In this work, we describe the application of a genetically encoded glutathione biosensor comprising human glutaredoxin-1 linked to a redox-sensitive green fluorescent protein (Grx1-roGFP2) in accurately measuring glutathione redox potential (EGSH) (18) of cytosol and mitochondria of the HIV-1-infected monocytic cell line (U1) during different phases of infection. Here, GLRX is linked to infection.