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HTLV-1: a re-emerging human pathogen

Thematic Series

Edited by Genoveffa Franchini and Cynthia Masison


HTLV-1 is the only known retrovirus to directly cause cancer in humans. HTLV-1 discovered in the late seventy at the NIH in 1980, is transmitted through breast feeding, trans-placentally, sexually and by blood transfusion and organ transplants. HTLV-1 causes a lethal disease, Adult T-cell Leukemia/Lymphoma (ATLL), and a plethora of inflammatory conditions such as uveitis and dermatitis including the neurological degenerative condition designated as Tropical Spastic Paraparesis/HTLV-1 Associated Myelopathy (TSP/HAM) that results in paralysis of the lower limbs. HTLV-1 infection affects millions of people worldwide and currently there is neither targeted antiretroviral therapy nor a vaccine for HTLV-1.

There are several sub-types of HTLV-1. The most prevalent are HTLV-1 subtypes A and B that are found worldwide and are endemic in Japan, the Caribbean, South America and Africa. However, pockets of HTLV-1 infections have also been described in the United States, Iran, Romania and more recently in the UK. In contrast, HTLV-1C, found first in Melanesia in 1993, was described later in New Caledonia and Australia, appears limited to Oceania. It is estimated that HTLV-1C has evolved independently in remote indigenous populations of Oceania in the last 40,000 years.

The current prevalence of HTLV-1 infection in the world is not known, as the last large-scale epidemiological studies were performed more than 30 years ago. Recently, an extraordinarily high prevalence of HTLV-1C, up to 50% in both female and males, has been described in underserved communities in the Norther Territory of Australia. HTLV-1C infection is associated not only with ATLL and TSP/HAM but also with a high mortality at a young age (mid 40s), due to lung inflammation, bronchiectasis, and infectious diseases. By the age of 40, both sexes exhibit a 30-40% HTLV-1C seroprevalence.

Despite the serious health problem caused by infection with all HTLV-1 subtypes, infection by these viruses has become a neglected condition and only palliative treatments are available to the 10-20 million of HTLV-1 infected individuals living mostly in resource deprived countries. Furthermore, the serious medical condition associated with HTLV-1C infection in indigenous populations of Australia, highlights the urgent need to extend HTLV-1 research.

Research on HTLV-1, a virus that has adapted to humans since ancient time, has thought us unexpected novel viral strategies to hijack host cellular pathways in T-cells and to counteract immune responses. There is an urgent need to discover novel preventive or therapeutic remedies for this virus that may relieve not only the suffering of HTLV-1 infected individuals but also augment our understanding of other chronic infection with cancer viruses.

The recent awareness of the serious medical condition associated with HTLV-1C infection in indigenous populations of Australia, highlights the urgent need to revitalize  HTLV-1 research. Thus, the scope of this collection is to summarize what is known on HTLV-1 replication, pathogenesis, treatment and prevention and identify essential areas of unmet need in HTLV-1 basic and translational research.


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  1. Human T-cell leukemia virus type 1 (HTLV-1) infects primarily CD4+ T-lymphocytes and evoques severe diseases, predominantly Adult T-Cell Leukemia/ Lymphoma (ATL/L) and HTLV-1-associated Myelopathy/ Tropical Spast...

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  2. Human T-cell lymphotropic virus type 1 (HTLV-1) is the etiological agent of HTLV associated myelopathy/ Tropical Spastic Paraparesis (HAM/TSP) and Adult T cell leukemia/lymphoma (ATLL), in around 2–5% of the i...

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  3. Adult T-cell leukemia lymphoma (ATLL) is a chemotherapy-resistant malignancy with a median survival of less than one year that will afflict between one hundred thousand and one million individuals worldwide wh...

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  4. Simian T-cell leukemia virus type 1 (STLV-1) is disseminated among various non-human primate species and is closely related to human T-cell leukemia virus type 1 (HTLV-1), the causative agent of adult T-cell l...

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  5. Human T cell leukemia virus type-1 (HTLV-1) was the first retrovirus found to cause cancer in humans, but the mechanisms that drive the development of leukemia and other diseases associated with HTLV-1 infecti...

    Authors: Maria Omsland, Micol Silic-Benussi, Ramona Moles, Sarkis Sarkis, Damian F. J. Purcell, David Yurick, Georges Khoury, Donna M. D’Agostino, Vincenzo Ciminale and Genoveffa Franchini

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  6. Adult T-cell leukemia-lymphoma (ATL) is an aggressive mature lymphoid proliferation associated with poor prognosis. Standard of care includes chemotherapy and/or the combination of zidovudine and interferon-al...

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  7. HTLV-1 was the first described human retrovirus and was soon found to be associated with severe clinical diseases, including a devastating lymphoma/leukemia and other inflammatory diseases. Although HTLV-2 is ...

    Authors: Ricardo Ishak, Marluísa de Oliveira Guimarães Ishak and Antonio Carlos R. Vallinoto

    Citation: Retrovirology 2020 17:4

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  8. Human T cell leukemia virus type 1 (HTLV-1) causes adult T-cell leukemia-lymphoma (ATL) and inflammatory diseases. The HTLV-1 bZIP factor (HBZ) gene is constantly expressed in HTLV-1 infected cells and ATL cel...

    Authors: Masao Matsuoka and Jean-Michel Mesnard

    Citation: Retrovirology 2020 17:2

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  9. Human T-cell leukemia virus type 1 (HTLV-1) is the etiologic agent of adult T-cell leukemia/lymphoma (ATL) and the neurological disorder HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). The...

    Authors: Michael P. Martinez, Xiaogang Cheng, Ancy Joseph, Jacob Al-Saleem, Amanda R. Panfil, Marilly Palettas, Wessel P. Dirksen, Lee Ratner and Patrick L. Green

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  10. The human T cell leukemia virus type 1 (HTVL-1), first reported in 1980 by Robert Gallo’s group, is the etiologic agent of both cancer and inflammatory diseases. Despite approximately 40 years of investigation...

    Authors: Sarkis Sarkis, Veronica Galli, Ramona Moles, David Yurick, Georges Khoury, Damian F. J. Purcell, Genoveffa Franchini and Cynthia A. Pise-Masison

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  11. The extraordinarily high prevalence of HTLV-1 subtype C (HTLV-1C) in some isolated indigenous communities in Oceania and the severity of the health conditions associated with the virus impress the great need f...

    Authors: Ramona Moles, Sarkis Sarkis, Veronica Galli, Maria Omsland, Damian F. J. Purcell, David Yurick, Georges Khoury, Cynthia A. Pise-Masison and Genoveffa Franchini

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  12. Few years after HTLV-1 identification and isolation in humans, STLV-1, its simian counterpart, was discovered. It then became clear that STLV-1 is present almost in all simian species. Subsequent molecular epi...

    Authors: Brice Jégado, Fatah Kashanchi, Hélène Dutartre and Renaud Mahieux

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  13. Human T cell leukaemia virus type 1 (HTLV-1) is a retrovirus associated with human diseases such as adult T-cell leukaemia/lymphoma and HTLV-1 associated myelopathy/tropical spastic paraparesis. In contrast to...

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  14. Immunity against pathogens evolved through complex mechanisms that only for sake of simplicity are defined as innate immunity and adaptive immunity. Indeed innate and adaptive immunity are strongly intertwined...

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  15. Arawete and Asurini Indian tribes were revisited after a 36-year follow-up in search of HTLV infections. 46 persons (23 from each tribe) were tested for HTLV-1/2 antibodies and viral DNA. None were positive; t...

    Authors: Antonio C. R. Vallinoto, Mateus I. Otake, Paulo V. N. R. Sousa, Felipe T. Lopes, Eliene R. P. Sacuena, Maria A. F. Queiroz, Greice L. C. Costa, Marluísa O. G. Ishak, Izaura M. V. Cayres-Vallinoto, João F. Guerreiro and Ricardo Ishak

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  16. Vaccination against retroviruses is a challenge because of their ability to stably integrate into the host genome, undergo long-term latency in a proportion of infected cells and thereby escape immune response...

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  17. Human T-cell leukemia virus type-1 (HTLV-1) causes adult T-cell leukemia/lymphoma (ATL), HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP), and other inflammatory diseases. There is no diseas...

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  18. Human T cell leukemia virus type 1 (HTLV-1) was the first discovered human retrovirus and the etiologic agent of adult T-cell leukemia and HTLV-1-associated myelopathy/tropical spastic paraparesis. Shortly aft...

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