Antibody-enhanced hepatitis E virus nanofiltration during the manufacture of human immunoglobulin

Integration of Planova filters in manufacturing processes of biologicals improve the virus safety effectively: A review of publicly available data

The capacity to remove viruses by Planova filters produced by Asahi Kasei, primarily by small virus-retentive filters, were compiled from data in peer-reviewed publications and, partly, publicly available data from presentations at conferences (Planova workshops). Data from more than 100 publications and presentations at conferences covering Planova filters were assessed. The data were grouped according to the different virus filters regarding mean pore sizes and viruses of different sizes for plasma and cell culture derived products. Planova 15N and 20N filters removed parvoviruses below the limit of detection of viruses in the filtrate in approx. 50% of all studies and mean LRFs (log reduction factors) for viruses detected in the filtrate were above 4, demonstrating effective parvovirus reduction. Parvovirus removal capacity increased for Planova BioEX filters as well as for 2 Planova 20N in series. Large viruses as retroviruses (e.g., HIV and MuLV), herpesviruses, flaviviruses and togaviruses were removed effectively by Planova 15N, 20N and BioEX filters and also by Planova 35N filters. Flow interruption, transmembrane pressure, volume and protein concentration per filter area had had no substantial impact on virus removal capacity at manufacturing specification. In conclusion, the incorporation of Planova filters in manufacturing processes of biologicals remove, depending on the filter pore size, small and large viruses from the feed stream reliably. This virus reduction step with an orthogonal mechanism integrated in the manufacturing processes of biologicals, based primarily on size exclusion of viruses, improves the virus safety of these biopharmaceutical products considerably.

Transfusion-transmitted hepatitis E: What we know so far?

Hepatitis E virus (HEV) is a major cause of viral hepatitis globally. There is growing concern about transfusion-transmitted HEV (TT-HEV) as an emerging global health problem. HEV can potentially result in chronic infection in immunocompromised patients, leading to a higher risk of liver cirrhosis and even death. Between 0.0013% and 0.281% of asymptomatic blood donors around the world have HEV viremia, and 0.27% to 60.5% have anti-HEV immunoglobulin G. HEV is infectious even at very low blood concentrations of the virus. Immunosuppressed patients who develop persistent hepatitis E infection should have their immunosuppressant regimen reduced; ribavirin may be considered as treatment. Pegylated interferon can be considered in those who are refractory or intolerant to ribavirin. Sofosbuvir, a nucleotide analog, showed modest antiviral activity in some clinical studies but sustained viral response was not achieved. Therefore, rescue treatment remains an unmet need. The need for HEV screening of all blood donations remains controversial. Universal screening has been adopted in some countries after consideration of risk and resource availability. Various pathogen reduction methods have also been proposed to reduce the risk of TT-HEV. Future studies are needed to define the incidence of transmission through transfusion, their clinical features, outcomes and prognosis.

Filter made of cuprammonium regenerated cellulose for virus removal: a mini-review

In 1989, Asahi Kasei commercialized a porous hollow fiber membrane filter (Planova™) made of cuprammonium regenerated cellulose, making it possible for the first time in the world to "remove viruses from protein solutions by membrane filtration". Planova has demonstrated its usefulness in separating proteins and viruses. Filters that remove viruses from protein solutions, i.e., virus removal filters (VFs), have become one of the critical modern technologies to assure viral safety of biological products. It has also become an indispensable technology for the future. The performance characteristics of VFs can be summarized in two points: 1) the virus removal performance increases as the virus diameter increases, and 2) the recovery rate of proteins with molecular weights greater than 10,000 exceeds the practical level. This paper outlines the emergence of VF and its essential roles in the purification process of biological products, requirements for VF, phase separation studies for cuprammonium cellulose solution, comparison between Planova and other regenerated cellulose flat membranes made from other cellulose solutions, and the development of Planova. The superior properties of Planova can be attributed to its highly interconnected three-dimensional network structure. Furthermore, future trends in the VF field, the subject of this review, are discussed.

Phenotypic characterization of cell culture-derived hepatitis E virus subjected to different chemical treatments: Application in virus removal via nanofiltration

Safety evaluation for the hepatitis E virus (HEV) is required for plasma fractionation products. Plasma-derived HEV (pHEV) is quite unique in that it is associated with a lipid membrane, which, when stripped during manufacturing processes, induces morphological changes in the virus, making it difficult to select proper HEV phenotypes for clearance studies. We developed a convenient system for the preparation of a high titer cell culture-derived HEV (cHEV). In this system, PLC/PRF/5 cells transfected with the wild-type HEV genome generated lipid membrane-associated cHEV for a long period even after cryopreservation. We also examined how this lipid membrane-associated cHEV can be used to verify the robustness of pHEV removal via 19-nm nanofiltration. Sodium-deoxycholate and trypsin (NaDOC/T) treatment not only dissolved lipid but also digested membrane-associated proteins from pHEV and cHEV, making the resulting cHEV particle smaller in size than any pHEV phenotypes generated by ethanol or solvent-detergent treatment in this study. In both 19-nm and 35-nm nanofiltration, cHEV behaved identically to pHEV. These results indicate that cHEV is a useful resource for viral clearance studies in term of availability, and the use of NaDOC/T-treated cHEV ensured robust pHEV removal capacity via 19-nm nanofiltration.

Antibody-enhanced hepatitis E virus nanofiltration during the manufacture of human immunoglobulin

BACKGROUND

Circulation of hepatitis E virus (HEV) in areas where plasma is sourced for the manufacture of plasma-derived medicinal products (PDMPs) has prompted verification of HEV clearance. HEV exists as quasi lipid-enveloped (LE) and non-lipid-enveloped (NLE) forms, which might be of relevance for HEV clearance from manufacturing processes of antibody-containing PDMPs with solvent/detergent (S/D) treatment upstream of further clearance steps.

STUDY DESIGN AND METHODS

Presence of different HEV particles in stocks used in clearance studies was investigated, with nanofilters graded around the assumed HEV particle sizes and by gradient centrifugation. HEV removal by 35-nm nanofiltration was investigated in the presence or absence of HEV antibodies, in buffer as well as in immunoglobulin (IG) manufacturing process intermediates.

RESULTS

HEV particles consistent with LE, NLE, and an "intermediate" (IM) phenotype, obtained after S/D treatment, were seen in different HEV stocks. In the absence of HEV antibodies, log reduction factors (LRFs) of 4.0 and 2.5 were obtained by 35-nm nanofiltration of LE and IM HEV, consistent with the larger and smaller sizes of these phenotypes. Addition of HEV antibodies enhanced IM HEV removal around 1000-fold (LRF, 5.6). Effective (LRF, >4.8 and >4.0) HEV removal was obtained for the nanofiltration processing step for IG intermediates with varying HEV antibody content.

CONCLUSION

HEV spikes used in clearance studies should be carefully selected, as differences in physicochemical properties might affect HEV clearance. Antibody-mediated enhancement of HEV nanofiltration was demonstrated in IG process intermediates even at low HEV antibody concentration, illustrating the robustness of this manufacturing step.