Pathological and molecular-based virological studies of TTV and s-TTV infection

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1) Detection of TTV DNA in body fluids :TTV DNA was detected in the saliva of 7 (7/10 ; 70%) individuals and the semen of 6 (6/10 : 60%) individuals, respectively. In addition, TTV DNA was also detected frequently (8/16 ; 50%) in bile juice, suggesting a fecal-oral TTV transmission route.2) Observation of viral particles :Under the electron microscopic examination, viral-like particles (VLP) with 20-30nm in diameter were found in bile juice from a patient infected with TTV. VLPs were found in fractions with a density of 1.24-1.28/ml in continuous gradient of CsCl.3) Infection of simian TTV (s-TTV) to humans :s-TTV DNA was determined by nested PCR using s-TTV-specific primers designed from untranslated region of s-TTV genome. s-TTV DNA sequence was detected in 3 of 200 (1.5%) healthy adults. On the other hand, s-TTV DNA was detected in 18 of 260 (6.9%) Japanese patients with liver diseases (chronic hepatitis 10/217 ; 4.6%, cirrhosis 4/28 ; 142%, hepatocellular carcinoma 4/12; 33.3%). 55.5% (10/18) of patients were positive for s-TTV alone. s-TTV DNA was detected in 10/151 (6.6%) patients with liver diseases of unknown etiology. Nucleotide sequence analyses in 20 patients confirmed that these PCR products were derived from s-TTV genome sequences and nearly 85% identical to those of s-TTV prototypes from chimpanzees. Phylogenetic analysis demonstrated that all s-TTV isolates from humans were distinguished clearly from the human TTV isolates. Furthermore, s-TTV in humans was classified into 2 different genotypes as well as simians.