Bronchiolitis obliterans (BO) is the well-known manifestation of the chronic pulmonary graft-versus-host disease(GVHD) after allogeneic hematopoietic stem cell transplantation (HSCT). The pathophysiology of BO is, however, poorly known. The available data strongly support the role of respiratory viruses, in particular paramyxoviruses (parainfluenzae virus (PIV), respiratory syncytial virus, metapneumovirus). It is likely that the alloimmune response triggered by the respiratory virus is inadequate and leads to the peribronchiolar fibrotic process. The objective is to analyze the kinetics of profiles of the blood and respiratory host responses resulting from a high or low parainfluenza respiratory infection, in order to evaluate if the occurrence of a BO is associated with a specific signature We will evaluate the predictive signature of a BO after a parainfluenza virus infection by characterizing the differences between the patients evolving and those not evolving to a BO at 2 months after the infection.

Inclusion Criteria :

• Adults having received a hematopoietic stem cell transplantation for less than two years
• Availability of respiratory function tests prior to infection
• Presence of PIV respiratory infection documented by identification of the virus by PCR in the upper and/or lower respiratory tract
• Symptoms of respiratory infection ≤ 5 days
• Signed informed consent

Exclusion Criteria:

• Presence of a respiratory virus infection other than PIV
• Viral respiratory co-infections
• Bacterial or fungal respiratory infections
• Treatment with ribavirin, oseltamivir or any other antiviral with activity against respiratory viruses
• Patient not affiliated or beneficiary of a social security system
• Patient deprived of liberty or protected
• Pregnant or breastfeeding woman

Adult recipients of allogeneic HSCT with PIV pulmonary infection