his family consists of double-stranded DNA viruses with an icosahedral nucleocapsid. They have been recovered from many mammalian and avian species. Many are found in the respiratory tract and infections are often persistent. Only a small number cause significant veterinary diseases. | his family consists of double-stranded DNA viruses with an icosahedral nucleocapsid. They have been recovered from many mammalian and avian species. Many are found in the respiratory tract and infections are often persistent. Only a small number cause significant veterinary diseases. |