Podcast
Questions and Answers
HHV-6's ability to establish latency in monocytes poses the greatest risk of severe complications in which patient population?
HHV-6's ability to establish latency in monocytes poses the greatest risk of severe complications in which patient population?
- Otherwise healthy children between 6 months and 2 years of age.
- Adults with a history of recurrent bacterial pneumonia.
- Immunocompromised adults post-organ transplant. (correct)
- Adolescents experiencing primary Epstein-Barr virus infection.
What is the most likely mechanism by which HHV-8 promotes oncogenesis in Kaposi's sarcoma?
What is the most likely mechanism by which HHV-8 promotes oncogenesis in Kaposi's sarcoma?
- Directly integrating its viral genome into the host cell's DNA, causing mutations in proto-oncogenes.
- Expressing the latency-associated nuclear antigen (LANA-1), which inhibits the p53 tumor suppressor protein and prevents apoptosis (correct)
- Stimulating the excessive production of growth factors, leading to uncontrolled proliferation of endothelial cells.
- Inducing chronic inflammation, leading to the production of reactive oxygen species that damage cellular DNA.
A clinician suspects roseola infantum in a 9-month-old infant. Which clinical finding would be most indicative of this diagnosis, differentiating it from other common childhood viral exanthems?
A clinician suspects roseola infantum in a 9-month-old infant. Which clinical finding would be most indicative of this diagnosis, differentiating it from other common childhood viral exanthems?
- The presence of Koplik spots on the buccal mucosa.
- A vesicular rash distributed along a dermatome.
- Nagayama spots on the soft palate and uvula. (correct)
- A sandpaper-like rash accompanied by a strawberry tongue.
In a patient diagnosed with AIDS-associated Kaposi's sarcoma, what immunological deficiency most directly contributes to the reactivation and aggressive progression of HHV-8?
In a patient diagnosed with AIDS-associated Kaposi's sarcoma, what immunological deficiency most directly contributes to the reactivation and aggressive progression of HHV-8?
Why is HHV-6 able to disseminate widely throughout the body following initial infection?
Why is HHV-6 able to disseminate widely throughout the body following initial infection?
A researcher is studying the impact of HHV-8 infection on endothelial cell function. What cellular process would be most directly affected by the expression of LANA-1?
A researcher is studying the impact of HHV-8 infection on endothelial cell function. What cellular process would be most directly affected by the expression of LANA-1?
A patient presents with violaceous skin lesions suspected to be Kaposi's sarcoma. If immunohistochemical staining of a biopsy sample is positive, which specific viral antigen confirms the diagnosis of HHV-8 infection?
A patient presents with violaceous skin lesions suspected to be Kaposi's sarcoma. If immunohistochemical staining of a biopsy sample is positive, which specific viral antigen confirms the diagnosis of HHV-8 infection?
What feature of the HHV-8 viral lifecycle allows it to persist in the host and cause Kaposi's sarcoma even when the host immune system is partially functional?
What feature of the HHV-8 viral lifecycle allows it to persist in the host and cause Kaposi's sarcoma even when the host immune system is partially functional?
Why do antiviral treatments like acyclovir, typically used for herpes simplex virus infections, often show limited efficacy against HHV-6 and HHV-8?
Why do antiviral treatments like acyclovir, typically used for herpes simplex virus infections, often show limited efficacy against HHV-6 and HHV-8?
A researcher aims to develop a novel therapeutic strategy targeting HHV-6. Which of the following approaches would be most likely to prevent viral replication in CD4+ T lymphocytes during the lytic cycle?
A researcher aims to develop a novel therapeutic strategy targeting HHV-6. Which of the following approaches would be most likely to prevent viral replication in CD4+ T lymphocytes during the lytic cycle?
Flashcards
HHV-6
HHV-6
A double-stranded linear DNA virus transmitted via respiratory secretions, causing roseola infantum.
Roseola Infantum
Roseola Infantum
Common childhood disease caused by HHV-6, featuring high fever followed by a maculopapular rash.
Nagayama Spots
Nagayama Spots
Erythematous papules on the soft palate and uvula seen in roseola infantum.
HHV-8
HHV-8
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Oncovirus
Oncovirus
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Latency-Associated Nuclear Antigen (LANA-1)
Latency-Associated Nuclear Antigen (LANA-1)
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Kaposi's Sarcoma
Kaposi's Sarcoma
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Study Notes
- Human Herpes Virus 6 (HHV-6) and Human Herpes Virus 8 (HHV-8) are double-stranded linear DNA viruses.
HHV-6
- Belongs to the Herpesviridae family, subfamily Betaherpesvirinae, genus Roseolovirus
- Respiratory secretions transmit HHV-6
- The virus attaches to dendritic cells, which present antigens to T cells.
- HHV-6 migrates to lymph nodes, infecting CD4+ T lymphocytes, where it replicates efficiently undergoing the lytic cycle within T cells, producing new viruses that destroy the cell and infect neighboring cells
- HHV-6 replicates less efficiently in monocytes, macrophages, NK cells, astrocytes, megakaryocytes, and glial cells
- HHV-6 enters a latent state in monocytes and can reactivate in immunocompromised individuals, causing serious infections like encephalitis
- Primary infection causes roseola infantum, also known as exanthem subitum or sixth disease
- Roseola infantum is common in children aged 6 months to 2 years, with an incubation period of 1-2 weeks
- Symptoms of roseola infantum include high fever (up to 40°C or 104°F) lasting 3-5 days, peri-orbital edema, acute otitis media, rhinorrhea, cough, vomiting, diarrhea, bulging fontanelle, lymphadenopathy, and Nagayama spots (erythematous papules on the soft palate and uvula)
- A maculopapular rash appears on the neck, trunk, face, and extremities after the fever subsides, lasting a few hours to two days
Diagnosing HHV-6
- Clinical findings, PCR to identify viral DNA, and serological tests for IgG antibodies against HHV-6 are methods of diagnosis
Treatment for HHV-6
- Supportive care (antipyretics like acetaminophen or ibuprofen, increased fluid intake)
- Antivirals like acyclovir or ganciclovir in severe cases (immunocompromised individuals) can be used
HHV-8
- HHV-8 is also called Kaposi's sarcoma-associated herpesvirus (KSHV)
- Belongs to the family of human gammaherpesviruses
- HHV-8 is one of the seven known oncoviruses (cancer-causing viruses), specifically causing Kaposi's sarcoma (KS).
- The virus is a large, double-stranded linear DNA virus surrounded by an icosahedral capsid, a protein layer called the tegument, and an envelope with viral glycoproteins
- Transmitted through sexual contact
- HHV-8 enters B cells, endothelial cells, macrophages, and epithelial cells
- During the Latent Phase, the virus remains in the cell without destroying it and expresses the latency-associated nuclear antigen (LANA-1), inhibiting tumor suppressor protein p53, preventing apoptosis, leading to uncontrolled cellular proliferation
- During the Lytic Phase, the virus replicates, producing new viruses that destroy the cell and infect neighboring cells
- Infection is rare in individuals with healthy immune systems due to humoral (antibodies) and cellular (cytotoxic T cells) immune responses
- Immunocompromised individuals (AIDS, organ transplant recipients, immunosuppressive medications) are at higher risk
Kaposi's Sarcoma Types
- Classic
- Endemic
- Epidemic (AIDS-associated)
- Immunosuppression therapy-related
Kaposi's Sarcoma Symptoms
- Characterized by vascular proliferation and dark or violaceous plaques on the skin, mouth, GI tract, or lungs
- Red or purple skin lesions resembling bruises, which can grow into nodules and merge
- Weight loss, nausea, vomiting, diarrhea, bleeding, malabsorption
- Shortness of breath, chest pain, cough, hemoptysis
Diagnosing HHV-8
- Biopsy of lesions, microscopic examination showing spindle cells, immunohistochemical staining for LANA-1, and PCR for viral DNA
Treatment for HHV-8
- Treatments are aimed at stopping the progression of KS
- Local treatments (radiation therapy, cryosurgery) for skin lesions
- Chemotherapy (doxorubicin, daunorubicin, thalidomide, paclitaxel) for widespread disease
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