DETECTION OF MULTIPLE EBNOTYPES IN INDIVIDUAL EPSTEIN-BARR-VIRUS CARRIERS FOLLOWING LYMPHOCYTE-TRANSFORMATION BY VIRUS DERIVED FROM PERIPHERAL-BLOOD AND OROPHARYNX

Transformation of a B lymphocyte into a lymphoblastoid cell line (LCL) by Epstein-Barr virus (EBV) results in the expression of EBV nuclear antigens (EBNAs) of which the size spectrum ('Ebnotype') is characteri stic for the transforming virion. Ebnotyping has been used as an epide miological tool for studies of EBV infection. We compared the occurren ce of a single and of multiple Ebnotypes, as defined by EBNAs 1, 2 and 6, in healthy and diseased EBV carriers. Cases from which two or more LCLs could be established from peripheral blood or oropharyngeal cult ures were considered informative. The frequency of multiple Ebnotypes was relatively low in healthy individuals and in patients with infecti ous mononucleosis or with haematological diseases who were awaiting a bone marrow transplant [blood, 11 of 74 patients (15 %); oropharynx, 1 2 of 49 patients (24 %)], whereas it was relatively high in recipients of bone marrow or cardiac allografts and one patient with AIDS [blood , 12 of 34 patients (35 %); oropharynx, 11 of 16 patients (69 %)]. Thr ee patterns of the simultaneous presence of multiple Ebnotypes were di stinguished. The first, most frequent, pattern observed predominantly in oropharyngeal cultures of all groups consisted of minority Ebnotype s differing from the majority type by only a single EBNA protein (usua lly EBNA I). The second, less frequent, pattern observed in the health y carriers and the (candidate) transplant recipients consisted of mino rity Ebnotypes differing from the majority type by two EBNA proteins ( mostly EBNAs 1 and 6). The third pattern, characterized by the simulta neous presence of totally different Ebnotypes, was restricted to the ( candidate) transplant recipients and the AIDS patient and was more fre quently observed in the blood than in the oropharynx. We suggest that the first two patterns result from heterologous recombinations occurri ng during viral replication at repeat sequences within the EBNA coding regions, whereas the third pattern reflects multiple infections with exogenous viruses.