Filtration:Vendor Notes: The Effect of Flux Decay on a 20-nm Nanofilter for Virus Retention - - BioPharm International


Filtration:Vendor Notes: The Effect of Flux Decay on a 20-nm Nanofilter for Virus Retention

BioPharm International
Volume 20, Issue 4

Three commercially available lots of Virosart CPV Minisarts were used for each nanofiltration study. Each lot was run in triplicate. Figures 1–4 display all nine data sets per protein solution filtered. For each test, protein type, protein concentration, pH, buffer type, and composition, as well as the spiking concentration, are outlined.

Figure 2
Four proteins were used for this nanofiltration study:
  • clinical grade of human-derived intra-venous immune globlulin (IVIG) at 2 mg/mL
  • monoclonal antibody at 8 mg/mL
  • sheep-derived Fab(2) at 5 mg/mL
  • bovine serum albumin (BSA) at 1 mg/mL.


Figures 1–4 show LRV over a wide flow decay using PP7 as the model virus for small non-enveloped viruses. The Virosart CPV provided reliable virus retention of small viruses.

Figure 3
The goal was >4 log10, which was achieved with little variation across the range. This shows that the capability of Virosart CPV to retain more than 4 log10 of small non-enveloped viruses is not necessarily correlated to the flux decay. Reliable retention of more than 4 log10 is shown for flux decay profiles of up to 90%.

Figure 4
The data shown are typical examples for different protein types, buffers, and concentrations. They cannot, however, be used to predict the nanofilter performance in general. Specific virus clearance studies under good laboratory practices conditions must be carried out for each biopharmaceutical product going into Phase 1 or 3 clinical trials. Finally, it is up to the end user to determine what levels of flow decay and virus retention are acceptable in order to achieve the targeted virus retention.

Upcoming studies

Upcoming studies will feature porcine parvo virus (PPV) and minute virus of mice (MVM) studies, each with co-spikes of bacteriophage PP7 to provide evidence of the capability of bacteriophage PP7 to serve as a model virus for small nonenveloped viruses. Different spike preparation scenarios will be outlined, and technologies are being screened for their capability to purify virus spikes for easier and more standardized nanofiltration spiking studies.

Klaus Tarrach is the senior product manager of purification technologies at Sartorius AG Germany in Gottingen, +49 551. 308. 3959,

Anika Meyer is an application specialist in purification technologies for Central Europe at Sartorius AG Germany;
Julia Elena Dathe is a research assistant in the Sartorius virology department; and
Hanni Sun is a biologist in the Sartorius virology department.


1. International Conference on Harmonization. Q5A. Viral safety evaluation of biotechnology products derived from cell lines of human or animal origin. Geneva, Switzerland; 1998.

2. Schmidt S, Mora, J, Dolan S, Kauling, J. An integrated concept for robust and efficient virus clearance and contaminant removal in biotech process. BioProcess Int. 2005 Sept.; 3(9):26-31.

3. Immelmann A, Kellings K, Stamm O, Tarrach K. Validation and quality procedures for virus and prion removal in biopharmaceuticals. BioProcess Int. 2005 Sept;3(9):38-44.

4. Cabatingan, M. Impact of virus stock quality on virus filter validation. BioProcess Int. 2005 July;3(7):39-43.

5. Bailey M. Normal flow virus filtration—Detection and assessment of endpoint in bioprocessing. PDA viral safety conference; 2005 May; Tampa, FL.

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