The purpose of this trial is to determine safety and efficacy of 16 weeks treatment with thymosin alpha 1 given at 1.6 mg dose once daily by subcutaneous injection in adult patients with hematological undergone allogenic bone marrow transplantation and CMV positive. The efficacy will be explored assessing the ability of thymosin alpha1 to prevent the infection complications.

This is an open label, monocenter, explorative study . A total of 9 patients will be included in the study in three sequential cohort of 3 patients each. Patients will enter into the study after meeting the inclusion and exclusion criteria and signing the Informed Consent Form. The first three patients will be treated for 16 weeks starting 40 days after transplantation; if all three patients will complete the treatment period without any serious treatment related adverse event then the recruitment of second cohort of patients will be opened and patients treated starting from 20 days after transplantation. The same procedure will be applied for the third cohort of patients starting treatment from day of transplantation.