Detection of human herpesvirus 6 sequences in lymphoma tissues by immunohistochemistry and polymerase chain reactions

We have analyzed one Hodgkin's and six non-Hodgkin's lymphomas for the presence of human herpesvirus 6 (HHV-6) and Epstein-Barr virus (EBV) DNA by polymerase chain reaction (PCR) and antigens by immunohistochemistry. A large cell B-cell lymphoma and a T-cell lymphoma were positive for HHV-6 antigens by immunohistochemistry. Using PCR primers from the HHV-6 ZVH14 transforming DNA segment, all seven tumors were positive. EBV DNA was not detected by PCR using sequences from EBV internal repeat-3 region as primers. The data suggest an etiologic involvement of HHV-6 in some human lymphomas. Although all seven of the lymphoma tissues examined contained HHV-6 DNA, expression of HHV-6 antigens was observed in only two cases, suggesting that expression of proteins was not required for transformation.