Higher prevalence and viral load of TT virus in saliva than in the corresponding serum: Another possible transmission route and replication site of TT virus

Although TT virus (TTV) is transmissible by blood or blood products, many p atients with no history of transfusion of blood and blood products have bee n shown to be infected, suggesting other possible routes of transmission. T o investigate the transmission routes and replication sites of TTV, 85 pair ed saliva and serum samples were studied by semi-nested polymerase chain re action. The prevalence of TTV DNA was 38% (32/85 samples) and 21% (18/85) i n saliva and serum, respectively. Fifteen patients had TTV DNA both in sali va and serum. Six out of fifteen patients had significantly higher viral ti ters in saliva than in serum, but none had higher titer in serum than in sa liva. When the 222 base-pair nucleotide sequences of PCR products amplified from the samples were analyzed, 12 patients had the same genotype/subtype in saliva and serum and exhibited high homology (96-100%). The other 3 had different genotypes/subtypes in saliva and serum, and the homology was 61.9 -87.2%. Mixed infection was observed both in saliva and serum. Further stud ies are required to determine if a subgroup of TTV has tropism to saliva. T he high prevalence and viral load of TTV in saliva suggest that salivary fl uid may be a possible route of transmission of TTV and that TTV might repli cate not only in liver tissue but also in other tissues such as oropharynge al tissues and/or salivary glands. J. Med. Virol. 62: 537-537, 2000. (C) 20 00 Wiley-Liss, Inc.