Detection of Epstein-Barr virus EBER sequence in post-transplant lymphoma patients with DNA dendrimers

The EBER RNAs are the most numerous viral transcripts in latently infected lymphocytes in healthy individuals and also in the tumor cells of Epstein Barr virus (EBV)-associated malignancies. A rise in EBV load in peripheral blood has been associated with the onset of post-transplant lymphoproliferative disease (PTLD) in immunocompromised patients. Treatment of PTLD with adoptive immunotherapy has made the rapid and accurate determination of EBV load essential. The relationship between EBV load and other EBV-associated malignancies, like Hodgkin's disease or AIDS-associated lymphoma, is unknown. In order to define viral load based on the number of EBV-infected cells in the peripheral blood, we developed a method which combines cellular dilution of peripheral blood mononuclear cells with the direct detection of EBER-1 RNA with DNA dendrimers. DNA dendrimers are large scaffolds of DNA which give at least a 500 1000-fold increase in detection of membrane bound nucleic acid over oilgonucleotide probes. The use of a novel class of these nucleic acid superstructures is described as a specific probe for EBER-1 detection. When two PTLD patients were analyzed for viral load with DNA dendrimers, at least one in 250000 peripheral blood mononuclear cells were shown to be infected with EBV.