FcγRI, synonymously also referred to CD64, is a membrane spanning protein of 72 kDa and belongs to the immunoglobulin (Ig) supergene family. It has three extracellular Ig-like domains and is the only receptor that can efficiently bind monomeric IgG and aggregated IgG17. Hence, FcγRI is known to functions as a high-affinity Fcγ receptor where exists other two members FcγRII (CD32) and FcγRIII (CD16), but with low affinity. In humans, FcγRI is constitutively expressed on monocytes/macrophages, myeloid precursors, as well as follicular dendritic cells and its expression can also be induced on polymorphonuclear neutrophils via IFN-γ or G-CSF. Now, FcγRI is considered a great monocyte/macrophage-associated marker, normally used in flow cytometry (FCM) to identify leukemias with myelomonocytic differentiation. Gp41 (Glycoprotein 41) is a subunit of the envelope protein complex of human immunodeficiency virus (HIV), which plays an important role in virus entry. The transmembrane submit protein gp41 with surface subunit gp120 make up the glycoprotein env of HIV, when non-covalently bound to each other (Envelope spike complex). There are three major regions within the gp41 sequence including the cytoplasm domain, the transmembrane domain, and the ectodomain. Its ectodomain contains certain sites required for the infection of host cells. Furthermore, gp41 has two structures of helical repeats that are essential for the viral fusion, heptad repeat 1 (HR1) and heptad repeat 2 (HR2). Since it is crucial in the HIV infection process, gp41 has emerged as an attractive target for drug design.