Route of TT virus infection in children

TT virus (TTV) is a novel viral agent, detected recently in non-A to E hepa titis cases. Little is known about its natural history or routes of transmi ssion in childhood. For the detection of serum TTV DNA, semi-nested polymer ase chain reaction (PCR) was carried out using TTV-specific primers and TTV nucleotide sequences were determined by the dideoxy chain-mediated termina tion method. Five of the 70 children studied (including 20 hepatitis B viru s [HBV] carriers, 40 children born to HBV carrier mothers and 10 children b orn to hepatitis C virus [HCV] carrier mothers) had serum TTV DNA. Three of the 5 children had siblings (4 in total), so that a total of 9 children we re studied to determine the time of initial serum TTV DNA detection. In the 8 seropositive children, the time of serum TTV DNA detection ranged from 6 to 14 months after birth, and TTV DNA persisted thereafter throughout the follow-up period. The TTV DNA-negative child was assessed most recently at 6 months of age. TTV DNA was detected in only 2 of the 4 mothers tested (fa milies 2 and 3). When 271-bp TTV DNA fragments from each of the 8 children were sequenced, the degree of homology between siblings in families 1-3 was 100%, 99.5%, and 92.3%, respectively. The degree of homology between child -mother pairs of families 2 and 3 was 99.5-100% and 62.6-63.9%, respectivel y. The distribution of different TTV strains was consistent within families , except for family 3. None of the TTV-infected children had elevated level s of alanine aminotransferase or clinical signs of liver disease. (C) 1999 Wiley-Liss, Inc.