BK virus (BKV) is a ubiquitous virus that infects more than 80% of the population. In case of immunosuppression, BKV can replicate and induce nephropathies in renal transplant recipients or haemorrhagic cystitis in bone marrow transplant recipients. The disruption of the balance between BKV replication and immune control is considered the key element in the development of these pathologies. During lung transplantation, patients undergo intense immunosuppression that favors the reactivation of persistent viruses such as EBV, CMV and probably BKV. Although the data on EBV and CMV reactivation are very clear and allow optimal management, the prevalence of BKV replication and its clinical impact in lung transplant recipients remains unknown at this time.

The aim of this study is to know the incidence and clinical impact of BKV replication in lung transplant recipients. Moreover, the results will help to better understand the interaction between the virus and his host, with a focus on the humoral and cellular immune response against BKV. The results could possibly enable to define predictive markers of BKV replication and of its evolution.

Inclusion criteria:

• Lung transplant recipients in Strasbourg University Hospital between 30 June 2018 and 31 December 2022
• Male or female patients, age over 18 years
• Patient having provided informed written consent to take part in the study
• Patient affiliated to Social Security

Exclusion criteria:

• Patient deprived of liberty, by judicial or administrative decision
• Patient under legal guardianship
• Impossibility to give complete information about this study to the patient

Lung transplant recipients between 30 June 2018 and 31 December 2022 at the University Hospital of Strasbourg