To evaluate the safety,tolerability and antiviral activitity of ALN-RSV01 in RSV infected lung transplant patients

Inclusion Criteria:

• Single or bilateral lung transplant recipients
• Confirmed RSV infection
• Greater than 90 days post current lung transplant
• Rejection free for a minimum of 1 month

Exclusion Criteria:

• Antimicrobial therapy for known viral, bacterial, or fungal respiratory co-infection at the time of diagnosis
• Bronchiolitis obliterans syndrome (BOS) Grade 3 or any state BOS with FEV1 that has not been stable for at least 3 months
• Use of alemtuzumab within 9 months prior to screening; anti-thymocyte globulin(ATG) or thymoglobulin within 3 months of screening: concurrent use of >= 0.3 mg/kg/day prednisone or equivalent as maintenance therapy
• active treament for acute graft rejection