Abstract
The genomic DNA of a novel virus named TT virus (TTV), associated with posttransfusion hepatitis of unknown etiology, was cloned from plasma of a blood donor with an elevated transaminase level but without serological markers of known hepatitis viruses, and its sequence of 3739 bases was determined. TTV had a density of 1.26 g/cm 3 in sucrose, which did not change after the treatment with Tween 80. The viral genome was sensitive to DNase I and Mung Bean Nuclease. Hence, TTV would be an unenveloped, single-stranded DNA virus. Two possible open reading frames in different frames were identified, capable of encoding 770 and 202 amino acids, respectively. When a partial sequence of 356 bases was compared among TTV isolates from 78 sera from blood donors and hepatitis patients, it showed considerable divergence with differences of up to 30%. Oligonucleotide primers were designed on two well-conserved regions for the detection of TTV DNA in serum and biopsied liver tissues by polymerase chain reaction. TTV DNA was detected in sera from 9 of 19 (47%) patients with fulminant hepatitis and 41 of 90 (46%) patients with chronic liver disease of unknown etiology. TTV DNA was detected in liver tissues of all the five patients tested, in titers equal or 10–100 times higher than those in the corresponding sera. These results indicate that TTV would be responsible for a part of acute and chronic liver disease of unknown etiology.
Published Version
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