Treatment of resistant viral infections after allogeneic hematopoietic stem cell transplantation using virus-specific T cells

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is widely used in the treatment of malignant and non-malignant diseases. Patients treated with allo-HSCT receive immunosuppression, which lowers the organism's immune response. This leaves a significant period during which the host is seriously deficient in T cell immunity. Viral infections are therefore one of the major causes of morbidity and mortality in these patients. Available prophylactic and preventive antiviral pharmacotherapies are often insufficient or limited due to toxicity, ineffectiveness, or the development of drug resistance, and additionally do not provide long-term protection or immunological memory. A current extension of virostatic agents is the transplantation of antiviral immunity through adoptive transfer of virus-specific T cells (VSTs) against ADV, CMV, or EBV. Strategies that accelerate pathogen-specific immunity and T-cell regeneration may complement or replace available treatments.