Primate T-lymphotropic virus#Tax

{{missing information|section|more on the fresh new genes, like Tax and Rex|date=January 2023}}

File:Pavesi ploscompbio 2013 fig4.png

HTLV-1 is the prototypical PTLV, from which comparisons are drawn for the newly-known types. A retrovirus, PTLV shares the common gag-pro-pol-env set of genes, yet shows great complexity in the unique 3' end. These new proteins provide a great source of new adaptive function:{{cite journal |last1=Pavesi |first1=Angelo |last2=Magiorkinis |first2=Gkikas |last3=Karlin |first3=David G. |title=Viral Proteins Originated De Novo by Overprinting Can Be Identified by Codon Usage: Application to the "Gene Nursery" of Deltaretroviruses |journal=PLOS Computational Biology |date=15 August 2013 |volume=9 |issue=8 |pages=e1003162 |doi=10.1371/journal.pcbi.1003162|pmid=23966842 |pmc=3744397 |doi-access=free |bibcode=2013PLSCB...9E3162P }}

• {{anchor|Tax}}Tax, the transactivator, is common to all Deltaretrovirus. In a HTLV-1 infection, it is the first protein to be expressed, and in turn is responsible for the expression of the provirus at the LTR during the early phase.{{cite journal |last1=Nakano |first1=K |last2=Watanabe |first2=T |title=HTLV-1 Rex: the courier of viral messages making use of the host vehicle. |journal=Frontiers in Microbiology |date=2012 |volume=3 |pages=330 |doi=10.3389/fmicb.2012.00330 |pmid=22973269|pmc=3434621 |doi-access=free }}
• Rex is also common to all extant Deltaretrovirus. As it gets expressed, Rex binds mRNA to control the extent of splicing.
• HBZ is the first novel protein, only common among PLTV. It encodes a basic leucine zipper, and is known to be enhance HLTV-1 replication and oncogenicity. It is encoded in the opposite ("antisense") direction compared to all other ORFs.
• p12, p8, p30, p13 are the newest class of proteins only found in HTLV-1.{{cite journal |last1=Bai |first1=XT |last2=Nicot |first2=C |title=Overview on HTLV-1 p12, p8, p30, p13: accomplices in persistent infection and viral pathogenesis. |journal=Frontiers in Microbiology |date=2012 |volume=3 |pages=400 |doi=10.3389/fmicb.2012.00400 |pmid=23248621|pmc=3518833 |doi-access=free }}

HTLV-1 has three tandem imperfect 21-base repeats as the long terminal repeat, but other PTLVs only have two.

The lifecycle is common to retroviruses, starting at the envelope glycoprotein (Env) surface subunit (SU) binding to a cellular receptor (in this case GLUT1 and a host of other molecules),{{cite journal |last1=Ghez |first1=D |last2=Lepelletier |first2=Y |last3=Jones |first3=KS |last4=Pique |first4=C |last5=Hermine |first5=O |title=Current concepts regarding the HTLV-1 receptor complex. |journal=Retrovirology |date=29 November 2010 |volume=7 |pages=99 |doi=10.1186/1742-4690-7-99 |pmid=21114861|pmc=3001707 |doi-access=free }} and ending with lysis of the cell (in this case, a lymphocyte).{{cite web |title=Primate T-lymphotropic virus 1 ~ ViralZone |url=https://viralzone.expasy.org/59 |website=viralzone.expasy.org}} The virion is spherical to pleomorphic, about 80-100 nm in diameter. Unusually, the single-stranded RNA genome is present in two copies, forming a dimer specifically packed by parts of the gag protein.{{cite journal |last1=Wu |first1=W |last2=Hatterschide |first2=J |last3=Syu |first3=YC |last4=Cantara |first4=WA |last5=Blower |first5=RJ |last6=Hanson |first6=HM |last7=Mansky |first7=LM |last8=Musier-Forsyth |first8=K |title=Human T-cell leukemia virus type 1 Gag domains have distinct RNA-binding specificities with implications for RNA packaging and dimerization. |journal=The Journal of Biological Chemistry |date=19 October 2018 |volume=293 |issue=42 |pages=16261–16276 |doi=10.1074/jbc.RA118.005531 |pmid=30217825|pmc=6200928 |doi-access=free }}

The use of "HTLV-3" can cause some confusion, because the name HTLV-III was one of the names for HIV in early AIDS literature, but has since fallen out of use.{{MeshName|Human+T-Lymphotropic+Virus+Type+III}} The name HTLV-IV has also been used to describe HIV-2.{{MeshName|Human+T+Lymphotropic+Virus+Type+IV}} A large Canadian study documented this confusion among healthcare workers, where >90% of HTLV tests ordered by physicians were actually intended to be HIV tests.{{cite journal|last=Siemieniuk|first=Reed|author2=Fonseca, Kevin|author3=Gill M. John|date=November 2012|title=Using Root Cause Analysis and Form Redesign to Reduce Incorrect Ordering of HIV Tests|journal=The Joint Commission Journal on Quality and Patient Safety|series=11|volume=38|issue=11|pages=506–512|doi=10.1016/S1553-7250(12)38067-7|pmid=23173397}}

{{main|HTLV-1}}

PTLV-1 is the medically most important species in the class. Discovered by Robert Gallo and colleagues in 1980,{{cite journal |vauthors=Poiesz BJ, Ruscetti FW, Gazdar AF, Bunn PA, Minna JD, Gallo RC |title=Detection and isolation of type C retrovirus particles from fresh and cultured lymphocytes of a patient with cutaneous T-cell lymphoma |journal=Proc. Natl. Acad. Sci. U.S.A. |volume=77 |issue=12 |pages=7415–9 |year=1980 |pmid=6261256 |pmc=350514 |doi=10.1073/pnas.77.12.7415|bibcode=1980PNAS...77.7415P |doi-access=free }} HTLV-1 has been implicated in several kinds of diseases, including tropical spastic paraparesis and as a virus cancer link for adult T-cell leukemia/lymphoma. Between 1 in 20 and 1 in 25 infected people are thought to develop cancer as a result of the virus.{{cite journal|last=WELSH|first=JAMES S.|title=Contagious Cancer|journal=The Oncologist|date=January 2011|volume=16|issue=1|pages=1–4|doi=10.1634/theoncologist.2010-0301|pmid=21212437|pmc=3228048}} STLV-1 is oncogenic in Japanese macaques.{{cite journal |last1=Miura |first1=Michi |last2=Tanabe |first2=Junko |last3=Sugata |first3=Kenji |last4=Zhao |first4=Tiejun |last5=Ma |first5=Guangyong |last6=Miyazato |first6=Paola |last7=Yasunaga |first7=Jun-Ichiro |last8=Matsuoka |first8=Masao |year=2014 |title=STLV-1-infected Japanese macaque as a model of HTLV-1 infection |journal=Retrovirology |volume=11 |issue=Suppl 1 |pages=O12 |doi=10.1186/1742-4690-11-S1-O12|pmc=4042625 |doi-access=free }}

HTLV-1 has seven reported subtypes (subtypes A through G).{{Cite journal|last1=Verdonck|first1=Kristien|last2=González|first2=Elsa|last3=Van Dooren|first3=Sonia|last4=Vandamme|first4=Anne-Mieke|last5=Vanham|first5=Guido|last6=Gotuzzo|first6=Eduardo|date=April 2007|title=Human T-lymphotropic virus 1: recent knowledge about an ancient infection|url=https://linkinghub.elsevier.com/retrieve/pii/S1473309907700816|journal=The Lancet Infectious Diseases|language=en|volume=7|issue=4|pages=266–281|doi=10.1016/S1473-3099(07)70081-6|pmid=17376384|url-access=subscription}} The great majority of infections are caused by the cosmopolitan subtype A.{{cite journal |vauthors=Gonçalves DU, Proietti FA, Ribas JG, Araújo MG, Pinheiro SR, Guedes AC, Carneiro-Proietti AB |title=Epidemiology, treatment, and prevention of human T-cell leukemia virus type 1-associated diseases |journal=Clin. Microbiol. Rev. |volume=23 |issue=3 |pages=577–89 |year=2010 |pmid=20610824 |pmc=2901658 |doi=10.1128/CMR.00063-09 }} The HTLV-I/STLV-I history might suggest a simian migration from Asia to Africa not much earlier than 19,500–60,000 years ago.{{cite journal |vauthors=Salemi M, Desmyter J, Vandamme AM |title=Tempo and mode of human and simian T-lymphotropic virus (HTLV/STLV) evolution revealed by analyses of full-genome sequences |journal=Molecular Biology and Evolution |volume=17 |issue=3 |pages=374–86 |date=March 2000 |pmid=10723738 |doi=10.1093/oxfordjournals.molbev.a026317|doi-access=free }}

{{Main|Human T-lymphotropic virus 2}}

Discovered in 1982,{{cite journal |vauthors=Kalyanaraman VS, Sarngadharan MG, Robert-Guroff M, Miyoshi I, Golde D, Gallo RC |title=A new subtype of human T-cell leukemia virus (HTLV-II) associated with a T-cell variant of hairy cell leukemia |journal=Science |volume=218 |issue=4572 |pages=571–3 |date=November 1982 |pmid=6981847 |doi= 10.1126/science.6981847|bibcode=1982Sci...218..571K }} HTLV-2 has not yet been conclusively linked to any disease.{{cite web|url=https://rarediseases.org/rare-diseases/htlv-type-i-and-type-ii/|title=HTLV Type I and Type II|website=NORD (National Organization for Rare Disorders)|language=en-US|access-date=2019-02-22}} It generally causes no symptoms. It might impact the platelet count,{{cite journal |vauthors=Bartman MT, Kaidarova Z, Hirschkorn D, etal |title=Long-term increases in lymphocytes and platelets in human T-lymphotropic virus type II infection |journal=Blood |volume=112 |issue=10 |pages=3995–4002 |date=November 2008 |pmid=18755983 |pmc=2581993 |doi=10.1182/blood-2008-05-155960 }} contribute to chronic lung infections,{{cite web|url=https://rarediseases.info.nih.gov/diseases/9783/human-t-cell-leukemia-virus-type-2|title=Human T-cell leukemia virus type 2|publisher=US Department of Health and Human Services {{!}} Genetic and Rare Diseases Information Center (GARD) – an NCATS Program|access-date=2019-02-22|archive-date=2021-03-18|archive-url=https://web.archive.org/web/20210318071636/https://rarediseases.info.nih.gov/diseases/9783/human-t-cell-leukemia-virus-type-2|url-status=dead}} {{PD-notice}} or lead to future cutaneous T-cell lymphoma (CTCL),{{Cite journal|last1=Mirvish|first1=Ezra D.|last2=Pomerantz|first2=Rebecca G.|last3=Geskin|first3=Larisa J.|title=Infectious agents in cutaneous T-cell lymphoma|journal=Journal of the American Academy of Dermatology|volume=64|issue=2|pages=423–431|doi=10.1016/j.jaad.2009.11.692|pmid=20692726|year=2011|pmc=3954537}} among a host of other proposals.

HTLV-3 was discovered in 2005 in rural Cameroon, and were, it is presumed, transmitted from monkeys to hunters of monkeys through bites and scratches.{{cite journal |last1=Mahieux |first1=R. |last2=Gessain |first2=Antoine |title=The human HTLV-3 and HTLV-4 retroviruses: New members of the HTLV family |journal=Pathologie Biologie |volume=57 |issue=2 |pages=161–6 |year=2009 |pmid=18456423 |doi=10.1016/j.patbio.2008.02.015}}{{cite journal |last1=Mahieux |first1=R |last2=Gessain |first2=A |title=Les nouveaux rétrovirus humains HTLV-3 et HTLV-4 |trans-title=New human retroviruses: HTLV-3 and HTLV-4 |language=fr |journal=Médecine Tropicale |volume=65 |issue=6 |pages=525–8 |year=2005 |pmid=16555510 |url=http://www.revuemedecinetropicale.com/525-528_-_av_-_mahieux.pdf |access-date=2010-12-10 |archive-url=https://web.archive.org/web/20110715180113/http://www.revuemedecinetropicale.com/525-528_-_av_-_mahieux.pdf |archive-date=2011-07-15 |url-status=live }} Multiple strains have been identified.{{cite journal |last1=Calattini |first1=Sara |last2=Betsem |first2=Edouard |last3=Bassot |first3=Sylviane |last4=Chevalier |first4=SéBastien Alain |last5=Mahieux |first5=Renaud |last6=Froment |first6=Alain |last7=Gessain |first7=Antoine |title=New Strain of Human T Lymphotropic Virus (HTLV) Type 3 in a Pygmy from Cameroon with Peculiar HTLV Serologic Results |journal=The Journal of Infectious Diseases |volume=199 |issue=4 |pages=561–4 |year=2009 |pmid=19099485 |doi=10.1086/596206 |url=https://hal.archives-ouvertes.fr/hal-00358082/file/Calattini2009.pdf |access-date=2019-09-01 |archive-url=https://web.archive.org/web/20190901110324/https://hal.archives-ouvertes.fr/hal-00358082/file/Calattini2009.pdf |archive-date=2019-09-01 |url-status=live |doi-access=free }} A strain has been fully sequenced.{{cite journal |last1=Calattini |first1=S. |last2=Chevalier |first2=S. A. |last3=Duprez |first3=R. |last4=Afonso |first4=P. |last5=Froment |first5=A. |last6=Gessain |first6=A. |last7=Mahieux |first7=R. |title=Human T-Cell Lymphotropic Virus Type 3: Complete Nucleotide Sequence and Characterization of the Human Tax3 Protein |journal=Journal of Virology |volume=80 |issue=19 |pages=9876–88 |year=2006 |pmid=16973592 |pmc=1617244 |doi=10.1128/JVI.00799-06}}{{cite journal |last1=Chevalier |first1=S. A. |last2=Ko |first2=N. L. |last3=Calattini |first3=S. |last4=Mallet |first4=A. |last5=Prevost |first5=M.-C. |last6=Kehn |first6=K. |last7=Brady |first7=J. N. |last8=Kashanchi |first8=F. |last9=Gessain |first9=A. |last10=Mahieux |first10=R. |title=Construction and Characterization of a Human T-Cell Lymphotropic Virus Type 3 Infectious Molecular Clone |journal=Journal of Virology |volume=82 |issue=13 |pages=6747–52 |year=2008 |pmid=18417569 |pmc=2447071 |doi=10.1128/JVI.00247-08|display-authors=8 }}

PTLV-3 is about 40% different from PTLV-1 and -2. It occasionally cross-reacts with HTLV-2 tests. It is not yet known how much further transmission has occurred among humans, or whether the virus can cause disease.{{cite journal |last1=Mahieux |first1=R |last2=Gessain |first2=A |title=HTLV-3/STLV-3 and HTLV-4 viruses: discovery, epidemiology, serology and molecular aspects. |journal=Viruses |date=July 2011 |volume=3 |issue=7 |pages=1074–90 |doi=10.3390/v3071074 |pmid=21994771|pmc=3185789 |doi-access=free }}

HTLV-4 was discovered at the same site as HTLV-3 in 2005. Even less is known about this virus, as no simian counterpart has ever been found. The International Committee on Taxonomy of Viruses does not recognize it as a species. The sequence is, however, available.

STLV-5 is a name used for a highly divergent PTLV-1 strain isolated from Macaca arctoides.

HTLV-1 and HTLV-2 can be transmitted sexually,{{cite journal |last1=Rodriguez |first1=Evelyn M. |last2=de Moya |first2=E. Antonio |last3=Guerrero |first3=Ernesto |last4=Monterroso |first4=Edgar R. |last5=Quinn |first5=Thomas C. |last6=Puello |first6=Elizardo |last7=de Quiñones |first7=Margarita Rosado |last8=Thorington |first8=Bruce |last9=Glasner |first9=Peter D. |last10=Zacarias |first10=F |title=HIV-1 and HTLV-I in sexually transmitted disease clinics in the Dominican Republic |journal=Journal of Acquired Immune Deficiency Syndromes |volume=6 |issue=3 |pages=313–8 |year=1993 |pmid=8450407 |url=http://journals.lww.com/jaids/Abstract/1993/03000/HIV_1_and_HTLV_I_in_Sexually_Transmitted_Disease.18.aspx |display-authors=8 |access-date=2010-12-10 |archive-url=https://web.archive.org/web/20121006124047/http://journals.lww.com/jaids/Abstract/1993/03000/HIV_1_and_HTLV_I_in_Sexually_Transmitted_Disease.18.aspx |archive-date=2012-10-06 |url-status=live }}{{cite journal |last1=Roucoux |first1=Diana F. |last2=Wang |first2=Baoguang |last3=Smith |first3=Donna |last4=Nass |first4=Catharie C. |last5=Smith |first5=James |last6=Hutching |first6=Sheila T. |last7=Newman |first7=Bruce |last8=Lee |first8=Tzong-Hae |last9=Chafets |first9=Daniel M. |last10=Murphy |first10=Edward L. |last11=Htlv Outcomes Study |first11=Investigators |title=A Prospective Study of Sexual Transmission of Human T Lymphotropic Virus (HTLV)-I and HTLV-II |journal=The Journal of Infectious Diseases |volume=191 |issue=9 |pages=1490–7 |year=2005 |pmid=15809908 |doi=10.1086/429410|display-authors=8 |doi-access= }} by blood to blood contact (e.g. by blood transfusion or sharing needles when using drugs){{Cite web |url=http://www.htlv1.eu/htlv_one.html#how |title=Die Vorteile eines GPS-Tracking-Halsbandes für Hunde - HTLV1 Hunde GPS Tracker Vergleich |access-date=2015-11-04 |archive-url=https://web.archive.org/web/20151102044516/http://www.htlv1.eu/htlv_one.html#how |archive-date=2015-11-02 |url-status=live }}{{Cite web |url=http://www.htlv1.eu/htlv_two.html#how |title=Grundlagen der Druckluft Drehdurchführungen – htlv1.eu |access-date=2015-11-04 |archive-url=https://web.archive.org/web/20151120020717/http://www.htlv1.eu/htlv_two.html#how |archive-date=2015-11-20 |url-status=live }} and via breast feeding.{{cite journal |vauthors=Coovadia HM, Rollins NC, Bland RM, Little K, Coutsoudis A, Bennish ML, Newell ML |title=Mother-to-child transmission of HIV-1 infection during exclusive breastfeeding in the first 6 months of life: an intervention cohort study |journal=Lancet |volume=369 |issue=9567 |pages=1107–16 |year=2007 |pmid=17398310 |doi=10.1016/S0140-6736(07)60283-9 |s2cid=6183061 }}

Two HTLVs are well established. HTLV-1 and HTLV-2 are both involved in actively spreading epidemics, affecting 15–20 million people worldwide.{{Cite journal|last1=de Thé|first1=G.|last2=Kazanji|first2=M.|date=1996|title=An HTLV-I/II vaccine: from animal models to clinical trials?|journal=Journal of Acquired Immune Deficiency Syndromes and Human Retrovirology |volume=13|issue=Suppl 1 |pages=S191–198|issn=1077-9450|pmid=8797723|doi=10.1097/00042560-199600001-00029|doi-access=free}}

HTLV-1 is the more clinically significant of the two: at least 500,000 of the individuals infected with HTLV-1 eventually develop an often rapidly fatal leukemia, while others will develop a debilitative myelopathy, and yet others will experience uveitis, infectious dermatitis, or another inflammatory disorder. HTLV-2 is associated with milder neurologic disorders and chronic pulmonary infections. In the United States, HTLV-1/2 seroprevalence rates among volunteer blood donors average 0.016 percent.{{Citation needed|date=December 2017}}

No specific illnesses have yet been associated with HTLV-3 and HTLV-4.

While there is no present licensed vaccine, there are many factors which make a vaccine against HTLV-1 feasible. The virus displays relatively low antigenic variability, natural immunity does occur in humans, and experimental vaccination using envelope antigens has been shown to be successful in animal models. Plasmid DNA vaccines elicit potent and protective immune responses in numerous small-animal models of infectious diseases. However, their immunogenicity in primates appears less potent. In the past two decades a large initiative has been put forth to understand the biological and pathogenic properties of the human T-cell lymphotropic virus type 1 (HTLV-1); this has ultimately led to the development of various experimental vaccination and therapeutic strategies to combat HTLV-1 infection. These strategies include the development of envelope glycoprotein derived B-cell epitopes for the induction of neutralizing antibodies, as well as a strategy to generate a multivalent cytotoxic T-lymphocyte (CTL) response against the HTLV-1 Tax antigen. A vaccine candidate that can elicit or boost anti-gp46 neutralizing antibody response may have a potential for prevention and therapy against HTLV-1 infection.{{cite journal |vauthors=Tanaka Y, Takahashi Y, Kodama A, Tanaka R, Saito M |title=Neutralizing antibodies against human T cell leukemia virus type-I (HTLV-1) eradicate HTLV-1 in combination with autologous peripheral blood mononuclear cells via antibody-dependent cellular cytotoxicity while preventing new infection |journal=Retrovirology |volume=11 |issue=Suppl 1 |pages=O39 |year=2014 |doi=10.1186/1742-4690-11-s1-o39| pmc=4044937 |s2cid=7065527 |url=http://www.retrovirology.com/content/pdf/1742-4690-11-S1-O39.pdf |access-date=2014-03-05 |archive-url=https://web.archive.org/web/20150910111530/http://www.retrovirology.com/content/pdf/1742-4690-11-S1-O39.pdf |archive-date=2015-09-10 |url-status=live |doi-access=free }}

Potential treatments include prosultiamine, a vitamin B-1 derivative, which has been shown to reduce viral load and symptoms;{{Cite web |url=https://www.sciencedaily.com/releases/2013/08/130815084757.htm |title=Nervous System Disease: A New Outlet for an Old Drug? |access-date=2018-03-09 |archive-url=https://web.archive.org/web/20180118010753/https://www.sciencedaily.com/releases/2013/08/130815084757.htm |archive-date=2018-01-18 |url-status=live }} azacytidine, an anti-metabolite, which has been credited with the cure of a patient in Greece;{{cite journal |vauthors=Diamantopoulos PT, Michael M, Benopoulou O, Bazanis E, Tzeletas G, Meletis J, Vayopoulos G, Viniou NA |title=Antiretroviral activity of 5-azacytidine during treatment of a HTLV-1 positive myelodysplastic syndrome with autoimmune manifestations |journal=Virol. J. |volume=9 |pages=1 |year=2012 |pmid=22214262 |pmc=3305386 |doi=10.1186/1743-422X-9-1 |doi-access=free }} tenofovir disoproxil (TDF), a reverse-transcriptase inhibitor used for HIV; cepharanthine, an alkaloid from Stephania cephalantha Hayata;{{cite journal|pmid=22753721|year=2012|last1=Toyama|first1=M|title=Synergistic inhibition of HTLV-1-infected cell proliferation by combination of cepharanthine and a tetramethylnaphthalene derivative|journal=Anticancer Research|volume=32|issue=7|pages=2639–45|last2=Hamasaki|first2=T|last3=Uto|first3=T|last4=Aoyama|first4=H|last5=Okamoto|first5=M|last6=Hashmoto|first6=Y|last7=Baba|first7=M}} and phosphonated carbocyclic 2'-oxa-3'aza nucleosides (PCOANs).{{Cite journal

| last1 = MacChi | first1 = B.

| last2 = Balestrieri | first2 = E.

| last3 = Ascolani | first3 = A.

| last4 = Hilburn | first4 = S.

| last5 = Martin | first5 = F.

| last6 = Mastino | first6 = A.

| last7 = Taylor | first7 = G. P.

| doi = 10.3390/v3050469

| title = Susceptibility of Primary HTLV-1 Isolates from Patients with HTLV-1-Associated Myelopathy to Reverse Transcriptase Inhibitors

| journal = Viruses

| volume = 3

| issue = 12

| pages = 469–483

| year = 2011

| pmid = 21994743

| pmc =3185762

| doi-access = free

}} A newer formulation of TDF, called tenofovir alafenamide (TAF), also has promise as a treatment with less toxicity.{{citation needed|date=November 2022}}{{clear}}

{{Reflist|2}}

• {{eMedicine|med|1038|human T-cell lymphotrophic virus}}
• [http://htlv.net International Retrovirology Association]
• {{MeshName|Human+T-lymphotropic+virus+1}}
• {{MeshName|Human+T-lymphotropic+virus+2}}
• {{cite web |title=Human T-lymphotropic virus 1 |work=NCBI Taxonomy Browser |url=https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&id=11908 |id=11908}}
• {{cite web |title=Human T-lymphotropic virus 2 |work=NCBI Taxonomy Browser |url=https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&id=11909 |id=11909}}
• {{cite web |title=Human T-lymphotropic virus 3 |work=NCBI Taxonomy Browser |url=https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&id=28332 |id=28332}}
• {{cite web |title=Human T-lymphotropic virus 4 |work=NCBI Taxonomy Browser |url=https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&id=318279 |id=318279}}
• {{cite web |title=Untyped Human T-lymphotropic virus |work=NCBI Taxonomy Browser |url=https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&id=318275 |id=318275}}

{{Retroviruses}}

{{Taxonbar|from=Q12258832|from2=Q1280388|from3=Q2720986}}

{{Authority control}}

{{DEFAULTSORT:Human T-Lymphotropic Virus}}

Category:Deltaretroviruses

Category:Unaccepted virus taxa