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Abstract: FR-PO785

Torque Teno Virus Might Be a Better Predictor of Immunosuppressive Burden in BK Viremia Post Renal Transplant

Session Information

Category: Transplantation

  • 2002 Transplantation: Clinical

Authors

  • Chakraborty, Ramyangshu, The Royal London Hospital, London, London, United Kingdom
  • Bible, Jon, The Royal London Hospital, London, London, United Kingdom
  • Allan, Michelle Elizabeth, The Royal London Hospital, London, London, United Kingdom
  • Kashem, Tasnuva Sarah, The Royal London Hospital, London, London, United Kingdom
  • Fan, Stanley, The Royal London Hospital, London, London, United Kingdom
  • Mccafferty, Kieran, The Royal London Hospital, London, London, United Kingdom
  • Cutino Moguel, Teresa Maria, The Royal London Hospital, London, London, United Kingdom
  • Yaqoob, Muhammad Magdi, The Royal London Hospital, London, London, United Kingdom
Background

The ubiquitous Torque Teno DNA virus (TTV) promises increased accuracy in IS burden prediction. We examined the presence and change in TTV titres in patients with BK viremia in preparation for a prospective observational study evaluating TTV as a measure of IS burden.

Methods

Stored blood samples and electronic records from 20 renal transplant recipients from 2017-19 at a tertiary care centre were included in the analysis. All received standardised tacrolimus based IS and experienced a clinically significant episode of BK viremia which responded to standard of care cessation of mycophenolate (MMF).
BK & TTV titres, 30-day average tacrolimus concentration, antiproliferative & prednisolone doses were collected at four-time points: the last negative BK PCR; the onset of viremia; the peak BK titre & BK titre <500 copies.
TTV PCR was performed on DNA extracted from frozen plasma. Multivariable linear regression analysis was performed in R to assess the relationship between TTV and other variables.

Results

TTV DNA was detectable at 78 out of 80 time points. The mean TTV titre at the 4 time points were 5.0 (2.07), 5.5 (1.74), 6.2 (2.14) & 4.6 (1.27) log copies respectively. In the linear model, log-transformed BK virus titre was strongly associated with TTV titres once adjusted for tacrolimus concentration: every 1 log rise in TTV titre led to 0.6 (0.17) log copies increase in BKV titre (p <0.001). The tight relationship between BKV and tacrolimus concentration (p <0.001) disappeared when TTV titre was added as a predictor variable, implying the superiority of TTV to tacrolimus concentration as a predictor for BK viral load. Changes in MMF or prednisolone dose did not predict linear changes in BKV titres.
Five patients had graft loss within the follow-up period (mean 2.8 years). All had low (p<0.05) TTV titres indicating suboptimal IS burden. There was no relationship between rejection (n=5) or de novo DSA (n=3) with TTV titre in this cohort.

Conclusion

This pilot study suggests that TTV is detectable in most instances post-transplant. TTV titres indicate the effect of IS changes on BK titre independently. An ongoing adequately powered prospective study will further assess the relationship between TTV titres & post-transplant immunological events.