Objective   To detect TT virus(TTV)DNAs of group1, group 4 and group 5 in serum samples obtained from healthy infants and volunteer blood donors living in Jiujiang City in an attempt to shedlight on the prevalence of TTV mixed infection of examined genetic groups.

  Methods   N22 PCR, G4 PCR and G5 PCR were performed to test specific TTV DNA of group1, group 4 and group 5, respectively, in serum samples from 86 infants and 129 blood donors.

  Results   TTV DNA of group1 was 16.3%(14/86)in infants and 35.7%(46/129)in blood donors detected by N22 PCR, while those of group 4 and group 5 were 40.7%(35/86)and 24.4%(21/86)in infants as well as 82.9%(107/129)and 46.5%(60/129)in blood donors, respectively.

  Conclusion   High prevalence of TTV infection was identified among the examined infants and adults detected by UTRPCR, however, the prevalence of TTV infection differed by genetic group.72.5% of 7-to 12-month-old infants amd 82.9% of adults were infected with group 4 TTV isolates, suggesting TTV group 4 was the prevalent isolates in the examined population.On the other hand, an age-dependent increase of mixed infection of examinde TTV genetic groups was observed in infants, and the mixed infection with 3 different group isolates of TTV was significant less than that of adults in the same region(P < 0.001).