A family of hepatotropic dna viruses which contains double-stranded DNA genomes and causes hepatitis in humans and animals. There are two genera: avihepadnavirus and orthohepadnavirus. Hepadnaviruses include hepatitis b virus, duck hepatitis B virus (hepatitis b virus, duck), heron hepatitis B virus, ground squirrel hepatitis virus, and woodchuck hepatitis B virus (hepatitis b virus, woodchuck).