Use of at least one biomarker for the in vitro prognosis or diagnosis of lymphoproliferative episodes associated with the epstein-barr virus (ebv)

Protein complex isolated from its natural medium and comprising the ZEBRA protein of sequence SEQ ID NO:

• 1, said isolated protein complex having the following properties:
• it is more stable than the ZEBRA protein, in particular it is more resistant to the action of the proteases than the ZEBRA protein,
• it is capable of specifically binding the AZ125 and AZ130 monoclonal antibodies,
• it is soluble in a body fluid originating from patients who are seropositive for EBV, and in particular a body fluid selected from the group constituted by blood and serum,
• it is in a form circulating in said body fluid originating from patients who are seropositive for EBV,
• it can be assayed directly in said body fluid originating from patients who are seropositive for EBV.