Identification and Sequence Analysis of Duck Hepatitis A Virus Type 1 Isolated from Muscovy Duckling with Pancreatitis

Samples came from Muscovy ducklings with yellowed or hemorrhagic pancreatitis were positive for duck hepatitis A virus-1 (DHAV-1) by RT-PCR.A virus strain (named as MPZJ1206) was abtained from Virus-containing allantoic fluid after inoculation of embryonated Muscovy duck eggs with DHAV-1-positive samples. The isolate shows no hemagglutinating activity with chickens, ducks or sheep red blood cells at different temperature.Plaque purified virus was specifically neutralized by anti-DHAV-1 hyperimmune serum.Seven-day-old Muscovy ducklings inoculated with the virus showed a mortality rate of 38.5%, and yielded the same pathological characteristics as those of clinical onset duck had.The virus strain also recovered from the pancreas of Muscovy duckling died in the trials.A 714-bp fregment gene was abtained by using a set of primers aimed at VP1 ORF gene, and shared 99.1% nucleotide sequence identity with that of classical DHAV-1 strain Du/CH/LGD/111239. Phylogenetic analysis showed that MPZJ1206 strain lay in the viral lineage of DHAV-1.The above results indicate that pancreatitis in Muscovy ducklings was caused due to the infection of duck hepatitis A virus type 1, and this pathotype is distincted from hemorrhagic hepatitis caused by classical duck hepatitis A virus, so it advised that the virus isolated in this study could be named as pancreatitis-type DHAV-1.