We have previously reported that a membrane unpermeable cathepsin L inhibitor, CLIK148, attenuates the Eco-MLV infection at 1000 μM [14], suggesting that much higher concentration of the unpermeable cathepsin inhibitor III is required for inhibition of the Eco-MLV vector infection than the permeable cathepsin inhibitor CA-074Me. The gene discussed is CTSS; the disease is infection.