Hensold, J. O., Stratton, C. A., Barth, D. & Galson, D. L. (1996). Expression of the transcription factor, Spi-1 (PU.1), in differentiating murine erythroleukemia cells Is regulated post-transcriptionally. Evidence for differential stability of transcription factor mRNAs following inducer exposure. J Biol Chem 271, 3385–3391. Houff, S. A., Major, E. O., Katz, D. A., Kufta, C. V., Sever, J. L., Pittaluga, S., Roberts, J. R., Gitt, J., Saini, N. & Lux, W. (1988). Involvement of JC virus-infected mononuclear cells from the bone marrow and spleen in the pathogenesis of progressive multifocal leukoencephalopathy. N Engl J Med 318, 301–305. Iida, T., Kitamura, T., Guo, J., Taguchi, F., Aso, Y., Nagashima, K. & Yogo, Y. (1993). Origin of JC polyomavirus variants associated with progressive multifocal leukoencephalopathy. Proc Natl Acad Sci U S A 90, 5062–5065. Jensen, P. N. & Major, E. O. (1999). Viral variant nucleotide sequences help expose leukocytic positioning in the JC virus pathway to the CNS. J Leukoc Biol 65, 428–438. Kenney, S., Natarajan, V. & Salzman, N. P. (1986a). Mapping 59 termini of JC virus late RNA. J Virol 58, 216–219. Kenney, S., Natarajan, V., Selzer, G. & Salzman, N. P. (1986b). Mapping 59 termini of JC virus early RNAs. J Virol 58, 651–654. Kerr, D., Chang, C. F., Chen, N., Gallia, G., Raj, G., Schwartz, B. & Khalili, K. (1994). Transcription of a human neurotropic virus promoter in glial cells: effect of YB-1 on expression of the JC virus late gene. J Virol 68, 7637–7643. Khalili, K., Khoury, G. & Brady, J. (1986). Spacing between simian virus 40 early transcriptional control sequences is important for regulation of early RNA synthesis and gene expression. J Virol 60, 935–942. Kim, J., Woolridge, S., Biffi, R., Borghi, E., Lassak, A., Ferrante, P., Amini, S., Khalili, K. & Safak, M. (2003). Members of the AP-1 family, c-Jun and c-Fos, functionally interact with JC virus early regulatory protein large T antigen. J Virol 77, 5241–5252. Krebs, C. J., McAvoy, M. T. & Kumar, G. (1995). The JC virus minimal core promoter is glial cell specific in vivo. J Virol 69, 2434–2442. Kumar, K. U., Pater, A. & Pater, M. M. (1993). Human JC virus perfect palindromic nuclear factor 1-binding sequences important for glial cell-specific expression in differentiating embryonal carcinoma cells. J Virol 67, 572–576. Kumar, K. U., Devireddy, L. R., Tang, S. C., Pater, A. & Pater, M. M. (1996). Human JC virus nuclear factor 1 binding motifs and large tumor antigen region required for transactivation of late promoter. J Neurochem 67, 473–481. Laux, G., Dugrillon, F., Eckert, C., Adam, B., Zimber-Strobl, U. & Bornkamm, G. W. (1994). Identification and characterization of an Epstein–Barr virus nuclear antigen 2-responsive cis element in the bidirectional promoter region of latent membrane protein and terminal protein 2 genes. J Virol 68, 6947–6958. Lindberg, R. L., Achtnichts, L., Hoffmann, F., Kuhle, J. & Kappos, L. (2008). Natalizumab alters transcriptional expression profiles of blood cell subpopulations of multiple sclerosis patients. J Neuroimmunol 194, 153–164. Lynch, K. J. & Frisque, R. J. (1990). Identification of critical elements within the JC virus DNA replication origin. J Virol 64, 5812–5822. Major, E. O. (2009). Reemergence of PML in natalizumab-treated patients – new cases, same concerns. N Engl J Med 361, 1041–1043. Major, E. O. (2010). Progressive multifocal leukoencephalopathy in patients on immunomodulatory therapies. Annu Rev Med 61, 35–47. Major, E. O., Vacante, D. A., Traub, R. G., London, W. T. & Sever, J. L. (1987). Owl monkey astrocytoma cells in culture spontaneously http://vir.sgmjournals.org Spi-B binds JCV sequence and supports viral activity produce infectious JC virus which demonstrates altered biological properties. J Virol 61, 1435–1441. Mao, C., Ray-Gallet, D., Tavitian, A. & Moreau-Gachelin, F. (1996). Differential phosphorylations of Spi-B and Spi-1 transcription factors. Oncogene 12, 863–873. Marshall, L. J. & Major, E. O. (2010). Molecular regulation of JC virus tropism: insights into potential therapeutic targets for progressive multifocal leukoencephalopathy. J Neuroimmune Pharmacol 5, 404– 417. Martin, J. D., King, D. M., Slauch, J. M. & Frisque, R. J. (1985). Differences in regulatory sequences of naturally occurring JC virus variants. J Virol 53, 306–311. Marzocchetti, A., Wuthrich, C., Tan, C. S., Tompkins, T., Bernal- Cano, F., Bhargava, P., Ropper, A. H. & Koralnik, I. J. (2008). Rearrangement of the JC virus regulatory region sequence in the bone marrow of a patient with rheumatoid arthritis and progressive multifocal leukoencephalopathy. J Neurovirol 14, 455–458. Matsuda, M., Jona, M., Yasui, K. & Nagashima, K. (1987). Genetic characterization of JC virus Tokyo-1 strain, a variant oncogenic in rodents. Virus Res 7, 159–168. Messam, C. A., Hou, J. & Major, E. O. (2000). Coexpression of nestin in neural and glial cells in the developing human CNS defined by a human-specific anti-nestin antibody. Exp Neurol 161, 585–596. Messam, C. A., Hou, J., Gronostajski, R. M. & Major, E. O. (2003). Lineage pathway of human brain progenitor cells identified by JC virus susceptibility. Ann Neurol 53, 636–646. Monaco, M. C., Sabath, B. F., Durham, L. C. & Major, E. O. (2001). JC virus multiplication in human hematopoietic progenitor cells requires the NF-1 class D transcription factor. J Virol 75, 9687–9695. Ondek, B., Shepard, A. & Herr, W. (1987). Discrete elements within the SV40 enhancer region display different cell-specific enhancer activities. EMBO J 6, 1017–1025. Petterson, M. & Schaffner, W. (1987). A purine-rich DNA sequence motif present in SV40 and lymphotropic papovavirus binds a lymphoid-specific factor and contributes to enhancer activity in lymphoid cells. Genes Dev 1, 962–972. Pugh, B. F. & Tjian, R. (1991). Transcription from a TATA-less promoter requires a multisubunit TFIID complex. Genes Dev 5, 1935– 1945. Rao, S., Garrett-Sinha, L. A., Yoon, J. & Simon, M. C. (1999a). The Ets factors PU.1 and Spi-B regulate the transcription in vivo of P2Y10, a lymphoid restricted heptahelical receptor. J Biol Chem 274, 34245– 34252. Rao, S., Matsumura, A., Yoon, J. & Simon, M. C. (1999b). SPI-B activates transcription via a unique proline, serine, and threonine domain and exhibits DNA binding affinity differences from PU.1. J Biol Chem 274, 11115–11124. Ravichandran, V. & Major, E. O. (2008). DNA-binding transcription factor NF-1A negatively regulates JC virus multiplication. J Gen Virol 89, 1396–1401. Ray, D., Bosselut, R., Ghysdael, J., Mattei, M. G., Tavitian, A. & Moreau-Gachelin, F. (1992). Characterization of Spi-B, a transcrip- tion factor related to the putative oncoprotein Spi-1/PU.1. Mol Cell Biol 12, 4297–4304. Rekvig, O. (1997). Polyoma induced autoimmunity to DNA; experimental systems and clinical observations in human SLE. Lupus 6, 325–326. Sabath, B. F. & Major, E. O. (2002). Traffic of JC virus from sites of initial infection to the brain: the path to progressive multifocal leukoencephalopathy. J Infect Dis 186, S180–S186. 3051