Human T-lymphotropic virus 2

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Human T-lymphotropic virus 2
SpecialtyInfectious diseases
SymptomsMild cognitive Impairment, Mycosis fungoides
DurationChronic, incurable
CausesHTLV-2
Risk factorsUnsafe sex, haemophiliacs
Diagnostic methodBlood test
Differential diagnosisHIV/AIDS, Lymphoma, HTLV-1
PreventionPracticing safe-sex, use of clean needles, screening blood transfusions, Avoiding breastfeeding.
MedicationAntiretrovirals, chemotherapy
Prognosis95% present with no symptoms, generally good
Frequency15-20 million people worldwide
Primate T-lymphotropic virus 2
Virus classification Edit this classification
(unranked): Virus
Realm: Riboviria
Kingdom: Pararnavirae
Phylum: Artverviricota
Class: Revtraviricetes
Order: Ortervirales
Family: Retroviridae
Genus: Deltaretrovirus
Species:
Primate T-lymphotropic virus 2

A

HTLV-I, human T-lymphotropic virus 2 (HTLV-II) shares approximately 70% genomic homology (structural similarity) with HTLV-I. It was discovered by Robert Gallo and colleagues.[1][2]

HTLV-2 is prevalent among the indigenous populations in Africa and the Indian-American tribes in Central and South America as well as among drug users in Europe and North America[3] It can be passed down from mother to child through breastmilk and genetically as well from either parent.

HTLV-II entry in target cells is mediated by the glucose transporter GLUT1.[4]

A phylogeny of the subtypes of HTLV and their relationships between endogenous and exogenous retroviruses in the human genome. HERV = human endogenous retrovirus, SFV = simian foamy virus

Virology

Cutaneous T-cell lymphoma (CTCL).[5] In one study involving cultured lymphocytes from patients with mycosis fungoides (Figure 1), PCR amplification showed gene sequences of HTLV-II. This finding may suggest a possible correlation with HTLV-2 and CTCL. Further research and studies must be conducted to show a positive relationship.[1]

Transmission

Perinatal transmission and breastfeeding and through blood transfusion, sexual contact, and use of intravenous drugs.[3]

Epidemiology

HTLV-1 and HTLV-2 are both involved in actively spreading epidemics, affecting 15-20 million people worldwide. [4] In the United States, the overall prevalence is 22 per 100,000 population, with HTLV-2 more common than HTLV-1. Data collection performed from 2000 to 2009 among US blood donors has shown a general decline since the 1990s.[6]

Symptoms

Human T- leukemia, type 2 (HTLV-2) generally causes no signs or

symptoms. Although HTLV-2 has not been definitively linked with any specific health problems, scientists suspect that some affected people may later develop neurological problems such as:[7][6]
Figure 1. Mycosis fungoides, a skin disease showing nodules and plaques composed of lymphocytes spread across the skin, has been associated with HTLV-II infection[5]

Although evidence is limited, there may also be a link between HTLV-2 and chronic lung infections (i.e. pneumonia and bronchitis), asthma and dermatitis.[8]

Clinical significance

HTLV-II has not been clearly linked to any disease, but has been associated with several cases of

HAM/TSP)- like neurological disease and may cause chronic lung problems.[citation needed
]

An impact on platelet count has been observed.[9]

In the 1980s, HTLV-2 was identified in a patient with an unidentified T cell

lymphoproliferative disease that was described as having characteristics similar to the B cell disorder, hairy cell leukemia.[10] HTLV-2 was identified in a second patient with a T cell lymphoproliferative disease; this patient later developed hairy cell leukemia, but HTLV-2 was not found in the hairy cell clones.[11] The cause of hairy cell leukemia is not known, but it is no longer believed to be related to viral infections.[citation needed
]

Treatment

There are few

antiretrovirals that can slow the viral load but no cure or definitive treatment exists for HTLV-2.[8]

Diagnosis

Human T- leukemia, type 2 (HTLV-2) is usually diagnosed based on blood tests that detect to the virus. However, HTLV-2 is often never suspected or diagnosed since most people never develop any signs or symptoms of the infection. Diagnosis may occur during  for blood donation, testing performed due to an infection, or a work-up for an HTLV-2-associated medical problems.[8]

Prevention

Due to there being no cure for HTLV II the prevention is focused on early detection and preventing the spread of HTLV-2 to others.  blood donors, promoting safe sex and discouraging needle sharing can decrease the number of new infections. Mother-to-child transmission can be reduced by screening pregnant women so infected mothers can avoid breastfeeding.[8]

Prognosis

The long-term outlook for most people infected with HTLV-2 is good. Infection with HTLV-2 is lifelong, but 95% of affected people have no signs or symptoms of the condition. Although, HTLV-2-related health problems tend to be significantly milder than those associated with HTLV1.[8]

References

  1. ^
    PMID 20692726
    .
  2. ^ "Robert gallo discovers htlv2 and 1". Retrieved 23 February 2019.
  3. ^
    PMID 25120538
    .
  4. PMID 14622599
    .
  5. ^ a b "Journal of the American Academy of Dermatology". www.jaad.org. Retrieved 2019-02-22.
  6. ^ a b "Human T-Cell Lymphotropic Viruses (HTLV)". Medscape. Retrieved 22 February 2019.
  7. ^ "HTLV Type I and Type II". NORD (National Organization for Rare Disorders). Retrieved 2019-02-22.
  8. ^ a b c d e "Human T-cell leukemia virus type 2". US Department of Health and Human Services | Genetic and Rare Diseases Information Center (GARD) – an NCATS Program. Retrieved 2019-02-22. Public Domain This article incorporates text from this source, which is in the public domain.
  9. PMID 18755983
    .
  10. PMID 6981847
    .
  11. PMID 2827811
    . Retrieved 10 July 2020.
  12. PMID 17376384
    .

External links
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