Detection of TT virus infection and nucleotide sequence analysis of partial positives samples from different populations

  Objective   To investigate the prevalence and gene types of TT virus infection in different people (populations).

  Methods   TTV DNA were detected by a hemi-nested polymerase chain reaction (PCR) assay in sera from blood donors, hepatitis patients, children and in sera from mothers and paired cord. Several amplified products were sequenced and the data were analyzed with the computer programs.

  Results   The total detection rate of TTV DNA was 24.29% (111/ 457) in all objects. The positive rate of TTV DNA in various populations were as follows: In donors, 16.6%(16/96)with elevated transaminase level while 36.3%(36/99)with nomal transaminase level and there were significant differences between them. In hepatitis patients, the total detection rate of TTV DNA was 54.16% and the positive rate was 87.5%(7/ 8)in non A-G hepatitis while 50% in patients whose diagnosis were clear. In children, TTV DNA was detected in 14 out of 110(12.73%).TTV DNA was detected in 5 of 40 sera of the mother, and 1 of 40 cord sera of infants was TTV DNA positive while his mother was TTV infected.12 sequences of 222 bp of ORF1 selected form the positive samples were analyzed and compared with sequenced representation of publics isolates which revealed that 11 of them can be classified into 5 subgroups of group G 1 and G2, and another may be a new subgroup of G1.

  Conclusion   Elevation of ALT was associated with TTV infection, which may be one of the cause of non A-G hepatitis. There may be other transmitted routes besides blood-borne. TTV can cross the placenta and mother-to-fetus transmission is an important mean.