Used in immunological research to study T-cell activation and immune regulation in non-human primates. Enables detection and quantification of CD4+ T cells in flow cytometry and ELISA assays. Supports development of therapeutic antibodies and vaccines by serving as a control or standard in binding and neutralization studies. Facilitates investigation of HIV/SIV pathogenesis due to structural similarity to human CD4. The Fc tag allows for easy purification and detection using anti-Fc reagents, and can mediate effector functions in functional assays.