ICP0-Mediated Recombinant Protein Expression for Viral Yield
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Solution Overview
Problem
Current methods for producing replication defective viruses, such as the HSV529 vaccine, face challenges in achieving high yields due to suboptimal expression of complementary proteins like ICP8, which are essential for viral replication, especially in cell lines like AV529-19 used for vaccine production.
Innovation Solution
Introducing the immediate early HSV protein, ICP0, into AV529-19 cells through transduction or transfection to enhance the expression of ICP8 and other recombinant proteins, thereby increasing the yield of replication defective viruses like HSV529.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If replication defective virus is produced in cell culture using complementary helper cells, then viral replication can be supported, but expression of complementary proteins is suboptimal which limits viral yield
Solution Approach 1:
The patent introduces ICP0 into the host cell before viral infection occurs, so that the protein is already expressed at high levels when the replication defective virus enters the cell. This preliminary expression of ICP0 ensures optimal conditions are in place for viral replication and protein complementation, resolving the issue of suboptimal expression limiting viral yield.
Solution Approach 2:
The patent changes the expression level parameter of ICP0 from normal/background levels to high levels by using strong promoters and optimization techniques. This parameter change in protein expression level directly addresses the suboptimal expression problem and enables high viral yield production.
2Reliability
If essential genes are removed from viral genome to prevent viral replication for vaccine production, then viral replication is blocked, but expression of complementary proteins in trans becomes necessary which is suboptimal
Solution Approach 1:
ICP0 is introduced into the host cell before viral infection, establishing optimal protein expression conditions in advance. This ensures that when the replication defective virus enters the cell, the complementary proteins are already expressed at high levels, maximizing viral yield while maintaining replication prevention.
Solution Approach 2:
ICP0 acts as an intermediary protein that mediates between the removed essential genes and the complementary proteins provided in trans. By expressing ICP0 at high levels, it facilitates optimal interaction and function of the complementary proteins, thereby maximizing viral yield despite the removed genes.
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 introduction of ICP0 significantly increases the expression of ICP8 and other recombinant proteins, leading to higher yields of replication defective viruses, improving the production efficiency of vaccines like HSV529.
Implementation Method 1
ICP0 was discovered in the late 1980s and early 1990s, but its function is still largely unknown. It has been reported that ICP0 may activate gene transcription
Implementation Method 2
At least four mechanisms have been proposed to explain how ICP0 modulates gene transcription. These generally involve the modification of chromatin in order to derepress the HSV genome after replication in neuronal cells
Implementation Method 3
A fundamental feature of ICP0 is its E3 ubiquitin ligase activity mediated by its RING domain. ICP0 causes ubiquitination of proteins, which leads to their degradation or changes in their function
Data Source
AI summary
Methods and compositions for increasing the production of recombinant proteins by introducing ICP0 to cells capable of producing a recombinant protein are encompassed. In one method, the recombinant protein is a protein that is required for the replication of a replication defective virus, wherein the recombinant protein is provided to the replication defective virus in trans.