Medicine & USMLE

Human Herpesviruses 8 (HHV8)

Viruses - DNA Viruses
  1. Herpesvirus Overview
  2. Herpes Simplex Virus 1 (HSV1)
  3. Herpes Simplex Virus 2 (HSV2)
  4. Varicella-Zoster Virus (HHV3)
  5. Epstein-Barr Virus (HHV4)
  6. Cytomegalovirus (HHV5)
  7. Human Herpesviruses 6 and 7 (HHV6 and HHV7)
  8. Human Herpesviruses 8 (HHV8)
  9. Poxvirus
  10. Hepadnavirus
  11. Adenovirus
  12. Papillomavirus (HPV)
  13. Polyomavirus
  14. Parvovirus

Key Points

  • Human herpesvirus 8 (HHV-8)
    • Characteristics
      • Member of Herpesvirus family
        • Enveloped DNA virus with double-stranded, linear DNA 
          • Herpesviruses are unique in that they get their envelope by budding from nuclear membrane of host cell
    • Transmission
      • Endemic in Africa and Sardinia
      • Unclear route of transmission
        • Sexual contact and saliva may be modes of transmission
    • Pathogenesis
      • Infects many cell types (e.g. B cells, endothelial cells, macrophages, and epithelial cells)
      • Can cause latent infection (like other herpesviruses)
        • Reactivation may lead to some forms of Kaposi’s sarcoma (below)
      • HHV-8 inhibits tumor suppression pathways
    • Presentation
      • Primary infection (viremia) may present as non-specific fever and rash
      • Kaposi Sarcoma (KS)
        • Seen in immunocompromised patients
          • especially AIDS and solid organ transplant recipients
        • Cancer of blood vessels
        • Discolored skin lesions
          • Dark blue/red/purple/violet/brown colored macules, plaques or nodules
            • Colors from blood vessels with hemorrhage/hemosiderin deposition
            • Variance of color depends on vascularity of lesion
          • Affects skin, oral or genital mucous membranes, GI tract, or lung
          • Associated with lymphedema
      • May also present with B symptoms (fever, night sweats, and weight loss)
        • Results from chronic inflammation (inflammatory cytokine syndrome)
        • Elevated levels of cytokines are seen
      • Also linked with Primary effusion lymphoma (PEL) and Castleman disease
    • Diagnosis
      • PCR can confirm presence of HHV-8
      • Histopathology of Kaposi’s Sarcoma
        • Whorls of spindle cells
        • Vessel proliferation (neovascularization)
          • Microhemorrhages with hemosiderin deposition may be seen due to leaky capillaries
        • Leukocytic proliferation
    • Treatment
      • Treatment of HHV-8 is poorly understood
        • HAART in AIDS-related disease
        • Local or systemic chemotherapy depending on severity of disease
        • Interferons may hold some utility