1. Cells with CD4 receptor on surface
T lymphocytes (T helper)
T-cell precursors in the bone marrow and thymus
Monocytes/macrophages
Dendritic cells (in the lymphatic organs, gut, genitourinary tract, submucosal tissue)
Microglia cells (in the central nervous system)
Retinal cells
Co-receptors: CCR5, CXCR4

3. Pathogenesis
HIV enters the susceptible cells, replicates and spreads in the body of the host.
Cell - mediated immunity is activated and kills the virus particles.
Specific antibodies are produces to fight the infection (humoral immunity).
Some viruses reach the reservoirs ( eg.lymph nodes, brain, urogenitary tract) and are safe from antibodies and killer cells.
The rate of replication gets established (set point).
HIV destroys T-lymphocytes (lysis, apoptosis),
new lymphocytes are being produced (balance).
T-lymphocytes count declines (immunodeficiency)

4. Surface pathogens Skin Streptococci, staphylococci Mucose membranes
Streptococci, staphylococci, candida sp.,
anaerobic bacteria (fusobacterium)
Pulmonary alveoli – cryptococci, Pneumocystis
carinii
GI tract – Escherichia coli
Saprofites are useful in immunocompetent patient.

5. Latent infections Early colonization of the body
Pathogen
Site of survival
HSV
VZV
EBV
CMV
Toxoplasma gondii
Dorsal root ganglia
” ” ”
Mucous membrane of the
mouth and throat – B lymphocytes
Macrophages
Tissue cysts in various organs

6. Sequelae of lymphocytes CD4 deficiency
Activation of surface pathogens
Candida albicans
Cryptococcus neoformans
Pneumocystis carinii
Reactivation of latent infections
Herpes simplex virus (HSV)
Varicella-zoster virus (VZV) - shingles
Cytomegalovirus (CMV)
Toxoplasma
Epstein – Barr virus (EBV)
Developing of neoplasms
Kaposi`s sarcoma
Non-Hodgkin`s lymphoma
Cervical carcinoma
Insufficient serologic response to new antigens
New infection – serologic diagnostic tests unreliable,
Vaccination – poor response (if any)

7. HIV / AIDS HIV infection ↓ Depletion of CD4 lymphocytes
Immunodeficiency
Opportunistic infections (reactivation)
Specific tumors