Effects of HIV infection on the immune system
Cells Harbor HIV as a Silent Provirus for long periods
• HIV Virus is protected from immune system attacks until the virus is stimulated to multiply and display viral antigens.
Cells Harbor HIV as a Silent Provirus for long periods
▪ A provirus is a virus genome that is integrated into the DNA of the host cell and in the proviral state.
Damage to Lymphoid Tissues
▪ Can be seen in late HIV infection.
CD4 T Helper Cells
▪ Decreased CD4 cells in the hallmark of HIV infection.
Other Immunologic Abnormalities
▪ Decreased NK cell activity.
Other Immunologic Abnormalities
▪ Defective antigen presentation and oxidative burst by the monocytes and macrophages.
Gastrointestinal Immune System (GALT)
▪ HIV causes a rapid depletion of CCR5, CD4 memory T cells in the GALT
Th17 Helper Cells
▪ Impaired function in HIV patients.
Gastrointestinal Immune System (GALT)
▪ Largest immune organ in the body
Damage to Lymphoid Tissues
▪ Loss of germinal centers and follicular dendritic cells results in the inability to activate T and B lymphocytes.
Downregulate Production of Class 1 MHC Molecules on the surface of host cells
▪ Making it difficult for CTL to recognize infected cells.
Gastrointestinal Immune System (GALT)
▪ Most affected immune organ.
CD4 T Helper Cells
▪ Most severely affected cells
Ineffective Immune Response
▪ Not enough to completely eliminate virus
CD4 T Helper Cells
▪ Plays a central role in the immune system by regulating B and T lymphocyte activity, thus destruction of these cells results in decrease effectiveness of both Antibody and Cell Mediated Immune response.
Th17 Helper Cells
▪ Plays an important role in homeostasis of the epithelial cell lining of the intestinal mucosa in the secretion of antimicrobial defenses.
Downregulate Production of Class 1 MHC Molecules on the surface of host cells
▪ Protected from CTL recognition.
Cells Harbor HIV as a Silent Provirus for long periods
▪ These cells include resting CD4 T cells, dendritic cells, cells of monocyte and macrophage lineage, and microglial cells.
Th17 Helper Cells
▪ This depletion results to the damage to intestinal barrier and leakage of lipopolysaccharides into the plasma
CD4 T Helper Cells
▪ Thought to be killed and made non-functional by HIV.
Ineffective Immune Response
▪ Virus undergoes rapid genetic mutations which creates an escape? mutants with altered antigens towards which the host immune responses are ineffective.