MOLECULAR AND PATHOLOGICAL EVIDENCE OF DUCK VIRAL ENTERITIS: FIRST CONFIRMED REPORT IN MANILA DUCK (CAIRINA MOSCHATA) IN SOUTHERN INDIA

Abstract

This study reports the foremost incidence of duck viral enteritis (DVE) outbreak in a freerange flock of 250 Manila ducks from Tamil Nadu, Southern India. A sudden 20% (n=50) mortality was observed in the duck flock, presenting clinical signs such as greenish or blood-stained diarrhea, anorexia, ocular discharge, incoordination, and death. Postmortem examination of randomly selected 10 carcasses revealed blood in the body cavities, hemorrhages in the heart, air sacs, proventriculus, liver, and spleen, and enlargement of kidney, spleen, and liver with necrotic foci. Histopathological examination evidenced congestion and hemorrhages in the proventriculus, heart, and air sacs. The liver exhibited diffused congestion and hepatic steatosis. Spleen evinced congestion, hemorrhages, and multifocal necrotic areas. The small intestine showed blunting and fusion of villi with mononuclear cell infiltration. Screening of pooled viscera demonstrated no specific bacterial etiology and was negative for NDV and DHAV genomes. PCR screening for the DVEV genome targeting partial UL-31 showed amplification of 446bp amplicon in all the 10 carcasses examined. Sequencing and alignment of PCR amplicon from one sample yielded 373 nucleotides encoding 94 amino acids and gene sequence submitted to the GenBank with accession number of OR725707. BLAST homology search showed 100% sequence identity with published Anatid alphaherpesvirus 1 genomes available in GenBank. Phylogenetic analysis revealed specific grouping along with published DVEV genomes of India, Bangladesh, China, USA, and Germany. Further, deduced amino acid comparison with established DVEV amino acid sequences also showed a 100% match to the published DVEV sequences.

Keywords

• duck viral enteritis
• manila duck
• gross pathology
• histopathology
• molecular diagnosis