Immunosuppression following bone marrow or organ transplantation, or for the treatment of autoimmune diseases, results in an increased susceptibility to infection. Viral infections are the most common because of the suppression of T-lymphocyte immune responses and patients are more prone to opportunistic pathogens. In the longer term, viral infection may also háve an impact on oncogenic potential and háve an immunomodulatory effect, which may result in further opportunistic infections.

        Key words: viral infection, transplantation, immunodeficiencies.