Editorial
Copyright ©The Author(s) 2020. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Transplant. Nov 28, 2020; 10(11): 291-296
Published online Nov 28, 2020. doi: 10.5500/wjt.v10.i11.291
Torque teno virus in liver diseases and after liver transplantation
Anna Mrzljak, Tatjana Vilibic-Cavlek
Anna Mrzljak, Department of Medicine, Merkur University Hospital, School of Medicine, University of Zagreb, Zagreb 10000, Croatia
Tatjana Vilibic-Cavlek, Department of Virology, Croatian Institute of Public Health; School of Medicine, University of Zagreb, Zagreb 10000, Croatia
Author contributions: Mrzljak A and Vilibic-Cavlek T conceived and designed the study and were involved in drafting and revising the manuscript critically; Both authors approved the final manuscript.
Conflict-of-interest statement: The authors declare they have no potential conflicts of interest.
Open-Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/Licenses/by-nc/4.0/
Corresponding author: Anna Mrzljak, MD, PhD, Associate Professor, Department of Medicine, Merkur University Hospital, School of Medicine, University of Zagreb, Zajčeva 19, Zagreb 10000, Croatia. anna.mrzljak@gmail.com
Received: May 16, 2020
Peer-review started: May 16, 2020
First decision: September 18, 2020
Revised: September 22, 2020
Accepted: October 9, 2020
Article in press: October 9, 2020
Published online: November 28, 2020
Processing time: 190 Days and 18.7 Hours
Abstract

Torque teno virus (TTV) has been proposed as a surrogate biomarker for immune monitoring in different patient cohorts. Historically, TTV has been associated with different liver diseases such as post-transfusion hepatitis, hepatitis B, and hepatitis C, but the virus's pathogenicity is controversial. TTV is a ubiquitous DNA virus, highly prevalent and mostly indolent in the general population. Thus, TTV viral load is more relevant than prevalence to understand TTV infection. In the context of liver transplantation, TTV viral load is modulated by the immune, viral, and inflammatory status. After liver transplantation, the TTV viral load positively correlates with the intensity of immunosuppression (IS), and low TTV viral burden is a predictor of acute rejection episodes, making it an attractive marker for the efficacy of IS. However, the TTV role as a single or a panel biomarker needs to be evaluated in further independent prospective trails.

Keywords: Torque teno virus; Solid-organ transplantation; Biomarker; Liver disease; Liver transplant; Immune system

Core Tip: Torque teno virus (TTV) is a ubiquitous, highly prevalent, and mostly indolent DNA virus in the general population. Historically, it has been associated with different liver diseases, but the virus's pathogenicity is controversial. TTV viral load is modulated by immune, viral, and inflammatory status. TTV viral load positively correlates with the intensity of immunosuppression, making it an attractive surrogate biomarker for immune monitoring in different patient cohorts, including liver transplant recipients. However, the TTV role as a single or a panel biomarker needs to be evaluated in further trials.