HHV-6 Induced Immune Suppression

Recent evidence demonstrates that HHV-6 (especially HHV-6A) can cause selective immunosuppression in otherwise in immunocompetent adults. HHV-6 infection can:

• Deplete CD4 T lymphocytes via direct infection and induction of apoptosis. (Grivel 2003)
  
• Cause a delay maturation of dendrocytes. (Lusso 2005)
  
• Disturb key immune activation pathways and cytokine networks including an upregulation of TNF alpha, TNF- gamma, IL-1beta and IL-10. (Flamand 1996,Dockerell 2004, Li 1998) (Smith 2005 2004)
  
• Downregulate complement activity through the CD46 receptor and downregulation of Il-2. (Russell 2004) (Grivel 2003)
  
• Suppress the ability of macrophages to produce  IL-12p70  upon stimulation with interferon gamma. (Smith 2005)

HHV-6 invades the CD4 cells, adversely affecting function. HHV-6A, but not HHV-6B also invades CD8 cells.