CD4 receptor

Class

Post-attachment inhibitor (monoclonal antibody)

CD4 is a cell-surface glycoprotein found mainly on helper T lymphocytes, and at lower levels on monocytes, macrophages, and dendritic cells. Its normal role is to help stabilize interactions between T-cell receptors and antigen-presenting cells displaying MHC class II molecules, a step central to coordinating immune responses. CD4 is also the principal receptor that HIV-1 uses to enter human cells: the viral envelope glycoprotein gp120 binds CD4 as a first step in infection, followed by engagement of a co-receptor and membrane fusion. Because CD4 sits at this critical entry point, it has been targeted pharmacologically to block HIV from infecting new cells. Antibodies described as post-attachment inhibitors bind to CD4 at a site distinct from where gp120 attaches, allowing the virus to make initial contact but preventing the subsequent structural rearrangement required for productive entry. This approach is particularly relevant for individuals whose virus has become resistant to other classes of antiretroviral therapy, since it works through a mechanism unrelated to viral enzymes such as reverse transcriptase or protease. The broader disease relevance of CD4-targeted entry inhibition lies in chronic HIV infection, especially in treatment-experienced settings where few active options remain.