As to antibody purification using filtration see “antibody purification”

Typical components which pass through and are retained by membranes (WO 2005/091801)

Cell culture supernatant generally has an ionic strenght between 100 and 150 mM, pH 7.5 and is likely to contain anionic or hydrophobic species other than DNA such as RNA, host cell protein and surfactants (Charlton, Bioseparation, 8, 1999, 281-291). 

DNA: 

The structure of DNA is such that electrostatic interactions are possible along the polyphosphate backbone of the molecule and hydrophobic interactions are possible within the grooves of the helix. Such a combination of both electrostatic and hydrophobic interactions for absorption of DNA using various depth filters are reported by (Charlton, Bioseparation, 8, 1999, 281-291). 

Plasma Proteins:

Fibrinogen/fibronencting, coagulation factor V, coagulation factor VII, von Willebrand Factor: 

Fibrinogen is a 340 kDa hexameric glyoprotein. It is a large protein and thus far been regarded as being too big to be freed from viruses by filtering them through a nonfilter having a pore size of from 15-35 nm. Thus far fitration methods fo fibringone have been described for a filter pore size of 35 nm. A problem here is that at a pore size of 35 nm, relatively small, noenveloped virsues such as hepatits A and parvovirus cannot be removed. However, Lengsfeld (US 2003/0232969) discloses separating off viruses from a protein solution by nanofiltration by adding a chaotropic substances such as arginine, guanidine, cirtulline, urea and derivatives thereof using filters with a pore size ranging from 15-25 nm.

Ristol Debart (EP 1,457,497) discloses remvoing viruses in fibrinogen solutions by freezing an adjusted purified solution (a cryoprecipitate, the first fraction of Cohn method or equivalent fibrinogen containing fraction is precipitated preferably with glycine) and then thawing at a temperature between 5-20C. The undissolved materials associated with the fibrinogen are subsequently separated, the temperature is adjusted and the resultant solution is finally subjected to nanofiltration using filters smaller than 35 nm. The freezing, thawing and anofiltration are carried out in the presence of at least one amino acid.  With the controlled freezing and thawing, insoluble, aggregated or partially denatured materia is precipitated that would, in pracvtice, prevent the filtration of the solution through pore sizes smaller than 35 nm. Separation of the precipitated material allows nanofiltration to a pore size smaller than 35 nm.   

Takahashi (US6,867,285) also discloses that contaminant viruses can be efficiently removed by subjected a plama protein such as fibrinogen, fibronectin, coagulation factor V, coagulation factor VII, von Willebrand Factor, coagulation factor XIII, retinol binding protein, alpha-globulin, beta-globulin and gamma-globulin to a porous membrane having a pore size greater than a single particle size of the virus which permits passage of the virus. During filtration through a porous membrane, chaotrropic amiono acid may be added. This allows enhanced expression of the effect that contaminant viruses can be removed efficiently by the porous membrane treatment without losing the activity of the protein.  

–Dual/successive filters (larger pores to smaller pores): 

Burton (US 8,198.407) disclsoes affinity capture of von Wiilbrand Factor/Factor VIII on an affinity adsorbent developed for the capture of vWF/FVIII Filtered plasma was applied on the column and the flow-through effluent was collected when the adsorbance at 280 nm reached 5%. The column was washed with  to collect the column effluent until adsrobance dropped won to 5% of the adsorbance full scale. The solution was mixed and then filtered through a 3/0.8 um SartoCelanCA followed by a 0.45/0.22 um Sartobran P filter. 

Viruses:

Viruses to be used in validation studies for plasma products should include HIV-1 , a model for HPC (e.g., Sindbis or bovine viral diarrhoea virus (BVDV); non-enveloped viruses (animal parvovirus, hepatitie A) and an enveloped DNA virus (e.g., a herpesvirus). (Brandwein, “membrane filtration for virus removal” Dev Biol. 1999, 102, pp. 157-163).  

Hepatitis E Virus (HEV): The sensitivity of HEV to heat has been shown to vary greatly depending on the heating conditions whereas HEV particles were completely removed using 20-nm nanofilters (unoki, “extent of hepatitis E virus elimination is affected by stabilizers present in plasma products and pore size of nanofilters” Vox Sanguinis 2008, 95, 94-100).

Murine Leukaemia Virus: Hazel Aranha-Creado (Biological (1998 26, 167-172) report using a hydrophilic polyvinylidenefluoride (PVDF) microporus membrane (Ultipor VF grad DV50 virus removal filter) was effective to remove endogenous retrovius like contaminants such as MLV from monoclonal IgG rpoducts.  

 Porcine parvovirus (PPV): Hongo-Hirasaki (J. Membrane Science 278 (2006) 3-9) discloses using Planova20N was effective in the removal of small viruses such as parvovius from IgG solution. Shile proteins such as IgG pass through the capillary void pore structure, viruses are exlcuded from passing through the capillary ports. Thus even in the case wehre the size of filter object (i.e., parvovirus) is very close to that of IgG, Flanova 20N shows high virus removaility less than 1/10 rejection of the original solution without damaing the IgG permeability).  For purification of viruses from antibody, see “antibody purification”.

Other Components:

Outer Membrane Vescies (OMV) from bacteria:

Olivieri (US 2007/0087017) discloses ultrafiltration for preparing bacterial OMVs. The process incldues post-ultrafiltraiton steps where the OMVs may be sterilised by passing the OMVs thorugh a standard 0.22 um filters. Because these filters can become clogged it is rpeferred to perfrom sequential steps through a series of filters of decreasing pore size, finishing with a standard sterilistation 0.22 um filter. Examples of preceeding filters include those with a pore size of 0.8 and 0.45 um.