Presence of a newly described human DNA virus (TTV) in patients with liver disease

Background A newly described DNA virus, named transfusion-transmitted virus (TTV), was recently detected with high prevalence in Japanese patients with fulminant hepatitis end chronic liver disease of unknown aetiology. We investigated the presence of this virus in patients with liver disease in the UK to find out whether TTV infection is associated with liver damage. Methods We used semi-nested PCR to amplify TTV DNA from serum samples from 126 adults, of whom 72 were patients with a range of chronic liver diseases, 24 had spontaneous resolution of infection with hepatitis C virus (HCV), and 30 were normal controls. Direct DNA sequencing and phylogenetic analysis were used to characterise the TTV isolates. Findings We detected TTV DNA in 18 (25%) of the 72 patients with chronic liver disease, which was not different from the 10% prevalence in normal controls (p=0.15). The rate of TTV DNA was similar among patients with various liver diseases. The majority of TTV-positive cases had no biochemical or histological evidence of significant liver damage. TTV DNA sequencing of nine isolates showed the same genotypic groups as in Japan: three patients were infected with genotype 1, which showed 4% nucleotide divergence, and six patients were infected with genotype 2 with 15-27% divergence. Interpretation The high prevalence of active TTV infection in the general population, both in the UK and in Japan, and the lack of significant liver damage, suggest that TTV, similar to hepatitis G virus (HGV), may be an example of a human virus with no clear disease association.