Quantification of Torque Teno Virus Viremia as a Prospective Biomarker for Infectious Disease in Kidney Allograft Recipients

BACKGROUND: Drug-induced immunosuppression following kidney transplantation is crucial to prevent allograft rejection, but increases risk for infectious disease. Tailoring of drug dosing to prevent both rejection and infection is greatly desirable. The apathogenic and ubiquitous torque teno virus (TTV) reflects immunocompetence of the host and might be a potential candidate for immunologic monitoring. METHODS: To assess TTV as an infection biomarker, virus load was prospectively quantified in peripheral blood of 169 consecutive renal allograft recipients at the Medical University Vienna. RESULTS: Patients with infection showed higher TTV levels compared to patients without infection (4.2 × 10(8) copies/mL [interquartile range, IQR, 2.7 × 10(7)–1.9 × 10(9)] vs 2.9 × 10(7) [IQR 1.0 × 10(6)–7.2 × 10(8)]; P = .006). Differences in TTV load became evident almost 3 months before infection (median 77 days, IQR 19–98). Each log level of TTV copies/mL increased the odds ratio for infection by 23% (95% confidence interval 1.04–1.45; P = .014). TTV >3.1 × 10(9) copies/mL corresponded to 90% sensitivity to predict infections. Logistic regression demonstrated independent association between TTV levels and infection. CONCLUSIONS: TTV quantification predicts infection after kidney transplantation and might be a potential tool to tailor immunosuppressive drug therapy.