Prevalence of TT virus in plasma pools and blood products

A high prevalence of TT virus (TTV), a novel virus recently identified in t he serum of a patient with posttransfusion hepatitis of unknown aetiology, has been reported in blood donors worldwide, We investigated the presence o f TTV DNA in several lots of blood products and in the corresponding plasma pools. In the process, we determined, from three sets of primers, the one which was most efficient in detecting the viral nucleic acid. This set ampl ifies the region closest to the 3'-end of the TTV genome which was proved, by sequence analysis, to be more conserved than the other two regions. Wher eas all 10 intravenous immunoglobulin and 21 albumin batches were TTV negat ive, 4/5 factor VIII concentrates and 4/10 intramuscular immunoglobulin bat ches were TTV positive. A high prevalence of TTV DNA (70%) was found in the plasma pools that were collected from four different countries,These resul ts confirm the worldwide distribution of this virus and show that TTV is re moved with a varying efficiency during the manufacture of blood products.