TTV-A Novel DNA Virus in Search of a Disease?
TTV-A Novel DNA Virus in Search of a Disease?
ABSTRACTS & COMMENTARY
Sources: Simmonds P, et al. Detection of a novel DNA virus (TTV) in blood donors and blood products. Lancet 1998;352:191-195; Naoumov NV, et al. Presence of a newly described human DNA virus (TTV) in patients with liver disease. Lancet 1998;352:195-197.
Simmonds and colleagues in edinburgh examined plasma of unpaid blood donors by PCR for evidence of a recently described DNA virus, TTV (transfusion-transmitted virus). All had undetectable antibody to HCV, HIV-1, HIV-2, and HBsAg. TTV viremia was detected in 19 (1.9%) of 1000 donors. The virus was present at a geometric mean concentration of 620 copies/mL (range, 50-50,000 copies/mL).
TTV DNA was identified in plasma of 23 (27%) of 84 hemophiliacs treated before 1986 with non-virally inactivated concentrate but in only one (5%) of 19 who had received only inactivated concentrate (P = 0.04). Nonetheless, TTV DNA was detected in approximately one-half of factor VIII and IX concentrates tested, whether they had undergone solvent or detergent treatment; although these inactivation steps did not eliminate viral DNA, it appeared to reduce viral infectivity. It could not be detected in heat-treated factor VIII concentrate.
Four (19%) of 21 patients with acute fulminant hepatitis who had no evidence of infection with known hepatitis viruses A-E had TTV viremia. An etiologic role for TTV could not be excluded in three of the patients.
Naoumov and colleagues in London detected TTV DNA in serum of 18 (25%) of 72 patients with chronic liver disease and three (10%) of 30 healthy controls (P = 0.15). Examination of small groups of patients with liver disease of several different etiologies also found no significant difference in prevalence of detection of TTV. Sixty-three percent of TTV-positive individuals had a history of either blood transfusion or injection drug use. Fifty-eight percent of all those TTV positive had normal liver function tests.
COMMENT BY STAN DERESINSKI, MD, FACP
TTV was first described in 1997 when it was detected in the serum of a patient in Japan with post-transfusion hepatitis by representational difference analysis (the same technique that was used to initially identify kaposis sarcoma herpes virus (KSHV).1 It is reported to be a single-stranded DNA virus lacking an envelope.2
The limited data available suggest that the prevalence of TTV in the general population, in both Japan and the United Kingdom, may be as high as 10%. Evidence to date suggests that the virus is parenterally transmitted. However, the available evidence fails to demonstrate an etiologic role for this virus in causing hepatic disease. As pointed out in an accompanying editorial, TTV may be another "hepatitis" G virus (HGV)-a virus in search of a disease.3
References
1. Nishizawa T, et al. A novel DNA virus (TTV) associated with elevated transaminase levels in post-transfusion hepatitis of unknown etiology. Biochem Biophys Res Commun 1997;241:92-97.
2. Okamoto H, et al. Molecular cloning and characterization of a novel DNA virus (TTV) associated with posttransfusion hepatitis of unknown etiology. Hepatology 1998;10:1-16.
3. Cossart Y. TTV a common virus, but pathogenic? Lancet 1998;352:164.
Subscribe Now for Access
You have reached your article limit for the month. We hope you found our articles both enjoyable and insightful. For information on new subscriptions, product trials, alternative billing arrangements or group and site discounts please call 800-688-2421. We look forward to having you as a long-term member of the Relias Media community.