Torque Teno Virus in Children Who Underwent Orthotopic Liver Transplantation: New Insights About a Common Pathogen

Background. Torque Teno virus (TTV) is a ubiquitous infectious agent. Transplant recipients are at risk of hepatitis E virus (HEV) infection and could be vulnerable to TTV-associated adverse effects. The aim of this study was to evaluate the influence of immunosuppression and HEV infection on TTV replication and liver injury in pediatric patients after orthotopic liver transplantation (OLT). Methods. Pediatric recipients of liver transplants were classified into the following 2 groups: (1) those with normal serum aminotransferases levels and (2) those with persistently increased serum aminotransferases levels and histological features of chronic hepatitis of unknown etiology. The TTV load was assessed in 342 serum samples by use of TaqMan real-time polymerase chain reaction, along with TTV genogroups and coinfection with HEV. Results. TTV DNA was detected in 96% of tested serum samples. Viral load was significantly lower in patients with features of chronic hepatitis, of whom 78% had liver fibrosis scores of >= 2. Viral load decreased during posttransplantation follow-up. Viral load and genogroups were influenced by immunosuppression. Lower viral load was observed in patients coinfected with HEV. Conclusions. TTV infection is widespread, and its replication is closely related to immune status and viral coinfection. High TTV viremia is not associated with hepatitis after OLT, but, conversely, liver inflammatory activity impairs TTV replication.