Evidence of transmission of hepatitis D virus to spouses from sequence analysis of the viral genome

To study sexual transmission of hepatitis D virus (HDV), 52 spouses of 56 index patients were observed and HDV genomes from antibody to HDV (anti‐HDV)‐positive couples were sequenced. Of the spouses, 11 (21%) were serum HBsAg positive, 3 (27%) of whom were also anti‐HDV positive. The HDV sequences between spouses were found to be nearly identical (98% to 98.8%) in the region analyzed (nt 911 to nt 1260). Only one couple showed an identity >90% with the genotype I HDV strains. The HDV sequences of the remaining two couples showed >95% identity with each other and >91% homology with genotype II, but they shared only a 73.1% to 73.7% homology with those of the first couple. The regions corresponding to the autocatalytic cleavage sites, the junction between the middle and the carboxyl terminal one‐third domains, and the middle domain of the open reading frame for delta antigen on the antigenomic HDV RNA were more conserved with