Detection of a nuclear antigen 2 (EBNA2)-variant Epstein-Barr virus strain in two siblings with fatal lymphoproliferative disease.

An EBV type 1 variant strain was detected in two Turkish siblings (boy and girl), who both suffered and died from similar progressive Epstein-Barr virus (EBV)-associated lymphoproliferative disease. Molecular characterisation of this EBV isolate revealed a 51bp-deletion and six nucleotide changes within the Epstein-Barr nuclear antigen 2 (EBNA2). Both isolates contained EBV type 2 sequences in the Epstein-Barr virus-encoded small RNAs (EBER), which are 40 kb proximal to EBNA2. Sequencing of the EBV isolates in a region of Epstein-Barr nuclear antigen 3 (EBNA3a), which is 40 kb distal to EBNA2, revealed the normal EBV type 1 sequence of laboratory strain B95-8. This EBV isolate may represent a distinct wild type EBV strain with altered biological properties. It is suggested that this EBNA2-variant strain may be responsible at least in part for the severe clinical course in both affected children.