Objective  Pathogen that caused duck liver hemorrhage in Anhui Province was identified and its genetics studied.

  Method  A suspected virus strain was isolated from the ducks suffered from liver hemorrhage at a poultry farm in Anhui Province. Pathogenic nucleic acid and an animal regression test were employed to identify the culprit. VP1 of the confirmed duck hepatitis A virus type 3 (DHAV-3) were sequenced and analyzed using biological software.

  Results  No bacterial pathogens were isolated from the culture of the diseased duck liver tissue. However, the specimens were tested positive for DHAV-3 but free of other viruses commonly known for duck liver hemorrhages by RT-PCR. The duck embryos inoculated with the isolate died with massive hemorrhages, and the 5^th generation allantoic fluid detected presence of DHAV-3 by RT-PCR. The isolate was subsequently code-named AH230225 and determined to have the effective lethal dose 50 (ELD₅₀) of 10^−4.17/0.1 mL. In an animal regression test, the Cherry Valley ducklings had a mortality rate of 80%. The dissected lesions in the liver and kidneys of the dead ducks were similar to the typical clinical specimen. The sequenced VP1 nucleotides of AH230225 showed the greatest homology of 98.8% with the DHAV-3 of Anhui isolate, AH07. Its homologies with the 10 strains of DHAV-3 listed in GenBank were 90.4%~98.8%, with DHAV-1, 62.1%–63.0%, and with DHAV-2, 64.6%–64.9%. It appeared that the VP1 of AH230225 was genetically most closely related to that of AH07 but farther from those of SD01, G, or Korean AP-04009 and AP-03337. In other words, it was distant from DHAV-1 and DHAV-2 on the evolutionary branch.

  Conclusion  The virus that caused the liver hemorrhage on ducks at the farm in Anhui was identified to be DHAV-3 with VP1 closely related genetically to that of AH07.