Front. Microbiol., 09 September 2013 | doi: 10.3389/fmicb.2013.00271

Highlights on distinctive structural and functional properties of HTLV Tax proteins

  • 1Department of Life and Reproduction Sciences, University of Verona, Verona, Italy
  • 2GEMIB laboratory, Center for Medical Research and Molecular Diagnostics, Parma, Italy
  • 3Department of Surgery, Oncology and Gastroenterology, University of Padua, Padua, Italy
  • 4Institute for Microbiological Research J-M Wiame, Laboratory of Microbiology, Université Libre de Bruxelles, Brussels, Belgium

Human T cell leukemia viruses (HTLVs) are complex human retroviruses of the Deltaretrovirus genus. Four types have been identified thus far, with HTLV-1 and HTLV-2 much more prevalent than HTLV-3 or HTLV-4. HTLV-1 and HTLV-2 possess strictly related genomic structures, but differ significantly in pathogenicity, as HTLV-1 is the causative agent of adult T cell leukemia and of HTLV-associated myelopathy/tropical spastic paraparesis, whereas HTLV-2 is not associated with neoplasia. HTLVs code for a protein named Tax that is responsible for enhancing viral expression and drives cell transformation. Much effort has been invested to dissect the impact of Tax on signal transduction pathways and to identify functional differences between the HTLV Tax proteins that may explain the distinct oncogenic potential of HTLV-1 and HTLV-2. This review summarizes our current knowledge of Tax-1 and Tax-2 with emphasis on their structure, role in activation of the NF-κB (nuclear factor kappa-B) pathway, and interactions with host factors.

Keywords: HTLV, Tax proteins, signal transduction, NF-κB

Citation: Romanelli MG, Diani E, Bergamo E, Casoli C, Ciminale V, Bex F and Bertazzoni U (2013) Highlights on distinctive structural and functional properties of HTLV Tax proteins. Front. Microbiol. 4:271. doi: 10.3389/fmicb.2013.00271

Received: 10 July 2013; Paper pending published: 30 July 2013;
Accepted: 20 August 2013; Published online: 09 September 2013.

Edited by:

Akio Adachi, The University of Tokushima Graduate School, Japan

Reviewed by:

Jun-ichi Fujisawa, Kansai Medical University, Japan
Makoto Yamagishi, The University of Tokyo, Japan
Yorifumi Satou, Kumamoto University, Japan

Copyright © 2013 Romanelli, Diani, Bergamo, Casoli, Ciminale, Bex and Bertazzoni. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

*Correspondence: Maria G. Romanelli, Department of Life and Reproduction Sciences, University of Verona, Strada le Grazie 8, 37134 Verona, Italy e-mail:

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