Constructed preS2 mutants and their sensitivity to antiviral drugs. Two deletions illustrated at the top were introduced into the wt genome in a plasmid, respectively. Constructed mutants were transfected into Huh7 cells with or without antiviral drug treatment as indicated in each plot. The viral replication level in a culture medium without drugs was denoted as 100%. The curves indicate the decrease in viral replication with increasing drug concentrations and the preS2 deletion alone did not change the mutants’ sensitivity to antiviral drugs. The crossover points between the horizontal line and the curves indicate the IC50 for each strain. *similar viral replication data of the Δ2 mutant with drug treatment is shown in Additional file 1: Figure S1.