Bone marrow stromal antigen 2

Bone marrow stromal antigen 2 (BST2) is an interferon-induced antiviral protein that acts as a physical tether to restrict the release of mammalian enveloped viruses, including HIV-1, influenza, SARS-CoV, and filoviruses (UniProt: Q10589). Beyond its antiviral function, BST2 regulates matrix metalloproteinase activity and modulates signaling in plasmacytoid dendritic cells. The protein exists in two functionally distinct isoforms with differing antiviral and NF-κB regulatory properties.

BST2 is expressed broadly across tissues with roles in viral restriction and innate immunity. UniProt records no primary disease associations, though its antiviral and immunomodulatory activities suggest potential relevance to infectious and inflammatory conditions.

In Alzheimer's disease, BST2 expression is significantly downregulated in post-mortem brain tissue compared to age-matched controls, with a mean log2 fold-change of −0.30 (Chaparral AD proteomics). This reduction was observed in a single subcellular fraction from a TMT-labeled proteomics study of four compartments. The functional significance of BST2 downregulation in AD pathology remains to be determined, though altered innate immune responses and viral restriction may contribute to neurodegeneration mechanisms.