Transfusion-associated TT virus infection and its relationship to liver disease

Abstract

TT virus (TTV) has been proposed as the causative agent of non-A to E hepatitis. We studied the association between TTV viremia and biochemical evidence of hepatitis in blood donors and prospectively-followed patients. TTV was found in 7.5% of 402 donors and in 11.0% of 347 patients before transfusion. The rate of new TTV infections was 4.7% in 127 nontransfused, and 26.4% in 182 transfused patients (P F .0001). The risk of infection increased with the number of units transfused (P F .0001). The rate of new TTV infections in 13 patients with non-A to E hepatitis (23.2%) was almost identical to the rate in 124 patients who were transfused, but did not develop hepatitis (21.8%). Of 45 patients with acute hepatitis C, 40.0% were simultaneously infected with TTV. TTV did not worsen the biochemical severity (mean ALT: 537 in TTV؉; 550 in TTV؊) or persistence of hepatitis C. In non-A to E cases, the mean ALT was 182 in those TTV-positive and 302 in TTV-negatives. No consistent relationship between alanine transaminase level and TTV DNA level was observed in 4 patients with long-term, sequential samples. Of 21 viremic subjects, 67% cleared TTV within 5 years (38% in 1 year); 33% were viremic throughout follow-up extending to 22 years. We conclude that TTV is a very common, often persistent infection that is transmitted by transfusion and by undefined nosocomial routes. We found no association between TTV and non-A to E hepatitis and no effect of TTV on the severity or duration of coexistent hepatitis C. TTV may not be a primary hepatitis virus. (HEPATOLOGY 1999;30:283-288.)TT virus (TTV) was discovered in 1997 by representational difference analysis of serial serum specimens from Japanese patients with transfusion-associated non-A to G hepatitis. 1 Because of a temporal association between TTV viremia and elevations in serum alanine transaminase (ALT) level in 3 of 5 patients studied, TTV was proposed as the causative agent of non-A to G hepatitis. 1 TTV was initially described as a single-stranded DNA virus of approximately 3,800 base pairs (bp) and considered to be a member of the parvovirus family. 2 A subsequent analysis suggested that it was a single-stranded circular DNA virus in the circovirus family. 3 These genomic characterizations have been questioned and, at present, the agent has not been definitively classified. Seroepidemiological studies have shown TTV to have global distribution. 2,[4][5][6] Although the potential association of TTV with cryptogenic hepatitis is intriguing, the pathological and clinical significance of this virus remains to be established. To assess more fully the etiological role of TTV in the causation of hepatitis, we determined the frequency of acute TTV infections and their relationship to hepatitis in a cohort of prospectivelyfollowed transfusion recipients who did and did not develop hepatitis and in nontransfused controls. Prevalence of the agent was assessed in blood donors and in patients at the time of hospital admission. MATERIALS AND METHODS Selection of Patients in Variou...

Molecular characterization of Torque teno virus and SEN virus co-infection with HIV in patients from Southern Iran

“…TTV was fi rst detected in subjects with post-transfusion hepatitis and indicated as a possible etiological source of non A-non C hepatitis 12 . Although TTV DNA was present at high concentrations in liver tissue and in sera of patients with liver disease 13 , several studies have reported a high endemicity of infection in subjects with no evidence of hepatitis 14 . Therefore, the role of TTV as a causative agent of liver disease is unclear.…”

Liver Pathology: Cirrhosis, Hepatitis, and Primary Liver Tumors. Update and Diagnostic Problems

“…Another recently described virus is the TT virus, a DNA virus seen associated with hepatitis in Japan, but questions still remain as to its significance (68,69).…”

Molecular Detection Method for All Known Genotypes of TT Virus (TTV) and TTV-Like Viruses in Thalassemia Patients and Healthy Individuals

“…To confirm these findings, we genetically characterized 420 clones of NG primer products from 32 thalassemia patients and 8 healthy individuals, as well as 50 PCR products amplified by TT and RD037/ 038/051/052 primers from 50 thalassemia patients and 96 TLMV-S primer product clones from 16 thalassemia patients. We detected TTV genotypes 1 to 3, 9 to 13,14,16,18,22,23, and group 5 (JT33F/JT34F/CT39F/CT44F); SENV genotypes A, B, D, and H; and four TLMV groups (three known plus one newly identified). TTV genotypes 4 to 8,15,17,19, and 20 including SENV (genotypes C and E to G) were not found, presumably due to their low prevalence in the test populations.…”

“…TTV and TTLVs are widely distributed geographically, with an extremely high prevalence of viremia in the general population, particularly in tropical countries (32) and parts of Asia (6). Mixed-genotype infections are therefore common, particularly in thalassemia patients, due both to the high frequency of viral transmission through repeated therapeutic blood transfusions and the persistent nature of the viruses (5,9,14,15,18,23,31). TTV and TTLVs demonstrate an extremely wide range of sequence divergence.…”