Torquetenovirus viremia for early prediction of graft rejection after kidney transplantation

Abstract

Objectives: New biomarkers reflecting the degree of immunosuppression in transplant recipients are needed to provide an optimal personalized balance between rejection and infection risks.

Methods: For this purpose, we investigated TTV viremia dynamics in 66 kidney transplant recipients followed up for two years after transplantation, in relation to BK virus infection and graft rejection.

Results: After transplantation, TTV viremia rose by ≥2 log₁₀ copies/mL from baseline to month 3, then declined by ≥1 log₁₀ copies/mL thereafter. Higher TTV viremia was associated with recipients of a deceased donor, a lower count of CD8+ T cells and a higher BKV viremia. Importantly, TTV loads were significantly lower in KTR who would later display graft rejection; indeed, patients with TTV viremia lower than 3.4 log₁₀ copies/mL at transplantation or lower than 4.2 log₁₀ copies/mL at month 1 had a higher risk of developing graft rejection in the two following years (hazard ratio (HR) at D0 = 7.30, p = 0.0007 and HR at M1 = 6.16, p = 0.001).

Conclusions: TTV viremia measurement at early times post transplantation predicts graft rejection and would represent a useful tool to improve kidney transplant monitoring.

Keywords: BK virus; Biomarker; Graft rejection; Torquetenovirus.