Objective: To study the molecular epidemiology of new hepatitis TT virus (TTV) infection, its distribution in population and its role in pathogenesis of hepatitis in some parts of our country.
Methods: TTV DNA in serum samples was detected by nested-polymerase chain reaction, partial gene of various geographic strains of TTV was cloned and sequenced, and their genetic variation was analyzed.
Results: Forty-four of 112 cases with non-A to G hepatitis from Shenzhen, Guangdong province, Nanjing, Jiangsu province, Beijing and Shengyang, Liaoning province were positive for TTV DNA with a positive rate of 42.9%, but only three of 102 cases of hepatitis A-G was positive, with a positive rate of 2.9% (chi 2 = 42.8, P < 0.01). Positive rate of TTV DNA was significantly higher in blood donors with abnormal ALT but without infection markers of hepatitis A-G (34.6%) than in those with normal ALT (16.8%) (chi 2 = 4.5, P < 0.05). Sequencing analysis showed that more than 98% of their nucleotides were analogous between strains of TTVCHN002 from Shenzhen and Nanjing, and TTVSHB015 from Beijing, and more than 97% analogous between the above-mentioned strains and Japanese ones.
Conclusion: There existed TTV infection in both north and south China. TTV infection correlated closely with abnormal ALT, which might be an important pathogen for non-A, non-B, hepatitis G. There were somebodies infected with TTV in the normal healthy population, similar to that of "chronic carrier status" in hepatitis B.