ISOLATION, CHARACTERIZATION OF NEWCASTLE DISEASE VIRUS AND COMPARITIVE EFFICACY OF DIFFERENT VACCINE REGIMES IN BROILER BIRDS
F. Afzal, U. Saliha, N. Fawad, S. Ahmed, Habib-ur-Rehman, J. Munawar, G. Naheed and B. Siddique
Directorate of Poultry Research Institute, Murree Road, Rawalpindi, Pakistan
Corresponding author e-mail: firstname.lastname@example.org
Newcastle disease is a highly contagious disease of poultry and is cause of huge economic losses during 2011-2012 in Pakistan. Regardless of vaccination the disease has caused considerable mortalities in all types of poultry. In this study samples were taken from suspected flocks showing signs and symptoms of the disease. Isolation was done by chicken embryo inoculation and identification of the virus was done by Haemagglutination (HA) and Haemagglutination Inhibition (HI) assay. Presence of the virus was confirmed by Reverse Transcriptase-Polymerase Chain Reaction (RT-PCR). All of the four virus isolates were found velogenic when pathotyped on the basis of Mean Death Time (MDT) and Intra Cerebral Pathogenicity Index (ICPI). Killed Vaccine was prepared from Chicken/Broiler /Attock /2012 having maximum pathogenicity. Evaluation of the vaccine was done in randomly divided seven groups of broilers each having 42birds.One group was kept as control. These groups were vaccinated with different vaccines and different vaccine schedules. There was non-significant difference in HI log 2 titers of different groups. Vaccinated group in which priming with lentogenic strain, followed by vaccination with experimentally produced killed vaccine having local velogenic NDV strain and followed by boosting with lentogenic strain showed maximum protection (92.85%) against the challenge of local velogenic NDV isolate.
Key words: Newcastle disease, Pathotype, Phylogenetic tree, Vaccine.