eShop
Sign in
English
In biopharmaceutical purification platforms, virus filtration, based on its size-exclusion mechanism, is considered one of the most effective and robust steps for viral clearance.
According to ICH Q5A(R2): Viral Safety Evaluation of Biotechnology Products Derived from Cell Lines of Human or Animal Origin, the primary mechanism of virus filtration is the removal of viruses through size exclusion, representing a separation method based on molecular size. In general, the volumetric flux of the product intermediate, as well as the flux and pressure of the buffer used to flush the filter (including pressure/flow interruptions), are potential critical parameters in virus filtration. Virus removal filtration operates based on a size-exclusion mechanism. In theory, smaller viruses have a higher risk of passing through virus filters than larger viruses. Therefore, the retention of small viruses (18–24 nm) is typically evaluated as the worst-case condition for virus retention.
This article aims to present the virus retention performance of Cobetter Viruclear™ VF series PES filters under high pressure, low pressure, normal filtration pressure, and interruption/pause conditions. It evaluates the robustness of virus retention of Cobetter virus filters and provides recommendations for filtration parameter settings during process development and virus clearance challenge studies for biopharmaceutical customers using Cobetter virus filters, as well as guidance for virus removal validation.
Case Study 1:
Using Cobetter VF Plus PES syringe filter (catalog number: VFPESDCN1P) to evaluate the removal performance of MVM under high-pressure and low-pressure filtration conditions. In addition, pressure interruption was introduced as a worst-case condition.
Two antibody feed solutions were tested: 12 g/L mAb1 solution and 1 g/L mAb2 solution. The upstream spike level of MVM was 7.2 log PFU.
The MVM titers in the feed and filtrate were determined using a Plaque Assay, and the viral removal efficiency was expressed as the Log Reduction Value (LRV).
Note: The experiment was conducted at pressures of 10 psi, 30 psi, and 60 psi. The target filtration load was 1,500 L/m² for all conditions. Upon reaching the endpoint, the pressure was released to 0 psi, followed by a 30-minute process pause, after which the pressure was restored to the previous level. A 20 L/m² buffer flush was then performed.
Experimental Conclusion:
The LRV results determined by plaque assay showed that under low pressure, recommended pressure, and high pressure conditions, the MVM levels were reduced below the quantitation limit, demonstrating the robust viral removal performance of the filter under all three pressure conditions and during process pauses.
Case Study 2:
Using Cobetter VF Plus syringe filter (catalog number: VFPMPDSN1P) to study the removal of MVM under high- and low-pressure conditions.
The feed solution was tested: a 10 g/L mAb3 solution, with a total upstream spike of MVM at 7.2 log PFU.
The MVM titers in the feed and filtrate were measured using the plaque assay, and the virus removal log reduction value (LRV) was calculated.
Note: The experiment was conducted at pressures of 10 psi, 30 psi, and 60 psi. The target filtration load was 100 mL for all conditions. In all three experimental groups, after filtration was completed, the filters were flushed with buffer at 60 L/m² (15 mL) and 200 L/m² (50 mL).
Experimental Conclusion:
The LRV results determined by the plaque assay showed that under low pressure, recommended pressure, and high pressure, as well as with a higher flush volume, the detected values were reduced to below the limit of quantification. This demonstrates the robust virus removal capability of the filter under all three pressure conditions and higher flush volumes.
In summary
Under different pressure conditions, Cobetter Viruclear™ VF series virus filters demonstrate robust retention capability for parvoviruses. Virus clearance validation studies are scale-down models that simulate the operational parameters of actual large-scale manufacturing processes, with the focus on evaluating the virus removal performance of the filter under real production parameters.
Considering the core principles of relevant domestic and international regulations or guidance documents—namely, verifying the virus clearance capability of the actual manufacturing process—we recommend the following:
1. The production process standard operating procedure (SOP) should define a stable and controllable operating pressure range for the manufacturing process.
2. A scale-down model that is representative of the actual manufacturing process should be established.
3. For virus clearance (VC) validation, it is generally recommended to use the controlled operating pressure used in actual production. When designing the VC validation study, the filtration pressure should be set to the upper pressure limit defined in the SOP, and at least one pressure interruption (reduced to 0 psi) should be introduced and maintained for a certain period to evaluate the impact of extreme low-pressure conditions. Typically, the interruption is performed at least once before the buffer flush, when the protein load and viral load are at their maximum, representing a combined worst-case scenario. Successful validation under this condition can also provide additional operational flexibility for handling unexpected situations during manufacturing.
4. If conditions permit, it is recommended to conduct an additional study evaluating the virus retention capability for MVM under the lower pressure limit specified in the SOP.
