Analysis of human plasma products: polymerase chain reaction does not discriminate between live and inactivated viruses.

Background: The viral safety of human plasma products is based on the careful selection of donors and donations and the removal and inactivation of human pathogenic viruses that could potentially contaminate human plasma. For the analysis of the final products for potential virus contamination, the use of polymerase chain reaction (PCR) has been proposed. To test whether this method can discriminate between infectious and inactivated viruses, the following studies were performed.

[Nanofiltration in production of Beriplex P/N: increasing the capacity of virus elimination while maintaining product quality].

For the manufacture of the PCC Beriplex P/N, nanofiltration was introduced into the production process of Beriplex HS providing an additional means to heat treatment for the clearance/inactivation of viruses. By nanofiltration, large enveloped viruses (HSV-1, HIV-1) were completely eliminated by a factor of more than 7 log10. While medium-sized enveloped viruses (HBV, BVDV) were cleared by a factor of approximately 4 log10, small non-enveloped viruses (poliovirus) were not removed.

[HIV safety of commercially produced human plasma proteins].

An important aim of the commercial manufacturing of human plasma proteins to be used as therapeutics is the HIV-safety of such products. This aim will be achieved by using (1) plasma donations of carefully selected, healthy donors, (2) by testing of each donation according to national and international requirements for antibodies or antigens specific for certain viruses, (3) by eliminating viruses by different purification procedures of the manufacturing process and (4) by inactivating viruses by a specific method included in the production process. Due to the current discussion in Germany this paper will particularly focus on HIV.

Inactivation of hepatitis A virus by pasteurization and elimination of picornaviruses during manufacture of factor VIII concentrate.

Hepatitis A virus (HAV) infections have been reported among hemophiliacs who received factor VIII concentrates which had been purified by ion-exchange chromatography and treated by the solvent detergent (SD) method. Since the virus inactivation procedure of our manufacturing process is heat treatment of the stabilized, aqueous protein solution at 60 degrees C for 10 h (pasteurization), we investigated whether this method inactivated picornaviruses such as HAV and poliovirus type 1, which we routinely use as a test virus for non-enveloped viruses. HAV was substantially inactivated by pasteurization but the stabilizers used in the manufacturing process of the commercial products considerably delayed HAV inactivation.

Inactivation of hepatitis A virus by heat treatment in aqueous solution.

Hepatitis A virus infections have been reported recently among hemophilic patients in Italy and Germany, leading to speculation that infectious hepatitis A virus (HAV) might have been present in some factor VIII concentrates. In both cases, the implicated factor concentrates had been treated by a solvent/detergent method, which inactivates enveloped viruses but which would not be expected to inactivate HAV, a nonenveloped picornavirus. To determine whether HAV would be inactivated during pasteurization of factor VIII concentrate, an alternative method employed for virus inactivation, we determined the extent to which the infectivity of cell culture-adapted HAV, suspended either in cell culture medium or in a proprietary stabilizing buffer, was reduced by heat treatment at 60 degrees C for 10 hr.

Antiviral effects of different CD4-immunoglobulin constructs against HIV-1 and SIV: immunological characterization, pharmacokinetic data and in vivo experiments.

The CD4 cell surface antigen belongs to the immunoglobulin superfamily and is the primary receptor for the human immunodeficiency virus 1 (HIV-1). The high affinity interaction between HIV-1 and CD4 is mediated by the viral envelope glycoprotein gp120. Recombinant soluble CD4 (rsCD4) has been shown in vitro to be an effective inhibitor of HIV-1 and HIV-2 propagation in lymphoid cells.

Immune response of chimpanzees after immunization with the inactivated whole immunodeficiency virus (HIV-1), three different adjuvants and challenge.

Purified whole virus preparations of HIV-1 were produced from supernatants of infected cells and concentrated 5000-fold. After inactivation with formaldehyde, the concentrates were combined with one of three different adjuvants, and used to immunize three groups of three chimpanzees each. The chimpanzees were monitored for HIV-specific humoral and cellular immune responses by ELISA, immunoblot, virus neutralization, delayed-type hypersensitivity, lymphocyte proliferation and antibody-dependent cell-mediated cytotoxicity.

Inactivation of HIV, HBV, HCV related viruses and other viruses in human plasma derivatives by pasteurisation.

Laboratory studies were made to verify the capacity and efficacy of the pasteurisation step (heat treatment at 60 degrees C for 10 hours in stabilized aqueous solution) in inactivating various pathogenic viruses (e.g. HIV, HBV, HCV related viruses, HAV, HSV, poliovirus).

Theoretical and technical concerns in inactivation/elimination of viruses in plasma derivatives.

To know the virus eliminating/inactivating capacity of the manufacturing process of a plasma protein, it is essential to analyse it by adding virus to the source material or to different materials obtained at various stages of the manufacturing procedure and then to determine the elimination/inactivation of this virus. To carry out such experiments properly, three prerequisites have to be fulfilled: (i) the manufacturing procedure must be scaled down as exactly as possible; (ii) relevant test viruses have to be selected for the spiking experiments and (iii) the resulting samples must be assayed properly for infectious virus. The successful reduction of a manufacturing procedure to a more than 1000-fold smaller scale has to be validated to prove that it corresponds to the production scale.

Follow-up of hepatitis C virus infection in chimpanzees: determination of viraemia and specific humoral immune response.

Chimpanzees were inoculated intravenously with the H strain of hepatitis C virus (HCV), and analysed for viraemia using the polymerase chain reaction and for a humoral immune response using first and second generation anti-HCV ELISAs and an immunoblot assay (4-RIBA). In all seven chimpanzees studied, viraemia occurred several weeks before a significant increase in serum alanine transferase (ALT) activity, whereas the first circulating anti-HCV antibodies became detectable at the time of significant increase in ALT levels, provided the second generation ELISA or 4-RIBA was used. On the basis of the duration of viraemia the chimpanzees studied could be assigned to two different groups: those in which viraemia disappeared in conjunction with or shortly after seroconversion, and those remaining viraemic for many weeks after the appearance of antibodies.

Virus safety of human immunoglobulins: efficient inactivation of hepatitis C and other human pathogenic viruses by the manufacturing procedure.

Human immunoglobulins are plasma derivatives with a low risk of transmitting viral infections. To the present, no proven case of human immunoglobulins transmitting human immunodeficiency viruses has been reported. However, there have been a few reports on the transmission of hepatitis C virus by these plasma proteins.

A rabies-specific human monoclonal antibody that protects mice against lethal rabies.

According to a recommendation from WHO (World Health Organisation) for prevention of a possible rabies infection, active vaccination has to be combined with application of immunoglobulin to get a fast protective effect. At present, preparations of purified human or equine rabies-specific immunoglobulin are used. We have generated a human rabies-specific monoclonal antibody (huMAb) by immortalization of human B-cells with Epstein Barr Virus (EBV), followed by fusion with a mouse myeloma cell.

Protection against European isolates of tick-borne encephalitis virus after vaccination with a new tick-borne encephalitis vaccine.

A highly purified, inactivated tick-borne encephalitis (TBE) virus particle vaccine has been developed. In this study we report on the efficacy of this new vaccine to protect against TBE virus isolates from different geographical areas of Europe and the Asian part of the USSR.

Inactivation of retroviruses in biologicals manufactured for human use.

Human immunodeficiency virus may occur in human plasma and mammalian retroviruses in established cell lines used for the production of monoclonal antibodies or recombinant proteins. To avoid any risk of retrovirus infections being transmitted to human patients by human plasma proteins or other biologicals obtained from established cell lines, these products must be free of contaminating retroviruses. This can be achieved by excluding contaminated source material and by establishing manufacturing procedures which inactivate and eliminate retroviruses.

Antibody- and complement-mediated lysis of HIV-infected cells and inhibition of viral replication.

HIV-1-positive antisera were tested for their ability to lyse HIV-1-infected cells in the presence of active complement. Cytolytic effects caused by sera derived from infected humans were slower than those observed with sera from immunised chimpanzees. Lytic but also negative sera were found among HIV-1-infected asymptomatic men as well as among clinical AIDS cases.

Escherichia coli-derived envelope protein gD but not gC antigens of herpes simplex virus protect mice against a lethal challenge with HSV-1 and HSV-2.

Immunization studies with HSV-1 and HSV-2 envelope proteins expressed in Escherichia coli were performed. After active immunization of mice with a gD-1 antigen (Leu53-Ala312) expressed as a fusion protein, the animals were protected from a lethal challenge with HSV-1 and HSV-2. In addition, antisera from rabbits immunized with the same gD-1 antigen also conferred passive immunity to mice against a challenge infection with either HSV-1 or HSV-2.

Inactivation of HIV-1 and HIV-2 by various manufacturing procedures for human plasma proteins.

Human retroviruses causing AIDS (HIV-1, HIV-2) can occur in human plasma donations. Since HIV-contaminated plasma cannot be completely excluded by testing for anti-HIV-1 (routine plasma screening for anti-HIV-2 has not yet been established), a safeguard against AIDS in therapeutics derived from human plasma can only be achieved by introducing HIV inactivating/eliminating methods into the manufacturing process of plasma derivatives. To investigate the HIV inactivating efficiency of such methods, aliquots of infectious HIV-1 or HIV-2 concentrates were added to a protein preparation, the resulting HIV spiked preparation was then treated according to the method to be studied, and the amount of infectious HIV in this preparation was determined before and after treatment.

Preclinical investigations of the safety, immunogenicity and efficacy of a purified, inactivated tick-borne encephalitis vaccine.

A new tick-borne encephalitis (TBE) vaccine for human use has been developed. TBE virus (TBEV) was propagated in primary chick embryo cells, inactivated by formalin and purified by continuous-flow density gradient centrifugation. The TBE vaccine was tested for innocuity, immunogenicity and protective capacity in a series of laboratory tests.

Inactivation of AIDS-causing retroviruses by the manufacturing procedures for human plasma proteins.

Human retroviruses causing AIDS (HIV) may occur in human plasma. Since HIV contaminated plasma cannot be completely excluded by testing for anti-HIV, AIDS safety of human plasma products can only be achieved by introducing HIV inactivating and/or eliminating methods into the manufacturing procedure. Here we review a number of methods used when manufacturing plasma derivatives at Behringwerke.

Virus safety of a pasteurized antithrombin III concentrate. Preclinical and clinical data.

Blood derived products carry the risk of virus transmission, especially for the hepatitis B virus (HBV), non-A/non-B virus(es) (NANBV) and human immunodeficiency virus (HIV). The precautionary measures for guaranteeing the virus safety of the pasteurized antithrombin III concentrate Kybernin HS/P are described and the efficacy of these measures is demonstrated by in vitro studies and by chimpanzee trials. The inactivation rate is greater than or equal to 10(6.

A strategy for testing established human plasma protein manufacturing procedures for their ability to inactivate or eliminate human immunodeficiency virus.

The manufacturing procedures used for the preparation of human plasma proteins that were established before AIDS was first described may reasonably be expected to provide AIDS safe products. Such manufacturing procedures are heat treatment at 60 degrees C in solution for ten hours, described as pasteurization, preparation of human immunoglobulins by ethanol precipitation, pepsin treatment, and sulfonation. To test whether these methods effectively inactivated and/or eliminated the AIDS causing human immunodeficiency virus (HIV), nine volumes or more of plasma or a plasma fraction taken from a production lot were spiked with HIV using one volume of a HIV concentrate and were then subjected to exactly the same procedure as that specified for the manufacturing process.