Torque Teno Virus DNA Load in Blood as an Immune Status Biomarker in Adult Hematological Patients: The State of the Art and Future Prospects

Abstract

A solid body of scientific evidence supports the assumption that Torque teno virus (TTV) DNA load in the blood compartment may behave as a biomarker of immunosuppression in solid organ transplant recipients; in this clinical setting, high or increasing TTV DNA levels precede the occurrence of infectious complications, whereas the opposite anticipates the development of acute rejection. The potential clinical value of the TTV DNA load in blood to infer the risk of opportunistic viral infection or immune-related (i.e., graft vs. host disease) clinical events in the hematological patient, if any, remains to be determined. In fact, contradictory data have been published on this matter in the allo-SCT setting. Studies addressing this topic, which we review and discuss herein, are highly heterogeneous as regards design, patient characteristics, time points selected for TTV DNA load monitoring, and PCR assays used for TTV DNA quantification. Moreover, clinical outcomes are often poorly defined. Prospective, ideally multicenter, and sufficiently powered studies with well-defined clinical outcomes are warranted to elucidate whether TTV DNA load monitoring in blood may be of any clinical value in the management of hematological patients.

Torquetenovirus Viremia Quantification Using Real-Time PCR Developed on a Fully Automated, Random-Access Platform

“…Each of these viruses consists of numerous species and strains. The recent evidence that TTV represents the most abundant component of the human virome and establishes a highly successful interaction with the infected host [ 1 ] has highlighted the importance of using the monitoring of TTV viremia as a biomarker of functional immune competence [ 9 , 10 , 11 , 12 , 13 , 14 ]. Thus, the use of diagnostic tests that can be performed for rapid and sensitive quantification of TTV is of utmost importance for follow-up monitoring and therapy decisions in several patient settings, notably solid organ transplant recipients [ 15 , 16 ].…”

The Emerging Tool of the Human Anellovirome

“…In conclusion, this Special Issue hosts a review of TTV kinetics in hematological oncology patients—one of the very first cohorts where the role of TTV as a surrogate marker of functional immune competence first emerged [ 9 ]. This review highlights its heterogeneity in design, patient characteristics, time points selected for TTV DNA load monitoring, PCR assays used for TTV DNA quantification, and clinical outcomes, which are often poorly defined.…”