The amino acids 157 to 165 of NTCP were found to be critical for viral entry and viral infection in other species since their substitution with the corresponding human NTCP residues converted crab-eating/cynomolgus macaque (macaca fascicularis) NTCP (which shares a 96.3% protein identity with human NTCP) into a functional receptor for pre-S1 binding and allowed HDV infection in vitro [39,49]. This evidence concerns the gene SLC10A1 and viral infectious disease.