The present invention concerns a modified nucleic acid molecule comprising a nucleotide sequence coding for a full length hepatitis C virus (HCV) glycoprotein selected from the group consisting of E1 glycoprotein and E1/E2 glycoprotein heterodimer, this molecule having at least one nucleotide alteration, wherein, due to this alteration, at least one RNA splice site selected from the group consisting of RNA splice acceptor and RNA splice donor sites is eliminated from the coding sequence. The invention is also directed to methods for expressing on the surface of a cell and a pseudovirion an HCV glycoprotein, wherein the majority of the glycoprotein is full length. The invention further provides a cell and a pseudovirion expressing such glycoprotein. The invention still further provides a method for determining whether an agent inhibits HCV fusion with and entry into a target cell. The invention also provides an agent that inhibits HCV fusion with and entry into a target cell. The invention further provides methods for treating a subject afflicted with an HCV-associated disorder, for preventing an HCV infection in a subject, and for inhibiting in a subject the onset of an HCV-associated disorder.