HUMAN T-LYMPHOTROPIC VIRUS | HTLV1 | ADULT T-CELL LEUKEMIA / LYMPHOMA | Adwoa Biotech

Summary

Human T-Cell Lymphotropic Virus (HTLV-1) is a little-known retrovirus affecting millions globally, with higher prevalence in regions like Japan and Central Australia. Discovered in 1965, it was the first retrovirus shown to cause cancer in humans, leading to Adult T-cell Leukemia/Lymphoma (ATL), a fatal disease. HTLV-1 also causes neurological disorders like Tropical Spastic Paraparesis (TSP). The virus spreads through breastfeeding, sexual contact, and un-screened blood products. Although overshadowed by HIV, HTLV-1's serious health implications emphasize the need for awareness, particularly in endemic areas.

Takeaways

• 😀 HTLV-1 (Human T Cell Leukemia Lymphotropic Virus) affects 5 to 10 million people globally, primarily in regions like Japan, the Caribbean, Latin America, and parts of sub-Saharan Africa.
• 😀 Despite its widespread presence, HTLV-1 is not as well-known or researched as its cousin HIV.
• 😀 The virus was discovered in 1965 by Robert Gallo while studying leukemia cells at the NIH.
• 😀 HTLV-1 is a retrovirus that replicates by integrating its RNA into the host's DNA, leading to clonal expansion of infected T cells.
• 😀 The HTLV-1 genome is approximately 9,000 base pairs long and includes Long Terminal Repeats (LTRs) that play a crucial role in replication.
• 😀 HTLV-1 can cause severe diseases like Adult T-cell Leukemia/Lymphoma (ATL), a fatal cancer affecting about 5% of infected individuals.
• 😀 In addition to ATL, HTLV-1 is associated with inflammatory diseases like HTLV-1 Associated Myelopathy (HAM) or Tropical Spastic Paraparesis (TSP), which affect around 2% of infected individuals.
• 😀 HTLV-1 transmission requires direct cell-to-cell contact, making it primarily transmitted through vertical transmission (mother-to-child during breastfeeding), sexual contact, or unscreened blood products.
• 😀 The virus’s ability to integrate into the host’s DNA ensures the virus is stable, making it more difficult to detect and manage.
• 😀 HTLV-1’s impact is underreported due to its relatively low public awareness and the fact that it only causes severe diseases in a small percentage of infected individuals.

Q & A

What is HTLV-1 and how is it different from HIV?

HTLV-1, or Human T Cell Lymphotropic Virus, is a retrovirus that affects T cells, unlike HIV which primarily targets CD4+ T cells. HTLV-1 is less well-known and is not given as much attention in health agencies compared to HIV, but it affects millions globally.

Where is HTLV-1 most commonly found?

HTLV-1 is found in regions such as Japan, Latin America, the Caribbean, parts of sub-Saharan Africa, and central Australia, with high concentrations observed in certain areas like central Australia, where studies have shown that up to 45% of the adult population may be infected.

How was HTLV-1 discovered?

The discovery of HTLV-1 started in 1965 when researcher Gallo compared leukemia cells with normal leukocytes, using assays to study differences. The breakthrough came when retroviruses were found to cause cancer, leading to the identification of HTLV-1 as the first retrovirus linked to human cancer.

What is the significance of reverse transcriptase in the context of HTLV-1?

Reverse transcriptase, discovered by researchers including David Baltimore, allows retroviruses like HTLV-1 to convert RNA into DNA, which is then integrated into the host's genome. This enzyme plays a key role in detecting and studying retroviruses.

How does HTLV-1 replicate in human cells?

HTLV-1 replicates by first converting its RNA genome into double-stranded DNA, which is then integrated into the host's genomic DNA. The integrated viral DNA, or provirus, is transcribed to produce new viral particles and causes clonal expansion of infected T cells.

What are the key proteins involved in HTLV-1's oncogenic properties?

The two key proteins involved in HTLV-1's ability to cause cancer are the Tax protein, which acts as a transactivator of the viral LTR, and the HBZ (HTLV-1 bZIP factor), which is encoded in the antisense direction and also plays a role in oncogenesis.

What serious health conditions are associated with HTLV-1 infection?

HTLV-1 infection can lead to severe diseases such as Adult T-Cell Leukemia or Lymphoma (ATL), a fatal form of cancer, and HTLV-1-associated myelopathy (HAM) or tropical spastic paraparesis (TSP), a disease that causes inflammation and damage to the spinal neuronal cells.

How common are these severe diseases in HTLV-1 infected individuals?

Adult T-cell leukemia/lymphoma (ATL) occurs in about 5% of individuals infected with HTLV-1, while the inflammatory disease HAM/TSP affects around 2% of those infected.

How is HTLV-1 transmitted between individuals?

HTLV-1 is primarily spread through vertical transmission (from mother to child during breastfeeding), sexual contact, and through blood products that have not been properly screened for the virus.

Why is HTLV-1 often not as well-known as HIV despite its impact?

HTLV-1 is less well-known because it does not cause widespread disease in most individuals. Its more severe effects, like ATL, only affect a small percentage of those infected, which contributes to its lower visibility compared to HIV.