Consistently, depletion of host proteins associated with late endosome and late endosome-to-lysosome maturation (RAB7A, RAB7B, and the HOPS complex subunits VPS11, VPS33A, VPS39 and VPS41) or addition of U18666A, which blocks late endosome-to-lysosome trafficking, were shown to inhibit both infection and virus-cell fusion. The gene discussed is VPS39; the disease is infection.