Prevalence and pathogenicity of TT virus infection in patients with liver diseases

AIM:To investigate the prevalence of TT virus in patients with liver diseases and the association between liver diseases and TTV, especially genotype G1. METHODS:TTV DNA in serum were examined in 83 patients with non A-non E hepatitis,75 patients with chronic liver diseases and 105 general people. TTV was detected by PCR with two sets of primers, one of which was located in the 5' UTR and the other was in the ORF1. The genotyping assay was based on RFLP. Some PCR products were sequenced. RESULTS:The positive rates of TTV were 95.2%, 93.3% and 87.6% in patients with nonA-nonE hepatitis, patients with liver diseases and general people respectively. There were no significant differences among the rates (P >0.05). The positive rates of genotype G1 were 32.5%, 38.7% and 19.0% in three groups respectively. The positive rates of G1 in patients with nonA-nonE hepatitis and in patients with liver diseases were significantly higher than that in the general people (P 0.05). The positive rate of G1 was 40% in patients with liver cirrohosis or carcinoma associated with HCV infection and 100% in patients with chronic C hepatitis. There were no significant differences between them (P >0.05). There was no significant difference in age, gender, levels of ALT between G1 positive and negative patients with chronic B hepatitis or HBsAg carrier (P >0.05). TTV-positive rate in the general people aged 21-30 (72.2%) was significantly lower than that in the general people aged 31-40 (96.2%, P <0.01) and aged 41-50 (93.1%, P <0.05). The positive rate of G1 infection in the general people was not related to age and gender. CONCLUSIONS:There is very high prevalence of TTV infection in general population and patients with liver diseases. Genotype G1 is associated with liver disease,however, its pathogenicity may be very weak.