293 cells over‐expressing human ADI1 and CD81 are permissive for serum‐derived hepatitis C virus infection

Human aci‐reductone dioxygenase 1 (ADI1) is a member of the Cupin superfamily. It binds to and inhibits the activities of membrane‐type 1 matrix metalloproteinase, a protein known to interact with the tight junction protein, claudin‐1. Previously, a variant protein, named submergence‐induced protein‐like factor (Sip‐L), consisting of ADI1 amino acids 64–179, was found to support hepatitis C virus (HCV) infection and replication in 293 cells. In the present study, it was discovered that over‐expression of human ADI1 in 293 cells (293‐ADI1 cells) also supported HCV infection and replication. Using serum‐derived HCV as an infectious source, enhanced cell uptake of HCV to a Northern blot detectable level was found in 293 cells over‐expressing both CD81 and ADI1 (293‐ADI1‐CD81 cells). The enhanced cell entry was confirmed by the use of the vesicular stomatitis virus‐based HCV pseudotype particles. However, transfection of HCV replicon RNA by electroporation into naïve 293 and 293‐ADI1 cells revealed no difference in replication efficiency. Using the infectious J6/JFH chimera as an infectious source, the infectivity was compared between 293‐ADI1‐CD81 and Huh‐7.5 cells. More infection foci were formed in the 293‐ADI1‐CD81 cells in the first round of infection. In conclusion, human ADI1 over‐expression in 293 cells enhances cell entry but not replication of HCV. 293‐ADI1‐CD81 cells are permissive for serum‐derived HCV infection. J. Med. Virol. 81:1560–1568, 2009. © 2009 Wiley‐Liss, Inc.