Prevalence of TT virus in patients with hepatitis B,C and hepatitis of unknown etiology

Discovery of TT virus in 1997 gave raise to intensive subsequent studies to learn about its structure, features and, what is the most important, about its role in pathogenesis of liver disease. The aim of the work was to analyze prevalence of TTV DNA in patients with diagnosed hepatitis B, C, that of unknown etiology and in healthy blood donors as well. Additionally the divergence of TTV sequence was estimated in selected cases. TTV DNA was detected by PCR technique using specific oligonucleotide primers for coding regions. TT virus has been detected in 25.6% (32/125) HBsAg positive patients and in 23.9% (51/213) HCV infected patients. In healthy blood donors the frequency of TTV was 24.3% (34/140) similarly to that found in HCV and HBV infected patients. The frequency of TTV DNA among patients with hepatitis of unknown etiology was 9.1%. This result was statistically significant lower than in the other groups. When detected sequences have been compared to these from NCBI base the homology result was 71% to 95%, and among different patients and groups of patients identity was 46% to 73%. On the basis of the obtained results it can be concluded that it is very unlikely that TTV coinfection plays any significant role in HCV or HBV infection. The hypothetical role of TTV infection in the etiopathogenesis of cryptogenic chronic hepatitis has not been confirmed. The results obtained in the small group of patients with hepatitis of unknown etiology are not conclusive and should be taken with some precaution. The final conclusion is the TTV coinfection does not contribute to the liver pathology. The divergence of TTV sequences may explain the various frequency of TTV viremia reported by other authors.