Virus Filtration Using a High-Throughput Parvovirus-Retentive Membrane - The authors describe testing and validation processes for Virosart HF, a surface modified polyethersulfone hollow-fiber parvovi

ADVERTISEMENT

Virus Filtration Using a High-Throughput Parvovirus-Retentive Membrane
The authors describe testing and validation processes for Virosart HF, a surface modified polyethersulfone hollow-fiber parvovirus filter.


BioPharm International Supplements
pp. s34-s38


Figure 1a: Hollow fiber cross section. (All figures courtesy of the authors.)
Filter Design and Validation
To overcome current limitations in virus filtration—and as a step toward the development of common standards—a high-performance, hollow-fiber parvovirus filter has been developed, which demonstrates robust retention at high transmembrane pressures. The unique structure of the membrane and its chemically modified surface address many of the limitations of current retentive filters.


Figure 1b: Comparison of a 0.8/2.4-m process module and a 5-cm laboratory module with vent filter for contained flushing.
The Virosart HF filter (Sartorius-Stedim) features a surface-modified asymmetric polyethersulfone (PES) hollow-fiber membrane optimized for the manufacture of monoclonal antibodies (see Figure 1a). The membrane is characterized by a funnel-like pore size gradient designed to achieve the robust retention of parvoviruses under challenging conditions (such as high blockage or pressure release) without impeding the efficient transfer of high-molecular-weight proteins such as monoclonal antibodies. The membrane is surface-modified with a hydrogel-forming, low-binding polymer, to reduce the adsorption of soluble proteins and protein aggregates. The pore size gradient and the hydrogel are unique aspects of the membrane that contribute to its high performance. The hollow fibers can be packed densely into modules ranging in capacity from 5 cm to 2.4 m, the latter presented as a presterilized 10-in single-use device (see Figure 1b). The capacity of the filter can be extended by combining it with the Virosart MAX adsorptive pre-filter, featuring an optimized polyamide microfiltration flat-sheet membrane in a homogeneous triple-layer configuration, with a nominal pore size of 0.1 m.


Figure 2: Water flow rate in Virosart HF capsules taken from three individual lots of the 2.4-m module. Each capsule lot was built from a different membrane lot. The average permeability is 170 liter/mh bar.
Validation of Virosart HF has proven the consistent performance of the product family. Figure 2 shows selected validation data (permeability of 2.4-m process modules) for illustration. However, measures have been taken to ensure future product quality from lot-to-lot. Validated in-process as well as release tests are performed during the manufacture and release of Virosart HF membranes and modules according to pre-defined sampling plans to measure and monitor critical performance attributes of all product components.

Membrane testing includes in-process and lot release tests. Membrane performance release tests are executed on laboratory modules that have experienced the same manufacturing steps as laboratory or process modules that would be shipped to customers. Virosart HF modules are in-house integrity tested by air-diffusion as well as gamma irradiated. Three membrane release tests—bacteriophage PP7 retention in buffer, bacteriophage PP7 retention in human IgG (grab sample at 75% flux decay), and water permeability—are consequently performed on lab modules, which have also been flushed with water, dried, and then exposed to gamma irradiation. Protein filtration capacity is monitored while PP7 retention in buffered human IgG solution is determined. These release tests ensure that membrane performance items meet expected and validated levels.

In addition, Virosart HF modules are released based on a 100% inspection scheme. Water flow rate and integrity of each module is tested prior to shipment. Integrity testing is based on an air-diffusion test at 4.5 bar and modules subsequently released based on a correlation between diffusive flow rate and PP7 retention.


Figure 3: The performance of the Virosart HF module family was tested for scalability using the same batch of a buffered human lgG model protein stream (highly blocking) until 95% flux decay was achieved.
The performance of the Virosart HF module family was tested for scalability using the same batch of a buffered human IgG at 2 g/L. Three different 5-cm laboratory modules and one 0.8-m process module were challenged at 2 bar differential pressure until 95% flux decay was achieved (see Figure 3). The volume vs. time filtration data for the three laboratory modules was averaged and compared to the corresponding data for the process module according to the filtered protein mass per filtration area. Figure 3 confirms that (based on the performance data gathered using 5-cm devices) laboratory modules can be scaled-up to larger feed stream volumes and filter areas.


Figure 4: Virosart HF laboratory modules were challenged with a 10-20-g/L monoclonal antibody solution (pH 6-7, conductivity 4-8 mS/cm) spiked with 0.5% MMV. Experiments were carried out at constant flux at 120 L/m2h. The membrane was challenged with up to 7.4-kg antibody/m2 resulting in a permeability decay of more than 70%. A log reduction value of greater than 5 was achieved in both spike trials (Run B and Run C).
The retentive capabilities of the Virosart HF filter were tested under worst-case conditions, by challenging with a 10-20-g/L monoclonal antibody solution (pH 6-7, conductivity 4-8 mS/cm) spiked with 0.5% MMV. Experiments were carried out at constant flux at 120 L/mh. To implement worst-case load conditions, the membrane was challenged with more than 5.5-kg antibody/m resulting in a permeability decay of more than 70%. Two spike trials and one control trial were conducted for comparison.

In all three trials, the transmembrane pressure increased over time but the pressure profiles varied slightly from run to run with the mass throughput ranging from 5.8 to 7.4 kg/m (see Figure 4). The transmembrane pressure did not increase above 2.7 bar in any of the trials and thus remained below operating pressure. Breakthrough was observed in one of the spike trials but the other achieved complete retention. The log reduction values for the pooled permeate were 5.19 and 5.21, respectively (see Table I).


Table I: Summary of the filtration and MMV retention data for the control trial (Run A) and the two spike trials (Run B and Run C).
These data show that Virosart HF achieves robust log reduction values of greater than 5 even under challenging conditions, thus meeting the retentive requirements of a high-performance parvovirus filter with minimal lot-to-lot variability.


blog comments powered by Disqus

ADVERTISEMENT

ADVERTISEMENT

Novartis Reports Positive Results for Secukinumab in Ankylosing Spondylitis Trials
October 23, 2014
Pall ForteBio Releases Bioprocessing Contamination Detection Kit
October 22, 2014
Roche to Expand and Improve its Basel Site
October 22, 2014
FDA Panel Unanimously Backs Secukinumab for the Treatment of Psoriasis
October 22, 2014
EMA Works to Speed Up Ebola Treatment
October 20, 2014
Author Guidelines
Source: BioPharm International Supplements,
Click here