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[Molecular epidemiology of TT virus infection in some parts of China].

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.