[Validation of the virus inactivation capacity of a procedure of human plasma albumin purification by chromatography].

Almost the whole of the human plasma albumin preparations intended for clinical or biological uses is at present fractionated by cold ethanol precipitation technics based on the Cohn method. However, ion-exchange chromatographic processes have been recently developed. The aim of this work was the evaluation of the viral inactivation efficacy of an automated industrial chromatographic process allowing fractionation of 350 to 400 l of plasma per cycle (one precipitation step, three ion-exchange chromatography steps using the Spherodex-Spherosil gels--Sepracor-IBF, Villeneuve la Garenne, France--and one pasteurization step. Three relevant viruses were selected for this validation study: the hepatitis B virus (HBV), the poliomyelitis virus and the human immunodeficiency virus (HIV). In order to comply with EEC and FDA regulatory documents, significant amounts of the tested viruses were spiked into the different fractions obtained during the various purification steps and their removal or inactivation during the subsequent step were determined. The validation study was performed under conditions which mimic the manufacturing process using fractions obtained during a semi-industrial fractionation. Moreover, residual viral infectivity was checked on after elution and washing of the columns for each chromatographic step. Results have pointed out: a) an overall reduction of 4.4 log 10 for HBV. Infectivity is judged by a combination of several markers and the DNA polymerase activity is the most affected particularly during the three ending purification steps; b) an overall reduction in virus titer > 10 log 10 for the poliomyelitis virus; c) an overall reduction in virus titer > 10 log 10 for HIV (four of the five steps have an important potential to inactivate this virus increasing the safety of the process). Moreover, no residual viral infectivities were detected after washing of the columns. In conclusion, this study showed the viral safety of human albumin purified using the chromatographic Spherodex-Spherosil process. As had been observed for fractionation by means of ethanol, the pasteurization step is necessary to ensure inactivation of two of the three viruses tested (HBV and poliomyelitis virus). This validation study allowed the preparation of a manufacturing and controls document for albumin and a marketing authorization has been issued by the "Laboratoire National de la Santé" (LNS, France).