It was demonstrated that ORF2 and ORF3 are not involved in HEV cross-species infection, as evidenced by the failure of host range expansion of chimeric viruses in which the ORF2 or ORF3 gene was swapped [111,161], suggesting that other genomic regions (5′ UTR and ORF1) may play a role in determining the HEV host tropism. The gene discussed is ASZ1; the disease is infection.