title: Pre-transplant plasma Torque Teno virus load and increase dynamics after lung transplantation.
abstract: BACKGROUND
  The human Torque Teno virus (TTV) causes persistent viremia in most immunocompetent individuals. Elevated TTV levels are observed after solid organ transplantation and are related to the extent of immunosuppression especially during the phase of maintenance immunosuppression. However, the extent to which the TTV increase in the early phase post-transplantation is associated with the patient's immunosuppressive state is unclear.
  
  
  OBJECTIVE
  In this study, we assessed the TTV increase dynamics in detail during the first three months after lung transplantation under a defined immunosuppressive regimen and in relation to the pre-transplant TTV level.
  
  
  METHODS
  Forty-six lung transplant recipients (LTRs) were included in this prospective longitudinal study. All received alemtuzumab induction combined with tacrolimus and corticosteroids immunosuppressive therapy. Plasma TTV DNA was monitored before transplantation and regularly within the first three months post-transplantation (n = 320 samples; mean sampling interval: 12.2 days).
  
  
  RESULTS
  In 43/46 LTRs (93%), TTV DNA was detectable before transplantation (median 4.4 log10 copies/mL; range: 2.0-6.4). All 46 LTRs showed a TTV increase post-transplantation, which followed a sigmoidal-shaped curve before the median peak level of 9.4 log10 copies/mL (range: 7.6-10.7) was reached at a median of day 67 (range: 41-92). The individual TTV DNA doubling times (range: 1.4-20.1 days) significantly correlated with the pre-transplant TTV levels calculated over 30 or 60 days post-transplantation (r = 0.61, 0.54, respectively; both P < 0.001), but did not correlate with the mean tacrolimus blood levels. Pre-transplant TTV levels were not associated with time and level of the patients' post-transplant TTV peak load.
  
  
  CONCLUSIONS
  The TTV level may be used to mirror the state of immunosuppression only after the patients' initial peak TTV level is reached.
authors.affiliation: Department of Virology, Medical University of Vienna, Vienna, Austria.
authors.forename: Irene
authors.initials: I
authors.lastname: Görzer
authors.affiliation: Division of Thoracic Surgery, Medical University of Vienna, Vienna, Austria.
authors.forename: Peter
authors.initials: P
authors.lastname: Jaksch
authors.affiliation: Institute of Environmental Health, Medical University of Vienna, Vienna, Austria.
authors.forename: Michael
authors.initials: M
authors.lastname: Kundi
authors.affiliation: Department of Virology, Medical University of Vienna, Vienna, Austria.
authors.forename: Tamara
authors.initials: T
authors.lastname: Seitz
authors.affiliation: Division of Thoracic Surgery, Medical University of Vienna, Vienna, Austria.
authors.forename: Walter
authors.initials: W
authors.lastname: Klepetko
authors.affiliation: Department of Virology, Medical University of Vienna, Vienna, Austria.
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Puchhammer-Stöckl
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D007165:Immunosuppression Therapy / Q000009:adverse effects; D007700:Kinetics; D016040:Lung Transplantation / Q000009:adverse effects*; D008297:Male; D008875:Middle Aged; D010949:Plasma / Q000187:drug effects / Q000821:virology*; D022783:Torque teno virus / Q000502:physiology*; D019562:Viral Load / Q000187:drug effects; D055815:Young Adult