CTSB and infection: Compared to cells infected in the absence of inhibitor (Fig 1, infected bar), we observed a 61.45% decrease in infection the presence of NH4Cl (Fig 1, NH4Cl bar), a 41.38% and 37.30% decrease in the presence of permeable and non-permeable broad targeting cysteine protease inhibitors (Fig. 1, E64 and E64-d bar, respectively), and a statistically significant decrease in infectivity of 53.75% and 51.11% in the presence of specific cathepsin B or cathepsin L inhibitors (Fig 1 cathepsin B and cathepsin L bars respectively) (p < 0.05 1-tail t test).