Advances in research on genetic relationships of waterfowl parvoviruses

Derzsy’s disease and Muscovy duck parvovirus disease have become common diseases in waterfowl culture in the world and their potential to cause harm has risen. The causative agents are goose parvovirus (GPV) and Muscovy duck parvovirus (MDPV), which can provoke similar clinical symptoms and high mortality and morbidity rates. In recent years, duck short beak and dwarfism syndrome has been prevalent in the Cherry Valley duck population in eastern China. It is characterised by the physical signs for which it is named. Although the mortality rate is low, it causes stunting and weight loss, which have caused serious economic losses to the waterfowl industry. The virus that causes this disease was named novel goose parvovirus (NGPV). This article summarises the latest research on the genetic relationships of the three parvoviruses, and reviews the aetiology, epidemiology, and necropsy characteristics in infected ducks, in order to facilitate further study.

Pathodynamics of Circulating Strains of Duck Enteritis Virus: A Step Forward to Understand Its Pathogenesis

Duck enteritis virus (DEV) causes an acute and contagious infection in duck. The present study was carried out to evaluate the pathogenicity and pathodynamics of DEV isolates from different natural outbreaks in the Assam Province of India. A total of six wild-type isolates of DEV were revived in ducklings to determine its biologic characterization. Postmortem examination of infected ducklings revealed DEV-specific gross lesions in different organs. The presence of DEV was confirmed by its genome amplification and the presence of viral antigens from collected tissue samples by indirect fluorescent antibody test. All the isolates revived in ducklings were further propagated in duck embryo fibroblast cells. Highly virulent and low virulent isolates of DEV were selected for further study based on median duck infectivity dose (DID₅₀) and median tissue culture infectivity dose (TCID₅₀). The highly virulent isolate of DEV had values of 10² DID₅₀/ml and 10^6.33 TCID₅₀/ml, whereas the low virulent strain had titers of 10 DID₅₀/ml and 10^4.83 TCID₅₀/ml in the cell culture. Our results showed replication of DEV in ducks with the highest and lowest viral titers in the thymus and bursa of Fabricius, respectively. In addition, microscopic analysis revealed necrosis and degeneration of submucosal esophageal glands and glandular epithelium. The study will be useful to understand the organ tropism and pathologic alteration among the virulent DEV isolates.