Development of a Virus Particle-Based Antibody-Dependent Cellular Phagocytosis (ADCP) Assay for HIV

Antibody-dependent cellular phagocytosis (ADCP) is an Fc-mediated effector function that contributes to the clearance of pathogens, including HIV. Conventional bead-based ADCP assays using recombinant Env proteins provide valuable insights but do not recapitulate the structural and antigenic complexity of intact virions, potentially limiting their physiological relevance. Here, we describe a virus particle-based ADCP assay that preserves the native conformation and glycosylation of the HIV envelope glycoprotein (Env), features critical for antibody recognition and Fcγ receptor engagement. The assay utilizes THP-1 monocyte-derived cells as effector cells and sucrose purified HIV-1 virions coupled with fluorescent beads, as targets. This platform enables sensitive and reproducible measurement of antibody-mediated phagocytosis in a biologically relevant context, facilitating accurate assessment of Fc effector functions across monoclonal and polyclonal antibody samples from multiple species. The approach addresses key limitations of traditional assays and provides a scalable tool for evaluating humoral immunity in HIV infection and vaccine studies.