AIM: To develop a model of HIV disease progression. METHOD: Comparative analysis of viral burden and replication between peripheral blood and lymphoid organs and of the changes in viral distribution in the lymphoid tissue. RESULTS: In early-stage disease HIV-1-infected cells were sequestered in the lymphoid tissue, and the viral particles were concentrated and trapped in the germinal centers. The dichotomy in viral burden and viral replication between peripheral blood and lymphoid tissue was related to the histopathologic abnormalities associated with different stages of disease. CONCLUSIONS: These histopathologic abnormalities may not only explain the changes in viral distribution observed in the lymphoid tissue in different stages of the disease, but may also reflect different functional states of the immune system during the progression of HIV-1 infection from early- to late-stage disease.