Dynamics of Human Anelloviruses in Plasma and Clinical Outcomes Following Kidney Transplantation

Torque teno virus, the major member of the genus Alphatorquevirus , is an emerging biomarker of the net state of immunosuppression after kidney transplantation. Genetic diversity constitutes a main feature of the Anelloviridae family, although its posttransplant dynamics and clinical correlates are largely unknown.

The relative abundance of Alphatorquevirus , Betatorquevirus , and Gammatorquevirus genera was investigated by high-throughput sequencing in plasma specimens obtained at various points during the first posttransplant year (n = 91 recipients). Total loads of all members of the Anelloviridae family were also quantified by an "in-house" polymerase chain reaction assay targeting conserved DNA sequences (n = 195 recipients). In addition to viral kinetics, clinical study outcomes included serious infection, immunosuppression-related adverse event (opportunistic infection and cancer)' and acute rejection.

Alphatorquevirus DNA was detected in all patients at every point, with an increase from pretransplantation to month 1. A variable proportion of recipients had detectable Betatorquevirus and Gammatorquevirus at lower frequencies. At least 1 change in the predominant genus (mainly as early transition to Alphatorquevirus predominance) was shown in 35.6% of evaluable patients. Total anelloviruses DNA levels increased from baseline to month 1, to peak by month 3 and decrease thereafter, and were higher in patients treated with T-cell depleting agents. There was a significant albeit weak-to-moderate correlation between total anelloviruses and TTV DNA levels. No associations were found between the predominant Anelloviridae genus or total anelloviruses DNA levels and clinical outcomes.

Our study provides novel insight into the evolution of the anellome after kidney transplantation.