Identification and expression of a nuclear antigen from the genomic region of the Jijoye strain of Epstein-Barr virus that is missing in its nonimmortalizing deletion mutant, P3HR-1.

An Epstein-Barr virus (EBV) deletion mutant, HR-1, cannot immortalize lymphocytes. HR-1 was derived from a virus strain, Jijoye, that is immortalization competent. Using human antiserum from certain patients with chronic active EBV infection, we have identified in Jijoye cells a protein of apparent mass of 78-80 kDa that is missing in cells with the HR-1 genome. A protein of identical size and antigenicity has been stably expressed in mouse LTK- cells by gene transfer with cloned Jijoye EBV DNA that encompasses the deletion in the HR-1 genome. The expressed product is a nuclear neoantigen. The polypeptide we have identified is likely to be essential in the immortalization process.