, improving both productivity and supply reliability.
3Productivity
If embryonated eggs are used as host system, then virus can be produced, but adventitious viruses may contaminate the vaccine
Solution Approach 1:
The patent replaces embryonated eggs with cell lines that can be cultured in controlled environments, eliminating the risk of adventitious virus contamination from eggs. Cell lines provide a defined, controllable host system that reduces biological variability and contamination risks.
4Stability of the object's composition
If the S2 domain sequence is highly similar to restricted tropism strain, then immunogenicity is maintained, but tissue tropism remains limited
Solution Approach 1:
The patent applies local quality by making targeted amino acid substitutions at specific positions (686-694, 578, 617, 826, 857, and 1000) in the S2 domain while maintaining high sequence identity elsewhere. This localized modification approach extends tissue tropism to include Vero cells and other mammalian cell lines while preserving the overall immunogenic properties of the original strain.
Data Source
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AI summary
The present invention provides an infectious bronchitis virus (IBV) spike protein (S protein) which is based on an S protein from an IBV strain with restricted tissue tropism, but which comprises the sequence XBBXBX in the part of the S2 protein corresponding to residues 686 to 691 of the sequence given as SEQ ID No. 2, where B is a basic residue and X is any amino acid; and which comprises at least one of the following amino acid substitutions with reference to the position numbering of SEQ ID NO:2: Leucine (L) to Phenylalanine (F) at position 578 Asparagine (N) to Serine (S) at position 617 Asparagine (N) to Serine (S) at position 826 Leucine (L) to Phenylalanine (F) at position 857 and Isoleucine (I) to Valine (V) at position 1000 such that an IBV virus comprising the S protein has extended tissue tropism. The present invention also provides a virus comprising such an S protein.