CTSB and infection: Although pharmacological inhibition of cysteine cathepsins did not impact SFTSV entry, serine protease inhibitor AEBSF [4-(2-aminoethyl)-benzenesulfonylfluoride hydrochloride] significantly reduced SFTSV infection, suggesting that while cathepsins B and L are dispensable, serine proteases are critical for SFTSV entry (60) (Fig. 3C).