Objective: The pathogenic role of TT virus (TTV) is not well known, especially during chronic hepatitis C virus (HCV) infection. We retrospectively investigated the presence of TTV DNA in the plasma of patients with chronic HCV infection and compared the characteristics of TTV-DNA-positive and -negative groups.
Methods: Between November 1996 and November 1998, 234 patients were included. Inclusion criteria were persistently elevated serum alanine aminotransferase (ALT) levels, anti-HCV and HCV-RNA positivity, and seronegativity for hepatitis B virus and human immunodeficiency virus markers. TTV DNA was amplified in nested polymerase chain reaction with TTV-specific primers, and products were analyzed by agarose-gel electrophoresis. Data were analyzed using the chi2, Fisher's exact test, or Mann-Whitney test, as appropriate.
Results: TTV DNA was detected in 19 (8.1%; 95% confidence interval: 4.6-11.6%) patients. TTV-DNA-positive and TTV-DNA-negative patients did not differ statistically for age, gender ratio, source of HCV infection, HCV disease duration, biological parameters, histological grade, HCV-RNA load, or HCV genotype. Although nonsignificant (p = 0.21), there was a trend for a higher prevalence of TTV DNA in patients with an unknown cause of HCV infection (4/22, 18.2%) than in intravenous drug users (4/84; 4.8%), in those exposed to potential risk factors (4/49; 8.2%), or in those having received blood transfusion (7/79; 8.9%).
Conclusions: Because the rates of HCV replication and the severity of liver lesions in TTV-DNA-negative and -positive patients were similar, the hepatic pathogenicity of TTV in chronic hepatitis C patients is questionable.