HomePhilippine Journal of Veterinary Medicinevol. 54 no. 1 (2017)

Molecular Characterization and Phylogenetic Analysis of Newcastle Disease Virus Isolated from Clinical Cases of Newcastle Disease in Commercial Layer Farms in the Philippines

Dennis V. Umali, Dvm, Phd | Anna Luisa M. Lopez | Maria Immaculada P. Torres | Mel C. Umandal | Hiromitsu Katoh

 

Abstract:

Newcastle Disease (ND) is an economically devastating disease of poultry. At present, limited data are available regarding the molecular characteristics of Newcastle disease virus (NDV) from the Philippines. Clinical and molecular characterizations were performed on five clinical cases of ND in vaccinated commercial layer farms from four provinces in the Philippines, namely Bulacan, Pampanga, Zamboanga del Sur and Davao Del Sur. Clinical signs observed on affected flocks were conjunctivitis, gasping, tracheal rales, facial swelling, lethargy, greenish diarrhea, torticollis and paralysis. Disease onset ranged from 21 to 124 days with mortality rates of 15 to 61%. Gross morphological lesions identified were

Presence of serous exudates in the infraorbital sinuses, hemorrhagic trachea, inflamed spleen, liver and kidneys and petechial hemorrhages in the proventriculus and cecal tonsils. Nucleotide sequencing showed that all feld strains were velogenic with F0 proteolytic cleavage site of 112RRRKR*F117 and 112RRQKR*F117 patterns. Phylogenetic analysis showed that all feld NDV strains belong to class II genotype VII, subgenotypes VIIa, VIIh and VIIi. Evolutionary divergence showed that the feld NDV strains were closely related (up to 99% similarity) to the newly identified subgenotypes of virulent NDVs currently emerging in Southeast Asia and the Middle East.