Molecular Characterization and Pathogenicity of an Indian Isolate of Duck Enteritis Virus Recovered From a Natural Outbreak

Background: Duck plague is a highly contagious viral disease reported in our country very often with significant economic loss. There are some bottlenecks with the currently used ‘Holland strain’ vaccine that involves cumbersome process of vaccine production in embryonated chicken eggs. With the future goal of development of an indigenous cell culture vaccine for duck plague, the present study is aimed at isolation of an Indian strain of DEV from a natural outbreak and its characterization for the seed virus purpose. Methods: Liver samples were collected from the suspected ducks died during a natural outbreak in Kerala and subjected to polymerase chain reaction (PCR) to confirm presence of viral DNA. The duck enteritis virus (DEV) was isolated by inoculation of PCR positive samples in embryonated duck eggs/ducklings and its pathogenicity was studied. Further, the DEV recovered from the infected duck embryo and duckling liver was confirmed by PCR amplification of the viral DNA polymerase gene and its sequence analysis. Result: Out of 12 liver samples tested eight (8) were found to be positive for duck plague by PCR. The DEV infected duck embryos and ducklings died showing typical signs and characteristic gross and microscopic lesions. PCR amplification of viral DNA targeting the DNA polymerase gene yielded amplicon of expected size of 446bp. The amplicon sequence showed 99-100% homology with other DEV isolates, thus confirming the new isolate as DEV, named as DEV/India/IVRI-2016 and the gene sequence has NCBI acc. no. KX511893.