The Perioperative Lung Transplant Virome

Primary graft dysfunction (PGD) is a principal cause of early morbidity and mortality after lung transplantation, but its pathogenic mechanisms are not fully clarified. Thus far, studies using standard clinical assays have not linked microbial factors to PGD. We previously used comprehensive metagenomic methods to characterize viruses in lung allografts >1 month post-transplant and found that levels of Anellovirus, mainly Torque teno viruses (TTV), were significantly higher than in non-transplant healthy controls. Here we used quantitative PCR to analyze TTV and shotgun metagenomics to characterize full viral communities in acellular bronchoalveolar lavage from donor organs and post-reperfusion allografts in PGD and non-PGD lung transplant recipient pairs. Unexpectedly, TTV DNA levels were 100-fold elevated in donor lungs compared with healthy adults (p=0.0026). Although absolute TTV levels did not differ by PGD status, PGD cases showed a smaller increase in TTV levels from pre- to post-transplant than did control recipients (p=0.041). Metagenomic sequencing revealed mainly TTV and bacteriophages of respiratory tract bacteria, but no viral taxa distinguished PGD cases from controls. These findings suggest that conditions associated with brain death promote TTV replication, and that greater immune activation or tissue injury associated with PGD may restrict TTV abundance in the lung.