Virus inactivation by solvent/detergent treatment and the manufacture of SD-plasma.

Solvent/Detergent (SD) is an extraordinarily effective means for eliminating enveloped viruses from plasma and plasma products. The safety margin suggested by the rapid and complete kill of enveloped viruses observed in the laboratory has been confirmed repeatedly by groups worldwide and by thirteen years of routine clinical use encompassing an estimated 35 million doses of a wide variety of products. Throughout this time, there has not been a single documented case of enveloped virus transmission by an SD-treated product. This record of safety spawned the development of SD-treated plasma as a substitute for fresh frozen plasma (FFP) and has encouraged the adoption of SD for the treatment of non-blood products such as monoclonal antibodies and those derived from recombinant DNA procedures. This review summarizes the use of SD treatment, including its use in combination with other viral elimination procedures, and also summarizes Vitex's initial experience in the manufacture of SD-Plasma, recently licensed by the U.S. FDA.

Inactivation of lipid-enveloped viruses in labile blood derivatives by unsaturated fatty acids.

Virus sterilization of blood plasma derivatives by addition of several naturally occurring fatty acids was evaluated using vesicular stomatitis virus and Sindbis virus as markers for lipid-enveloped virus inactivation and human immunodeficiency virus (HIV). Inactivation of greater than or equal to 10(4) tissue culture infectious doses (TCID50) of marker viruses added to antihemophilic factor (AHF) concentrates, with 60-100% retention of AHF activity, was achieved with oleic, 11-eicosenoic, linoleic, linolenic, palmitoleic and arachidonic acids. Elaidic, gamma-linolenic, palmitic, and arachidic acids and another fat-soluble compound previously reported to inactivate virus, butylated hydroxytoluene, were less effective. A long chain mono- but not a di- or triglyceride also displayed virucidal properties. Evaluation of the inactivation of HIV added to an immune globulin solution on exposure to 0.033% sodium oleate for 20 min indicated inactivation of greater than or equal to 10(3.4) TCID50. The degree of virus inactivation depended on the sample composition. A favorable balance was achieved between degree of virus inactivation and retention of protein function for AHF concentrate, prothrombin complex concentrate, antithrombin III concentrate, and immune globulin solution on incubation with 0.033% (w/v) sodium oleate at 24 degrees C for 4-6 h. Virus inactivation in whole plasma and plasma cryoprecipitate was not complete despite use of higher concentrations of sodium oleate and/or incubation at 37 degrees C. Reduced virus kill in these less purified derivatives probably is a consequence of their endogenous lipid and/or albumin.

Inactivation of viruses in labile blood derivatives. I. Disruption of lipid-enveloped viruses by tri(n-butyl)phosphate detergent combinations.

Use of the organic solvent, tri(n-butyl)phosphate (TNBP), and detergents for the inactivation of viruses in labile blood derivatives was evaluated by addition of marker viruses (VSV, Sindbis, Sendai, EMC) to anti-hemophilic factor (AHF) concentrates. The rate of virus inactivation obtained with TNBP plus Tween 80 was superior to that observed with ethyl ether plus Tween 80, a condition previously shown to inactivate greater than or equal to 10(6.9) CID50 of hepatitis B and greater than or equal to 10(4) CID50 of Hutchinson strain non-A, non-B hepatitis. The AHF recovery after TNBP/Tween treatment was greater than or equal to 90 percent. Following the reaction, TNBP could be removed from the protein by gel exclusion chromatography on Sephadex G25; however, because of its large micelle size, Tween 80 could not be removed from protein by this method. Attempts to remove Tween 80 by differential precipitation of protein were only partially successful. An alternate detergent, sodium cholate, when combined with TNBP, resulted in almost as efficient virus inactivation and an 80 percent recovery of AHF. Because sodium cholate forms small micelles, it could be removed by Sephadex G25 chromatography. Electrophoretic examination of TNBP/cholate-treated AHF concentrates revealed few, if any, changes in protein mobility, except for plasma lipoprotein(s).

Inactivation of viruses in labile blood derivatives. II. Physical methods.

The thermal inactivation of viruses in labile blood derivatives was evaluated by addition of marker viruses (VSV, Sindbis, Sendai, EMC) to anti-hemophilic factor (AHF) concentrates. The rate of virus inactivation at 60 degrees C was decreased by at least 100- to 700-fold by inclusion of 2.75 M glycine and 50 percent sucrose, or 3.0 M potassium citrate, additives which contribute to retention of protein biologic activity. Nonetheless, at least 10(4) infectious units of each virus was inactivated within 10 hours. Increasing the temperature from 60 to 70 or 80 degrees C caused a 90 percent or greater loss in AHF activity. An even greater decline in the rate of virus inactivation was observed on heating AHF in the lyophilized state, although no loss in AHF activity was observed after 72 hours of heating at 60 degrees C. Several of the proteins present in lyophilized AHF concentrates displayed an altered electrophoretic mobility as a result of exposure to 60 degrees C for 24 hours. Exposure to lyophilized AHF to irradiation from a cobalt 60 source resulted in an acceptable yield of AHF at 1.0, but not at 2.0, megarads. At 1 megarad, greater than or equal to 6.0 logs of VSV and 3.3 logs of Sindbis virus were inactivated.

Preparation of antihemophilic factor and fibronectin from human plasma cryoprecipitate.

Starting with human plasma cryoprecipitate, fibronectin was separated from antihemophilic factor (AHF) by fractional precipitation under mild conditions resulting in excellent recovery of AHF in the supernatant solution of the cryoprecipitate. Separation of fibronectin enabled accelerated sterile filtration of the supernatant solution containing AHF even after three- to fourfold concentration (by ultrafiltration) to desired potency. The sterile AHF concentrate, dispensed at 1000 u per vial and lyophilized, was completely dissolved within 3 minutes upon addition of 30 ml of pure water. The expected increment in circulating factor VIII and its hemostatic effects were found following intravenous infusion into factor VIII-deficient patients. Yield of AHF of five successive batches, each starting with the cryoprecipitate from some 12,000 units of fresh-frozen plasma, averaged 51 percent. The fibronectin precipitate was purified by affinity on insolubilized gelatin with chaotropic elution at pH 5.5 followed by removal of the chaotrope by diafiltration. Thermal denaturation of adventitious fibrinogen resulted in electrophoretically pure fibronectin which, following lyophilization and reconstitution with pure water, retained biological properties in an in vitro assay designed to reflect opsonic activity. The yield of fibronectin for seven successive batches, each starting with the cryoprecipitate from some 900 units of fresh-frozen plasma, averaged 10 percent.

Development of hemagglutination assays II. Enhancement in the sensitivity of an RPHA test for HBsAg.

Studies were undertaken to enhance the sensitivity of a previously developed RPHA test for HBsAg. A net increase in sensitivity of approximately 3-fold was achieved by modifying the elution procedure used to purify chimpanzee anti-HBs by affinity chromatography. A further 3- or 4-fold sensitivity increase was achieved by increasing the volume of specimen tested. A concomitant increase in nonspecific agglutination usually observed with increased specimen size was avoided by incubating the reaction mixture at 37 or 45 degrees C. Evaluation of the test in detection of HBsAg in blood obtained from volunteer donors indicates that the materials produced at the New York Blood Center using the modified test protocol compare favorably with a commercial RPHA test. Modifications which did not contribute toward enhancing sensitivity are also reported.

Thyroxine binding by hepatitis B surface antigen.

Thyroxine and triiodothyronine binding sites are present on the 20-nm spherical particles associated with hepatitis B surface antigen (HBsAg). Thyroxine-treated HBsAg has a buoyant density of 1.26 g/cm-3 in CsCl and appears under the electron microscope as a hexagonal particle with a center-to-vertex distance of 10 nm. These results provoke questions concerning the origin of thyroid hormone binding sites on HBsAg and a possible relationship between thyroid status and HBsAg antigenemia in humans.

A new reversed passive hemagglutination test for detection of HBsAg.

A new reversed passive hemagglutination test for HBsAg, termed Raphadex B, has been developed using immunochemically purified chimpanzee anti-HBs bound to stabilized human erythrocytes. The test has been found to have equivalent sensitivity to the Ausria 125I radioimmunoassay, and detected a similar number of HBsAg-containing specimens in screening of volunteer blood donors. This method offers an economical approach to third generation methodology for hepatitis B screening of blood donors.

Hepatitis B antigen: antigenic sites related to human serum proteins revealed by affinity chromatography.

Hepatitis B antigen-associated particles, isolated from sera of antigen carriers, were submitted to affinity chromatography on columns of insolubilized antibodies to normal human plasma. The particles adsorbed to the immunosorbent at pH 7.2 and were subsequently eluted at pH 2.2. Exposure of the particles to 8 M urea, 5 M KI, pH 2.2, detergents, organic solvents, or proteolytic enzymes failed to prevent their subsequent adsorption to the immunosorbent. This suggests that antigenic determinants related to human plasma proteins are constituent components of hepatitis B antigen-associated particles. These determinants are distinct from the group-specific (a) and subtype-specific (d or y) sites of the hepatitis B antigen and appear to be related to antigenic specificities on prealbumin, albumin, apolipoproteins C and D, and the gamma-chain of immunoglobulin G.