Schematic representation of the genome of the HAV-Bsd. The infectious cDNA of wild type HM-175 strain of HAV (wt HAV) containing a A216V amino acid substitution in the 2B protein was used as the background to construct HAV-Bsd. The blasticidin resistance (Bsd) gene coding for the blasticidin deaminase was inserted into the 2A-2B junction of the infectious cDNA of HAV . The Bsd gene was flanked by three G residues (gray box) and an HAV protease 3Cpro cleavage sites (dashed box) at each end. The three G residues form a hinge that facilitates the processing of the adjacent 3Cpro cleavage site and the release the blasticidin deaminase from the HAV polyprotein.