Phylogenetic analysis to document a common source of hepatitis D virus infection in a mother and her child

Background. Spread of hepatitis D virus (HDV) from mother to infant is rare and nucleotide evidence to document such transmission is lacking. The aim of this study was to screen the children of HDV-infected parents and compare the HDV nucleotide sequence between children and parents by phylogenetic analysis. Methods. Fifty-seven children of 28 HDV-infected parents (23 fathers and 5 mothers, including two couples) were enrolled. HDV genomes from sera of HDV-infected parents and their children were cloned and sequenced. Comparison and phylogenetic analysis of HDV genomes were based on a region from nucleotide 911 to 1260. The homology to nucleotide sequence among different genotypes was estimated by phylogenetic analysis. Results. One of the eight children whose mothers were anti-HDV positive was positive for anti-HDV. Mean heterogeneity among different HDV clones from a single subject ranged from 029% to 1.15%. HDV sequences from the mother and her child (referred from southern Taiwan) were nearly identical (99.7%), both showed 92.2-93.4% homology with other genotype II isolates from north Taiwan and 76.3-77.1% homology with genotype I isolates. Conclusions. Genotype II HDV is most prevalent in Taiwan. There are significant variations up to 8% in nucleotide sequence among different genotype II HDV clones isolated from patients in northern and southern Taiwan. Phylogenetic analysis revealed that HDV clones from the mother and her child form a monophyletic group, supporting a common source of infection. Susceptible children of HD-infected mothers should be protected by hepatitis B virus vaccination and active education.