Flavivirus NS1 can compensate for the role of apolipoproteins in the infectious particle formation of HCV.

(A) Gene structures of flavivirus and hepacivirus and the experimental procedure. (B) Expression of ApoE and HA-tagged NS1 (HA-NS1) from serotypes 1 to 4 of DENV was determined by immunoblotting at 48-h post-transduction of lentiviruses into the BE-KO cells. Intracellular HCV RNA (C) and extracellular infectious titers (D) were determined at 72-h post-infection with JFH1 HCV at an MOI of 1 by qRT-PCR and focus-forming assay, respectively. (E) Expression of ApoE and HA-NS1 from DENV, JEV, TBEV, and Yokose virus was determined by immunoblotting at 48-h post-transduction of lentiviruses into the BE-KO cells. Intracellular HCV RNA (F) and extracellular infectious titers (G) were determined at 72-h post-infection with JFH1 HCV at an MOI of 1 by qRT-PCR and focus-forming assay, respectively. (H) Expression of ApoE and HA-NS1 from DENV and JEV in 293T/CLDN1/miR-122 cells was determined by immunoblotting analysis. Cells were infected with HCV at an MOI of 10, and intracellular HCV RNA (I) and infectious titers in the supernatants (J) at 72-h post-infection were determined 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.