DETERMINATION OF THE INACTIVATION KINETICS OF HEPATITIS-A VIRUS IN HUMAN PLASMA PRODUCTS USING A SIMPLE TCID50 ASSAY

The transmission of hepatitis A virus (HAV) associated with use of FVI II concentrates has been reported in a number of European countries. A ll of these cases were associated with products inactivated by use of solvent detergent treatment. These reports have emphasized the necessi ty of evaluating virus inactivation methodologies for their ability to inactivate HAV. Such studies had previously been hampered by the diff iculties associated with titration of HAV, because of the minimal cyto pathic effect of most strains of virus on tissue culture cells. We hav e developed a simple, rapid, TCID50 virus titration system using a cyt opathic strain of HAV which allows extensive kinetic studies of HAV in activation. This has been compared with the standard radioimmunofocus forming (RFF) assay which is presently used for HAV titration. The rep roducibility of the TCID50 assay was demonstrated to be equal to that of the RFF assay and the 95% confidence intervals for titres determine d by both assays were also equal. The thermal stability of the cytopat hic strain was studied and shown to be equivalent to that of a noncyto pathic strain. The kinetics of HAV inactivation by heating in aqueous solution were compared to those of HIV-1 and a number of model viruses . It was demonstrated that HAV was highly stable, with 5 hours heat tr eatment at 60 degrees C in aqueous solution being required to inactiva te 5.8 log(10) virus. In contrast to heating in aqueous solution, lyop hilization followed by 1 hour vapor heating at 60 degrees C was suffic ient to inactivate 5.9 log(10) HAV. (C) 1996 Wiley-Liss, Inc.