*Purpose: The apathogenic Torque Teno Virus (TTV) is highly prevalent among solid organ transplant recipients and mirrors the immunocompetence of its host. qPCR based measurement of TTV levels in the peripheral blood is a promising tool on the way towards holistic immunosuppression, but requires out-patient clinic visits for peripheral blood sampling on a regular basis in order to adequately depict TTV kinetics over time. The Mitra® Cartridge micro-sampling device (Neoteryx, California, US) is a novel sampling technique for the remote collection of fixed volume capillary blood and may allow for individualised TTV measurement delays independent of routine visits.

*Methods: TTV DNA load was repeatedly assessed in eleven patients after lung transplantation from EDTA-plasma (200µl) obtained by peripheral blood sampling and from dried blood (10µl) collected by capillary blood microsampling at the same time using the Mitra® Cartridge device. Dried blood was stored 2 days at room temperature prior to analyses in order to mimic a routine setting of remote blood collection. Samples were analysed in two independent runs of real time-polymerase chain reaction using the same positive and negative controls.

*Results: 11 stable long-term transplant recipients (39 months (median) after transplantation) had comparable median log levels of TTV DNA in plasma (7.4 log copies/ml) compared to capillary blood (8.0 log copies/ml). Pearson correlation presented that there was a significantly positive correlation between EDTA-Plasma and capillary levels (r=0.96, p<0.001) (Fig.1).

*Conclusions: This prove-of-concept study reveals a high correlation of TTV DNA load measured in plasma compared to capillary blood in patients after solid organ transplantation. Volumetric absorptive microsampling may be an adequate device to measure TTV levels for remote immunomonitoring in an outpatient transplant recipient cohort, but larger sample sizes will be needed to confirm our preliminary data.

« Back to 2020 American Transplant Congress