Assessment of prevalence and load of torquetenovirus viraemia in a large cohort of healthy blood donors

Objectives: Torquetenovirus (TTV) is an emerging marker of functional immune competence with the potential to predict transplant-related adverse events. A large-scale epidemiological study was performed to understand how basal values vary in healthy individuals according to age and gender. Methods: We tested plasma from 1017 healthy blood donors aged 18-69 years. The presence and load of TTV were determined by a real-time PCR assay. A sub-cohort of 384 donors was tested for anti-cytomegalovirus IgG antibodies, and 100 participants were also tested for TTV viraemia on a paired whole blood sample. Results: The overall prevalence of TTV was 65% (657/1017) with a mean (+/- SD) growth of 5 +/- 4% every 10 years of age increase, but stably higher in males (465/690, 67%) than in females (192/327, 59%). Mean (+/- SD) TTV load was 2.3 +/- 0.7 Log copies/mL with no sex difference. TTV viraemia showed modest increases along 10-year age intervals (mean +/- SD: 0.3 +/- 0.1). TTV viraemia in donors sampled 2 years later remained stable (mean +/- SD: 2.3 +/- 0.8 versus 2.2 +/- 0.7 Log copies between samples). Twenty-six per cent (9/34) of blood donors with Try-negative plasma scored positive when whole blood was tested, and the donors with positive plasma showed a mean (+/- SD) 1.4 +/- 0.5 Log increase in copy numbers when whole blood was tested. Conclusions: This study establishes the mean value of Try viraemia in plasma in healthy blood donors and suggests that ageing causes only minimal increases in TTV viraemia. (C) 2020 European Society of Clinical Microbiology and Infectious Diseases. Published by Elsevier Ltd. All rights reserved.