Infection of TT virus in patients with idiopathic pulmonary fibrosis

The precipitating factors of idiopathic pulmonary fibrosis (IPF) have not been elucidated. Recently, a novel DNA virus named TTvirus (TTV) was discovered in a patient with post-transfusion hepatitis of unknown aetiology. TTV is a circular, single-stranded DNA virus of 3.8 kB. To evaluate the relationship between TTV and IPF, the sera of 33 patients with IPF were tested for the presence of TTV DNA by semi-nested polymerase chain reaction. TTV DNA was detected in 12 (36.4%) IPF patients, The serum lactate dehydrogenase (LDH) level was significantly higher in the IPF patients with TTV than in those without TTV (802 +/- 121 vs. 530 +/- 49 IUI-1, P<0.05), Six (50%) of 12 patients in the TTV DNA-positive group died during the observation period, while only six (28.6%) of 21 patients in the TTV DNA-negative group died. The 3-year-survival rate was significantly lower in the TTV DNA-positive group than in the TTV DNA-negative group (58.3% vs. 95.2%, P<0.02). Replicative intermediate forms of TTV DNA were detected in the lung specimen from a TTV-infected IPF patient. TTV infection influences the disease activity and prognosis of IPF in some cases. Further studies are required to elucidate the clinical significance of TTV in IPF. (C) 2001 Harcourt Publishers Ltd.