Complementation of adenovirus early region 1a and 2a mutants by Epstein-Barr virus immortalized lymphoblastoid cell...

Human B-lymphocytes may be infected by both adenoviruses and the Epstein-Barr virus (EBV). Some of the immediate early and early proteins in the two viruses are similar in function even though their primary structures are different. As these viruses might infect the same B-cells in man, we asked if complementation could take place. The adenovirus mutant H5ts125 has a thermolabile DNA-binding protein and is defective in DNA replication at 39 degrees. Several EBV-transformed human lymphoblastoid cell lines and a tamarin cell line B95-8 were infected with H5ts125 and incubated at either the nonpermissive or the permissive temperatures. Adenoviral DNA replication and assembly of new virions were observed at both temperatures, suggesting complementation by the resident EBV gene products. The adenovirus E1a region is deleted in the mutant d1312. Complementation of this mutant was only obtained in the EBV producer B95-8 cells. Immortalization by EBV was apparently not sufficient for effective complementation. This supports an earlier observation that one of the EBV early proteins (MS-EA) behaves like adenovirus E1a and can transactivate the E4 promoter in a CAT assay. The complementation of mutant adenoviruses in EBV-transformed lymphocytes may help the rescue of new adenovirus serotypes in immunosuppressed patients.