2 SHORT AUTOEPITOPES ON THE NUCLEAR DOT ANTIGEN ARE SIMILAR TO EPITOPES ENCODED BY THE EPSTEIN-BARR-VIRUS

To understand the relationship between antibodies present in patients with anti-nuclear dot (ND) autoimmune disease and the proteins they re cognize, epitopes that react with the autoantibodies were mapped. A pa nel of fusion proteins containing different portions of the ND protein were overproduced in Escherichia coli. Immunoblot analysis with anti- ND antibodies revealed that most (10 of 12) sera recognize two major a utoepitopes,that are each a maximum of 8 amino acids long. The other t wo sera recognize one of the two epitopes. In addition to the short li near autoepitopes, a conformational epitope appears to be present on t he ND antigen. Each of the two linear epitope sequences shares sequenc e similarities with those of several viral proteins found in the datab ases. Furthermore, two fusion proteins containing short Epstein-Barr v irus (EBV) protein sequences that are similar to the ND epitopes were recognized by the human autoimmune sera, indicating that the autoepito pes are present in EBV protein sequences. Our results are consistent w ith the hypothesis that ND autoimmune disease might be associated with EBV infections.