Research Article

Molecular and pathological studies of duck hepatitis virus in Egypt

Ali Zanaty*, Naglaa Hagag, Mohamed Samy, Ahmed abdel-Halim, Mohamed A. Soliman, Abdel-Satar Arafa, Soad Nasif
National Laboratory for Veterinary Quality Control on poultry production NLQP, P.O. Box 264,Dokki, 12618, Giza, Egypt

Abstract

Duck Hepatitis virus (DHV) causes great economic losses in waterfowl industry worldwide. 3D gene, lies in the P3 segment of the picornavirus genome, is highly conserved and is a non-structural polyprotein gene, its encoding protein contains a conserved domain termed RNA-dependentRNA polymerase which participates in the synthesis of virus RNA during virus replication. The current work describes the surveillance of DHV in 20 commercial duck farms in Egypt with a history of high mortality in 3 to 15 day-old young ducklings from 2014 to 2016. Clinical samples were examined by Real Time-Polymerase Chain Reaction assays followed by partial sequence analysis of the 3D gene of the positive samples. Histopathological examination of the liver from selected samples was also conducted. The overall positive rate was 50% (n = 10/20). All duck breeds (Pekin, Muscovy and Mallard) used in the study were found to be susceptible to the disease. Histopathological findings of the liver samples showed pronounced lesions including hepatocyte degeneration and necrosis. Also, apoptosis were observed and bile duct hyperplasia, together with varying degrees of inflammatory cell response and haemorrhage. Sequence and phylogenetic analyses indicated that the Egyptian strains cluster in the DHAV serotype 1 with Asian viruses and distant from the vaccine strains used in Egypt.

Keywords

Duck Hepatitis virus (DHV), Histopathology, 3D gene, Sequencing, Phylogeny