TT virus (TTV) is a newly discovered transfusion-transmissible DNA virus, w
hich may cause posttransfusion hepatitis. The virus was detected in 12% of
Japanese blood donors. The aim of the study is to investigate the prevalenc
e and clinical influence of TTV in bone marrow transplant (BMT) recipients.
Sera from 25 BMT recipients obtained 6 to 12 weeks after the transplant we
re examined for TTV-DNA by the seminested polymerase chain reaction. Serial
samples were additionally analyzed in patients with TTV-DNA. Fifteen of 25
recipients (60%) were positive for TTV-DNA after transplant, whereas it wa
s detected in only two of 20 BMT donors (10%). In patients positive for TTV
-DNA before BMT, the amount of TTV-DNA decreased to an undetectable level d
uring the myelosuppressed period after BMT. We also found that there was a
novel group of TTV, G3, classified by the nucleotide sequences. The median
peak alanine aminotransferase (ALT) levels were 135.0 IU/L and 116.5 IU/L (
normal range, 4 to 36 IU/L) in TTV-positive and rm-negative recipients, res
pectively. In one of the seven TTV-positive patients who developed hepatic
injury (ALT > 150 IU/L), a serial change in the serum rm titer showed a goo
d correlation with the ALT level. We concluded that (1) the prevalence of T
TV is high in BMT recipients, (2) TTV might be replicated mainly in hematop
oietic cells, (3) transfusion-transmitted rm may cause persistent infection
, (4) a novel genetic group of TTV. G3, was discovered, and (5) mi does not
seem to frequently cause hepatic injury, although one patient was strongly
suggested to have TTV-induced hepatitis. (C) 1999 by The American Society
of Hematology.