High prevalence of TT virus (TTV) infection in patients on maintenance hemodialysis: frequent mixed infections with different genotypes and lack of evidence of associated liver disease.

Recently, a novel DNA virus, TT virus (TTV), was identified in patients with post-transfusion non-A-G hepatitis. We analyzed the prevalence and clinical implications of TTV infection in a cohort of 96 Spanish patients on long-term hemodialysis. TTV DNA was detected by nested PCR in 51 (53%) of 96 patients, a prevalence significantly higher than that found in healthy blood donors. Persistent liver test abnormalities were found in only 2 (7.7%) of 26 patients infected with TTV alone, compared with 12 (75%) of 16 patients infected with hepatitis C or hepatitis B virus, or both (P < 0.01). Mixed infections with multiple strains of TTV, including different major genotypes, were common in patients on hemodialysis. These patients had received a significantly greater number of blood units (22.7 +/- 20) compared with patients apparently infected with a single strain of TTV (8.9 +/- 11) (P = 0.01). Phylogenetic analyses of TTV from infected patients identified strains of genotypes 1, 2, 3, and 4. In summary, TTV infection was common in patients on hemodialysis but was not associated with liver disease