Question

Kaposi sarcoma is caused by which of the following?

• A. Human Herpesvirus 6 (HHV-6)
• B. Human Herpesvirus 8 (HHV-8)
• C. Epstein-Barr Virus (EBV)
• D. Human Papillomavirus (HPV)

Hint:

Recall which herpesvirus is specifically associated with the most common AIDS-defining malignancy presenting as purplish skin lesions.

Answer 1

The Correct Option is B

Step 1: What is Kaposi sarcoma? Kaposi sarcoma (KS) is a vascular tumour that most commonly presents as purplish skin lesions. It is the most common AIDS-defining malignancy and occurs in HIV-positive individuals with severe immunosuppression (CD4 count < 200 cells/microlitre).

Step 2: Causative agent. Kaposi sarcoma is caused by Human Herpesvirus 8 (HHV-8), also known as Kaposi Sarcoma-associated Herpesvirus (KSHV). HHV-8 is a gamma-herpesvirus (subfamily Gammaherpesvirinae), related to EBV.

Step 3: Pathogenesis of HHV-8. HHV-8 infects endothelial cells and B lymphocytes. It encodes oncogenic proteins including viral FLICE inhibitory protein (vFLIP), viral cyclin D, and viral interleukin-6. These proteins inhibit apoptosis, promote cell proliferation, and stimulate angiogenesis, leading to tumour formation.

Step 4: Exclusion of other options.
- HHV-6: causes roseola infantum (exanthem subitum)
- EBV (HHV-4): causes Burkitt lymphoma, nasopharyngeal carcinoma, infectious mononucleosis
- HPV: causes cervical carcinoma, genital warts, head and neck cancers

Conclusion: Kaposi sarcoma is caused by Human Herpesvirus 8 (HHV-8 / KSHV).