Document Type: Original Articles
Department of Poultry and obstetrics, Science and Research Branch, Islamic Azad University, Tehran, Iran
Department of Clinical Science, Faculty of Veterinary Medicine, Karaj Branch, Islamic Azad University, Alborz, Iran
Department of Microbiology and Immunology, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran
Newcastle disease is a highly contagious viral infection affecting many species of birds which can spread fast between poultry houses and cause heavy economic burden on the poultry industry all around world. Fusion and hemagglutinin-neuraminidase (HN) protein are important in pathogenesis of newcastle disease virus. HN protein is critical viral protein with multiple functions plays a key role to form the NDV’s virulence. The head of HN protein is responsible for receptor binding, neuraminidase activity. The aim of this study was to investigate the sequence homology of hemagglutinin-neuraminidase of two Newcastle disease virus isolates sampled over the infected farms in Iran. Samples were collected from flocks that had been vaccinated by both types of live and killed vaccines for NDV. After isolation NDV, the viruses were subjected to the polymerase chain reaction (PCR) amplifications using two pairs of specific primers designed for HN gene to amplify complete HN gene (1730bp). Next, the PCR products were sequenced and analyzed by phylogenetic tree constructing software. The analysis showed substantial sequence homology among Iranian isolates which is ranged between 97.1 to 100%. Moreover, the sequence homology searching revealed a level of similarity between HN sequences of Iranian isolates and the HN sequences from other countries particularly those in Asia. For instance, we found high homology ratio (95.34%) between Iranian isolates and the sequences registered on online molecular databases from China. Based on phylogenetic analysis the NDV isolates belong to the VIId genotype. Monitoring of circulation NDVs from poultry and other birds would help to obtain an insight into the evolution of NDVs and control of panzootic viruses in future.