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Questions and Answers
Which of the following mechanisms primarily drives the transmission of Human T-cell Lymphotropic Virus Type 1 (HTLV-1) in highly endemic regions?
Which of the following mechanisms primarily drives the transmission of Human T-cell Lymphotropic Virus Type 1 (HTLV-1) in highly endemic regions?
- Direct inoculation via shared intravenous needles contaminated with infected blood.
- Sexual transmission through direct contact with infected bodily fluids.
- Transplacental transfer or breastfeeding involving infected lymphocytes. (correct)
- Respiratory droplets containing cell-free viral particles.
How does the Human T-cell Lymphotropic Virus type 1 (HTLV-1) induce the formation of Adult T-cell Leukemia/Lymphoma (ATLL)?
How does the Human T-cell Lymphotropic Virus type 1 (HTLV-1) induce the formation of Adult T-cell Leukemia/Lymphoma (ATLL)?
- Through the Tax protein, which promotes proliferation and reduces apoptosis in infected CD4+ T cells, leading to uncontrolled growth. (correct)
- Integration of the viral genome followed by immediate host cell lysis, releasing viral particles into the bloodstream to infect new cells.
- Direct infection of cytotoxic T cells, causing immunosuppression and secondary opportunistic infections rather than neoplastic transformation.
- By inducing a chronic inflammatory response mediated by B cells producing auto-antibodies against T cell surface proteins.
What cellular characteristic is most indicative of Adult T-cell Leukemia/Lymphoma (ATLL) in a patient's peripheral blood smear?
What cellular characteristic is most indicative of Adult T-cell Leukemia/Lymphoma (ATLL) in a patient's peripheral blood smear?
- Increased presence of Reed-Sternberg cells showing bilobed or multi-lobulated nuclei.
- Atypical lymphocytes with highly lobulated, pleomorphic nuclei resembling "flower cells." (correct)
- Numerous plasma cells exhibiting eccentric nuclei and perinuclear halos.
- Elevated number of basophils displaying metachromatic granules.
What is the primary mechanism by which cytotoxic T lymphocytes (CTLs) attempt to control Human T-cell Lymphotropic Virus Type 1 (HTLV-1) infection?
What is the primary mechanism by which cytotoxic T lymphocytes (CTLs) attempt to control Human T-cell Lymphotropic Virus Type 1 (HTLV-1) infection?
What accounts for the typical ineffectiveness of standard chemotherapy regimens in treating Adult T-cell Leukemia/Lymphoma (ATLL) caused by HTLV-1?
What accounts for the typical ineffectiveness of standard chemotherapy regimens in treating Adult T-cell Leukemia/Lymphoma (ATLL) caused by HTLV-1?
What diagnostic approach offers the most comprehensive method for confirming HTLV-1 infection, especially in individuals with ambiguous ELISA results?
What diagnostic approach offers the most comprehensive method for confirming HTLV-1 infection, especially in individuals with ambiguous ELISA results?
What is the main role of the HBZ protein produced by the host cell in the context of HTLV-1 infection?
What is the main role of the HBZ protein produced by the host cell in the context of HTLV-1 infection?
In the pathogenesis of HTLV-1 associated myelopathy/tropical spastic paraparesis (HAM/TSP), what is the most likely mechanism of neuronal damage?
In the pathogenesis of HTLV-1 associated myelopathy/tropical spastic paraparesis (HAM/TSP), what is the most likely mechanism of neuronal damage?
What is a key public health strategy for preventing the spread of HTLV-1 via blood transfusions?
What is a key public health strategy for preventing the spread of HTLV-1 via blood transfusions?
What distinguishes HTLV-2-related hairy cell leukemia from the classical form of hairy cell leukemia?
What distinguishes HTLV-2-related hairy cell leukemia from the classical form of hairy cell leukemia?
Flashcards
HTLV Characteristics
HTLV Characteristics
Retrovirus family member with single-stranded, positive-sense RNA, an envelope, and an icosahedral capsid. Includes oncovirus strains like HTLV-1, 2, and 5.
HTLV-1 Diseases
HTLV-1 Diseases
HTLV-1 causes adult acute T-cell lymphocytic leukemia (ATLL), characterized by skin lesions, and HTLV-1-associated myelopathy (HAM/TSP), a neurological disease.
HTLV Transmission
HTLV Transmission
In endemic regions, it spreads from mother to child transplacentally or via breast milk; also via infected lymphocytes through sex (HTLV-2) or blood products (HTLV-3).
HTLV Target Cells
HTLV Target Cells
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"Flower Cells"
"Flower Cells"
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HTLV Diagnosis
HTLV Diagnosis
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HTLV and CD4+ T Cells
HTLV and CD4+ T Cells
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Maculopapular Rash and Scales via HTLV-1
Maculopapular Rash and Scales via HTLV-1
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Study Notes
- Human T cell lymphotropic virus (HTLV) is a retrovirus belonging to the Retroviridae family.
- It is a single-stranded, positive-sense RNA virus with an envelope and an icosahedral capsid.
- HTLV is an oncovirus, with types 1, 2, and 5 identified, although only HTLV-1 is definitively linked to human diseases.
Diseases Caused by HTLV
- HTLV-1 causes adult acute T-cell lymphocytic leukemia (ATLL), characterized by specific skin lesions, and HTLV-1-associated myelopathy, a neurological disease.
- HTLV-2 leads to atypical forms of hairy cell leukemia.
- HTLV-5 has been isolated from a malignant cutaneous lymphoma.
HTLV Transmission
- Transmission occurs in highly endemic regions from mother to child via placental transfer or breast milk.
- The virus transmits through infected lymphocytes, not freely in blood like other viruses.
- HTLV-2 transmits sexually through infected lymphocytes in semen, and HTLV-3 transmits via blood products containing intact cells.
Pathogenesis and Symptoms
- HTLV targets CD4 lymphocytes, including dendritic cells, CD4+ T cells, or macrophages.
- Infections are often asymptomatic but can progress to ATLL in about 5% of those infected over 30-50 years.
- Malignant T-helper cells in ATLL display lobulated and pleomorphic nuclei, known as "flower cells".
- ATLL is generally fatal within a year of diagnosis, irrespective of treatment.
Diagnosis and Treatment
- Diagnosis involves ELISA to detect specific viral antigens and antiviral antibodies, along with RT-PCR for viral DNA.
- Treatment mainly focuses on symptom management, as chemotherapy is typically ineffective.
- Prevention strategies include practicing safe sex and screening blood products.
Immune Response and Viral Mechanisms
- Cytotoxic T lymphocytes target and destroy HTLV-1 infected cells, causing lysis.
- The immune response to infected T cells leads to maculopapular rashes and scales on the skin.
- After infection, the virus increases the number of infected cells via Tax protein to replicate and cause cancer, while the HBZ protein from the host cell attempts to limit Tax activity.
- HTLV causes abnormal growth and proliferation of CD4+ T cells, leading to neoplasia that can be acute or chronic.
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