A search for the possible origin of competing T-helper cells was undertaken with the BLAST analytical program [42, 43] . Sequence homologies were evident over the entire expanded EBNA1 epitope with proteins from CP and HHV-6 ( Table 1 ). This possible involvement of HHV-6 and CP in T cell competition is supported by the observation that the targets of T-and B-cells which have been found to be MS-associated by systematic studies [34, 35] also have homologies in HHV-6 and CP ( Table 2) .