In addition, the mutation in the putative second start cordon (nt 2854–2856) alone and simultaneous mutations with the first start codon (nt 2836–2838) did not affect the replication or infection in vitro, demonstrating that this putative smaller ORF4 is also not essential for HEV-1 replication and infection in vitro. This evidence concerns the gene CTTNBP2 and infection.