The invention relates generally to methods of generating induced pluripotent stem cells (iPSCs) that do not contain the reprogramming vector. In some embodiments, the invention relates to inducing pluripotency in somatic cells by introducing an episomal vector(s) comprising at least one expression cassette containing reprogramming factors and/or synthetic transcription factors and a suicide gene. In some embodiments, the invention relates to inducing pluripotency in somatic cells by introducing episomal vector(s) comprising expression cassettes containing reprogramming factors and/or synthetic transcription factors and a transcriptionally regulated EBNA-1 gene. In some embodiments, the invention relates to inducing pluripotency in somatic cells by introducing episomal vector(s) comprising expression cassettes containing reprogramming factors and/or synthetic transcription factors and both a suicide gene and a transcriptionally regulated EBNA-1 gene.

Provided herein are methods for preparing and characterizing CTL cultures and preparations. Also provided herein are methods of determining the presence or absence of trace amounts of viral vectors following the preparation of CTLs.

A protein complex isolated from its natural medium and including the ZEBRA protein of sequence SEQ ID NO: 1, the isolated protein complex having the following properties: it is more stable than the ZEBRA protein, in particular it is more resistant to the action of the proteases than the ZEBRA protein, it is capable of specifically binding the AZ125 and AZ130 monoclonal antibodies, it is soluble in a body fluid, and in particular a body fluid selected from the group constituted by blood and serum,
and to its detection process and the uses of this process for the prognosis or diagnosis of lymphoproliferative episodes associated with the EBV.