Cation-Exchange Prefiltration to Reduce Virus Filter Fouling
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Solution Overview
Problem
Existing virus filtration methods face fouling issues due to impurities, leading to reduced filtration capacity and throughput, particularly in the removal of parvoviruses, despite advancements in membrane technology.
Innovation Solution
Implementing a prefiltration process that includes both cation exchange and endotoxin removal steps before virus filtration, using membranes with pore sizes between 15-100 nm, to address fouling and enhance filtration capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thin retentive membrane layer is used to achieve high selectivity and high throughput for parvovirus filtration, then virus retention and protein passage are improved, but the filter becomes susceptible to fouling by impurities resulting in lower filter capacity and flux
Solution Approach 1:
The patent applies preliminary action by implementing a prefiltration step using depth filters or sterile filters to remove impurities such as protein aggregates and cell debris before the feed stream enters the virus filter. This preliminary removal of foulants prevents fouling of the thin retentive membrane layer, thereby maintaining both high virus retention and high filter capacity throughout the filtration process
Solution Approach 2:
The patent segments the filtration process into two distinct stages: a prefiltration stage using depth filters with larger pore sizes to remove impurities, and a virus filtration stage using thin retentive membrane layers to retain viruses while allowing protein passage. This segmentation allows each stage to be optimized for its specific function without compromise
2Reliability
If the pore size of the virus filter is reduced to retain smaller parvoviruses, then viral retention is improved, but the filter becomes more susceptible to pore blockage and fouling
Solution Approach 1:
The patent removes potential pore-blocking impurities through prefiltration before the feed stream reaches the virus filter with small pore sizes. This preliminary action ensures that the fine pores are not blocked by larger impurities, maintaining both high viral retention and sustained filter performance
Solution Approach 2:
The patent introduces depth filters as an intermediary component between the feed stream and the virus filter. This intermediary layer captures and removes impurities that would otherwise block the pores of the virus filter, protecting the fine-pore membrane while allowing it to maintain its high viral retention capability
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
Significantly improves virus filtration capacity and throughput by effectively removing foulants, ensuring robust viral retention and maintaining filter performance.
Implementation Method 1
downstream purification processes are designed to include process steps that remove endogenous and adventitious viruses... virus removal is typically performed using chromatography and filtration
Implementation Method 2
The fouling of the virus filters has been attributed to contaminants such as protein aggregates and denatured protein
Implementation Method 3
virus filtration removes viruses by size exclusion and is therefore considered a more robust technique
Data Source
AI summary
The present invention relates to the field of protein purification. In particular, the invention concerns methods for increasing the filtration capacity of virus filters, by combined use of endotoxin removal and cation-exchange media in the prefiltration process.