NS1 mutants in the hydrophobic protrusion deficient in viral replication can compensate for the role of ApoE in the infectious particle formation of HCV.

(A) Gene structure of a recombinant DENV with a luciferase gene and possessing a single amino-acid substitution in NS1 (F160A or V162D). (B) Luciferase activity was determined at 4, 24, and 48-h post-electroporation with the recombinant DENV RNA in BE-KO cells. (C) Experimental procedure. (D) Expression of ApoE and the wild type and mutant HA-tagged NS1 was determined by immunoblotting at 48-h post-transduction of lentiviruses into the BE-KO cells. Intracellular HCV RNA (E) and extracellular infectious titers (F) were determined at 72-h post-infection with JFH1 HCV at an MOI of 1 by qRT-PCR and focus-forming assay, respectively. In all cases, asterisks indicate significant differences (* p < 0.01) versus the results of the control cells.