To create a hepatitis C virus uptake model, the part of exon 3 encoding extracellular loop 2 (EL2) was replaced with the equivalent part of exon 3 of the human orthologue. A loxP site flanked neomycin resistance gene cassette was inserted into human intron 3. This neo cassette was removed through subsequent cre-mediated recombination. (J:239318)