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. FcαRI (Fc fragment of IgA receptor), also referred to FcalphaRI or CD89, is the most prominent and only human immunoglobulin A (IgA) Fc receptor that binds the heavy-chain constant region of IgA via two extracellular binding sites. This receptor is a transmembrane glycoprotein mapping at the chromosome 19q13.42 and belongs to the immunoglobulin (Ig) gene superfamily. FcαRI is expressed on the surface of blood myeloid cells, such as monocyte/macrophages, neutrophils, eosinophils, dendritic cells, and Kupffer cells, in which it mediates immunologic responses to pathogens. IgA plays an important role in immune protection. It interacts with IgA-opsonized targets and initiates a number of immunologic defense processes, for instance, phagocytosis, stimulation of the release of inflammatory mediators, and antibody-dependent cell-mediated cytotoxicity.