Torque Teno Virus (TTV): molecular virology and clinical implications

Abstract

This chapter focuses on the molecular virology of torque teno virus (TTV), and provides an overview of the clinical significance of TTV infections in humans. TTV is a novel DNA virus unrelated to the known human viruses isolated from the serum of a patient with post-transfusion acute hepatitis of unknown etiology. Taxonomic nomenclatures for TTV and TTV-like mini virus have been proposed by the ICTV circoviridae study group, and they are designated as TTV and torque teno mini virus (TTMV), respectively. TTV and TTMV are classified into a novel floating genus, the anellovirus genus that has not yet been assigned to a family. The natural history and pathogenic potential of TTV are currently under intensive investigation. Although the precise relationship between TTV infection and viral hepatitis remains to be established, it is likely that certain genotypes of TTV or some strains of TTV cause hepatitis in some clinical and epidemiological settings. Moreover, detailed cross-sectional and longitudinal studies are required to address the exact role of TTV in children and adults with cryptogenic liver disease or other diseases that are currently of unknown etiology, with regard to the genotypes and viral load of TTV.