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Molecular Pathology of HTLV-1

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Front. Microbiol. | doi: 10.3389/fmicb.2018.00278

How to control HTLV-1-associated diseases: preventing de novo cellular infection using antiviral therapy

 amandine pasquier1, sandrine alais1,  loic roux2, Maria-Isabel Thoulouze3, karine alvarez2,  Chloé Journo1, helene dutartre1 and  Renaud Mahieux1*
  • 1biology, École normale supérieure de Lyon, France
  • 2architecture et fonction des macromolécules biologiques, Aix-Marseille Université, France
  • 3Institut Pasteur, France

Five to ten million individuals are infected by Human T-cell Leukemia Virus type 1 (HTLV-1). HTLV-1 is transmitted through prolonged breast-feeding, by sexual contacts and by transmission of infected T lymphocytes through blood transfusion. One to ten percent of infected carriers will develop a severe HTLV-1-associated disease: Adult-T-cell leukemia/lymphoma (ATLL), or a neurological disorder named Tropical Spastic Paraparesis/HTLV-1 Associated Myelopathy (TSP/HAM). In vivo, HTLV-1 is mostly detected in CD4+ T-cells, and to a lesser extent in CD8+ T cells and dendritic cells. There is a strong correlation between HTLV-1 proviral load (PVL) and clinical status of infected individuals. Thus, reducing PVL could be part of a strategy to prevent or treat HTLV-1-associated diseases among carriers. Treatment of ATLL patients using conventional chemotherapy has very limited benefit. Some chronic and acute ATLL patients are however efficiently treated with a combination of interferon α and zidovudine (IFN-α/AZT), to which arsenic trioxide is added in some cases. On the other hand, no efficient treatment for TSP/HAM patients has been described yet. It is therefore crucial to develop therapies that could either prevent the occurrence of HTLV-1-associated diseases or at least block the evolution of the disease in the early stages. In vivo, reverse transcriptase (RT) activity is low in infected cells, which is correlated with a clonal mode of viral replication. This renders infected cells resistant to nucleoside reverse transcriptase inhibitors such as AZT. However, histone deacetylase inhibitors (HDACi) associated to AZT efficiently induces viral expression and prevent de novo cellular infection. In asymptomatic STLV-1 infected non-human primates, HDACi/AZT combination allows a strong decrease in the PVL. Unfortunately, rebound in the PVL occurs when the treatment is stopped, highlighting the need for better antiviral compounds. Here, we review previously used strategies targeting HTLV-1 replication. We also tested a series of HIV-1 RT inhibitors in an in vitro anti-HTLV-1 screen, and report that bis-POM-PMEA (adefovir dipivoxil) and bis-POC-PMPA (tenofovir disoproxil) are much more efficient compared to AZT to decrease HTLV-1 cell-to-cell transmission in vitro. Our results suggest that revisiting already established antiviral drugs is an interesting approach to discover new anti-HTLV-1 drugs.

Keywords: HTLV-I Infections, Antiviral therapy, Prodrugs, Proviral load, cell-cell transmission

Received: 20 Dec 2017; Accepted: 07 Feb 2018.

Edited by:

Umberto Bertazzoni, University of Verona, Italy

Reviewed by:

Johan Van Weyenbergh, KU Leuven, Belgium
Beatrice Macchi, Dipartimento MEDICINA dei SISTEMI, Università degli Studi di Roma Tor Vergata, Italy  

Copyright: © 2018 pasquier, alais, roux, Thoulouze, alvarez, Journo, dutartre and Mahieux. 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) and the copyright owner 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: Prof. Renaud Mahieux, École normale supérieure de Lyon, biology, Lyon, France,