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تسجيل

Role of Receptors and Co-receptors in HIV Pathogenesis

المؤلف:  Baijayantimala Mishra

المصدر:  Textbook of Medical Virology

الجزء والصفحة:  2nd Edition , p252-253

2025-12-06

586

CD4, a 58 KDa monomeric glycoprotein, expressed on the surface of T lymphocytes, monocytes, macrophages, dendritic cells, eosinophils. It serves as the principal receptor for HIV. Binding of HIV gp 120 occurs within its V2 region. Apart from CD4, HIV utilizes either one of the co-receptors CCR-5 or CXCR-4. CCR-5 and CXCR-4 (fusin) belong to certain endogenous chemokine receptor families. RANTES (regulated on activation, normal T cell expressed and secreted) or chemokine (C-C motif) ligand 5 (CCCL5), macrophage inflammatory proteins (MIP) 1a and b are the natural ligands for CCR-5. Stromal cell-derived factor 1 (SDF1), also known as C-X-C motif chemokine 12 (CXCL12), is the natural ligand for CXCR-4. HIV isolates are classified as either T-tropic (X4 viruses) if they utilize CXCR 4 as the major co-receptor or M-tropic (R5 viruses) if they utilize CCR5 as the major co-receptor. The co-receptor tropism is partly explained by the affinity of the third variable region (v3 loop) of gp120 to either CCR-5 or CXCR -4. R5 viruses predominate in the early phase of the diseases, and there is transition to X4 viruses as the disease progresses.

The pathogenesis of HIV is a complex interplay of viral and host immunologic events and varies during different stages of the disease process. The typical course of an untreated HIV-infected individual can be broadly subdivided into primary infection, clinical latency and finally advanced disease. The pathogenic events during various stages of the disease are described below.