<br>        Main Inclusion Criteria:<br><br>          -  Participant is 12 to 65 years old at the time of screening<br><br>          -  Participant and/or legal representative has/have provided signed informed consent<br><br>          -  Participant has severe (factor IX (FIX) level < 1%) or moderately severe (FIX level<br>             1-2%) hemophilia B (based on the one stage activated partial thromboplastin time<br>             (aPTT) assay), as tested at screening at the central laboratory<br><br>          -  Participant is previously treated with plasma-derived or recombinant FIX<br>             concentrate(s) for a minimum of 150 exposure days (EDs) (based on the participant's<br>             medical records); if a verifiable, documented history is unavailable, the participant<br>             can be enrolled if s/he has 100-150 EDs to any FIX product that are not fully<br>             documented and has participated in Study 050901 for at least 50 EDs to Immunine prior<br>             to enrollment (not valid for US and Japan).<br><br>          -  Participant has no evidence of a history of FIX inhibitors<br><br>          -  If the participant is to receive prophylactic treatment, the participant is willing to<br>             receive prophylactic treatment over a period of 6 months.<br><br>          -  If the participant is to receive on-demand treatment, the participant has =12<br>             documented bleeding episodes requiring treatment within 12 months prior to enrollment<br>             and is willing to receive on-demand treatment for the duration of this study.<br><br>        Main Exclusion Criteria:<br><br>          -  The participant has a history of FIX inhibitors with a titer =0.6 Bethesda Units (BU)<br>             (as determined by the Nijmegen modification of the Bethesda assay or the assay<br>             employed in the respective local laboratory) at any time prior to screening<br><br>          -  The participant has a detectable FIX inhibitor at screening, with a titer =0.6 BU as<br>             determined by the Nijmegen modification of the Bethesda assay in the central<br>             laboratory<br><br>          -  The participant's weight is < 35 kg or > 120 kg<br><br>          -  The participant has a history of allergic reaction, eg, anaphylaxis, following<br>             exposure to FIX concentrate(s)<br><br>          -  The participant has a known hypersensitivity to hamster proteins or recombinant furin<br>             (rFurin)<br><br>          -  The participant has ongoing or recent evidence of a thrombotic disease, fibrinolysis<br>             or disseminated intravascular coagulation (DIC)<br>