To explore the role of ORF4 in HEV-1 replication and infection, we cloned the complete genome of wild-type HEV-1 downstream of a T7 RNA polymerase promoter, and the following ORF4 mutant constructs were prepared: the first construct had TTG instead of the initiation codon ATG (A2836T), introducing an M→L mutation in ORF4 and a D→V mutation in ORF1. Here, CTTNBP2 is linked to infection.