Podcast
Questions and Answers
HTLV-1-associated myelopathy differs fundamentally from adult T-cell leukemia (ATLL) in what critical aspect?
HTLV-1-associated myelopathy differs fundamentally from adult T-cell leukemia (ATLL) in what critical aspect?
- It is directly caused by the cytopathic effects of HTLV-1 on neural tissue, leading to demyelination.
- It has a significantly shorter latency period compared to ATLL, typically presenting within 5 years of infection.
- It primarily affects CD8+ cytotoxic T lymphocytes, while ATLL involves CD4+ helper T lymphocytes.
- It manifests as a non-oncogenic neurological disease, unlike ATLL which is a malignancy. (correct)
Given the role of Tax and HBZ proteins in HTLV-1 infection, what therapeutic strategy would most directly target the virus's ability to induce cellular transformation?
Given the role of Tax and HBZ proteins in HTLV-1 infection, what therapeutic strategy would most directly target the virus's ability to induce cellular transformation?
- Employing monoclonal antibodies to neutralize HTLV-1 virions in the bloodstream, preventing further infection of CD4+ T cells.
- Using histone deacetylase inhibitors (HDACi) to promote the expression of tumor suppressor genes silenced by HTLV-1.
- Administering antiviral drugs that specifically inhibit the reverse transcriptase enzyme to prevent viral integration.
- Developing drugs that enhance the activity of HBZ, thereby suppressing Tax-mediated viral replication and cellular proliferation. (correct)
In the context of HTLV-1 transmission from mother to child, which intervention strategy would be LEAST effective in preventing viral spread?
In the context of HTLV-1 transmission from mother to child, which intervention strategy would be LEAST effective in preventing viral spread?
- Advising infected mothers to formula feed their infants as a complete substitute for breastfeeding.
- Encouraging infected mothers to express and pasteurize breast milk to eliminate cell-associated lymphocytes before feeding.
- Implementation of widespread screening for HTLV-1 antibodies in pregnant women, followed by counseling on the risks of breastfeeding.
- Cesarean delivery to prevent transmission via infected lymphocytes during vaginal birth. (correct)
What immunological mechanism is primarily responsible for controlling HTLV-1 infection, and what characteristic of infected cells facilitates this control?
What immunological mechanism is primarily responsible for controlling HTLV-1 infection, and what characteristic of infected cells facilitates this control?
Why are conventional cancer chemotherapeutic agents often ineffective in treating adult T-cell leukemia/lymphoma (ATL) induced by HTLV-1?
Why are conventional cancer chemotherapeutic agents often ineffective in treating adult T-cell leukemia/lymphoma (ATL) induced by HTLV-1?
Given that HTLV-1 integrates into the host genome, what is the MOST accurate implication for the infected individual?
Given that HTLV-1 integrates into the host genome, what is the MOST accurate implication for the infected individual?
A researcher aims to develop a diagnostic assay that can differentiate between HTLV-1 and HTLV-2 infections. Which approach would be MOST specific and reliable?
A researcher aims to develop a diagnostic assay that can differentiate between HTLV-1 and HTLV-2 infections. Which approach would be MOST specific and reliable?
A patient presents with cutaneous lesions, lymphadenopathy, and hepatosplenomegaly. Flow cytometry reveals a clonal population of CD4+ T cells with lobulated nuclei ('flower cells'). Which finding would be MOST indicative of HTLV-1-associated adult T-cell leukemia/lymphoma (ATL)?
A patient presents with cutaneous lesions, lymphadenopathy, and hepatosplenomegaly. Flow cytometry reveals a clonal population of CD4+ T cells with lobulated nuclei ('flower cells'). Which finding would be MOST indicative of HTLV-1-associated adult T-cell leukemia/lymphoma (ATL)?
In regions where HTLV-1 is endemic, what public health intervention would likely have the GREATEST impact on reducing the incidence of new infections?
In regions where HTLV-1 is endemic, what public health intervention would likely have the GREATEST impact on reducing the incidence of new infections?
Researchers discover a novel cellular protein that binds directly to the HTLV-1 Tax protein, preventing it from activating viral gene transcription. What is the MOST likely effect of this protein on HTLV-1 replication and pathogenesis?
Researchers discover a novel cellular protein that binds directly to the HTLV-1 Tax protein, preventing it from activating viral gene transcription. What is the MOST likely effect of this protein on HTLV-1 replication and pathogenesis?
Flashcards
HTLV
HTLV
A retrovirus family virus, icosahedral, enveloped, positive-strand, single-stranded RNA virus. Associated with leukemia, fluorescence, and CD4-positive T cells.
ATLL
ATLL
Adult acute T-cell lymphocytic leukemia, a human disease associated with HTLV-1, characterized by skin lesions.
HTLV-1 associated myelopathy
HTLV-1 associated myelopathy
A non-oncogenic, allergic disease associated with HTLV-1.
HTLV Tax Protein
HTLV Tax Protein
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HBZ
HBZ
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Flower Cells
Flower Cells
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ELISA
ELISA
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Cytotoxic T Lymphocytes (CTLs)
Cytotoxic T Lymphocytes (CTLs)
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RT-PCR
RT-PCR
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Study Notes
Human T-cell Lymphotropic Virus (HTLV)
- Part of the retrovirus family
- Features an icosahedral capsid and an envelope.
- Contains positive-sense, single-stranded RNA.
- Associated with leukemia and targets CD4-positive T cells.
- The first human retrovirus discovered.
- HTLV-1, -2, and -5 are human oncogenic viruses.
- HTLV-1 is definitively linked to adult acute T-cell lymphocytic leukemia (ATLL), characterized by skin lesions with a macular pattern, nodular patterns with papules, and erythroderma with scaly plaques.
- HTLV-1 is also associated with HTLV-1-associated myelopathy, a non-oncogenic neurological condition.
- HTLV-2 has been isolated from atypical forms of hairy cell leukemia.
- HTLV-5 has been isolated from a malignant cutaneous lymphoma.
- Cell-associated virus transmitted through infected lymphocytes.
- In endemic regions, transmission occurs from mother to fetus or newborn via the placenta or breast milk.
- Can be transmitted sexually via infected lymphocytes in semen.
- Can be transmitted through blood products containing intact cells.
- Targets CD4-positive lymphocytes.
- Increases the number of infected cells in vivo through the action of Tax and HBZ.
- The HTLV Tax protein is crucial for viral replication and initiating molecular transformation in ATLL development.
- A cellular protein, HBZ, limits Tax activity, promoting cell survival.
- After infection, the virus may remain latent or replicate slowly for years.
- Can induce the clonal outgrowth of particular T-cell clones
- There is a long latency period, around 30 years, before the onset of leukemia.
- HTLV-1-induced adult T-cell leukemia is usually monoclonal, despite the virus inducing a polyclonal outgrowth of T cells.
- The host immune response surfaces HTLV-1 infected cells mainly through lysis by virus-specific cytotoxic T lymphocytes (CTLs).
- HTLV-1-infected cells possess the immunophenotype of effector or memory T cells, which migrate into breast milk and semen.
- These infected cells can transfer infection to the new host.
- Between 5% and 10% of HTLV-1-infected individuals develop ATL or inflammatory diseases.
- Most HTLV-infected patients are asymptomatic but can progress to ATLL in 1 out of every 20 persons over a 30 - 50 year period.
- Nuclei of CD4-positive T helper cells in chronic medical cells are called "flower cells" because these cells contain lobulated nuclei.
- ATLL is characterized by skin lesions.
- The disease is usually fatal within a year of diagnosis, regardless of treatment.
Diagnosis and Treatment
- HTLV-1 infection is detected using ELISA to identify specific viral antigens and antibodies in the blood.
- RT-PCR can be used to detect viral DNA.
- Usual agents used in cancer chemotherapy have proven to be ineffective in treating adult T-cell leukemia.
- Treatment focuses on the symptoms of associated diseases.
- Prevention of HTLV infection includes following safe sex practices, screening blood donors, and avoiding needle sharing.
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