In situ hybridization for the detection of cytomegalovirus in blood or bone marrow leucocytes after allogeneic bone marrow transplantation.

We report a study of CMV detection by a nonradioactive in situ hybridization (ISH) technique using a biotinylated CMV-DNA probe. The method was applied to blood and bone marrow cells and its results were compared with those of other currently used techniques. First, we analysed peripheral leucocytes on blood donors, and, after comparison with PCR, we obtained 75% sensitivity and 87% specificity rates. We then studied four BMT recipients during the first 105 d post-transplant. A positive signal was detected as a predominantly nuclear staining. The detection of an ISH-positive signal occurred at least 8 d before CMV isolation from viral culture. The number of positive cells was variable according to the patients' clinical evolution, showing a dramatic increase of labelled cells in viraemic patients and then a decrease until complete disappearance of labelled cells when an efficient anti-viral treatment was initiated. This study suggests that the detection of CMV-DNA by ISH performed on peripheral leucocytes is a valuable tool for the early diagnosis of CMV infection and could lead to the initiation of optimal ganciclovir treatment.