Isolation and Pathotyping of Newcastle viruses by RT-PCR and MDT methods from broiler chickens in Fars province

Newcastle is an acute and contagious disease in poultry that has irreparable economic detriments in the poultry industry. Due to many deaths in broiler chicken flocks, it is vital to detect and characterize the viral circulation. The aim of this study was to isolation and pathotyping of Newcastle virus by RT-PCR and MDT (Mean death time) methods in broiler chickens in Fars province.

In this study 300 tracheal tissue and cloacal swab samples from 30 infected poultry farms with a high mortality and respiratory disease were collected in Fars province. The samples were inoculated in  the allantoic cavities of 9-11-day-old embryonated chicken eggs. After 72 hours incubation, the allantoic fluids were tested by hemagglutination, RT-PCR and MDT methods for the present of Newcastle virus and their pathotyping.

10 out of total samples investigated by molecular method showed a 535bp amplification band fragment and were identified as Newcastle viruses. Also, among these samples, Velogenic, Mesogenic and Lentogenic strains identified in 6, 3 and 1 sample respectively by MDT method.

Based on isolation of velogenic and mesogenic viruses in broiler chickens flocks, it is essential to continues survey vaccine strains and their effectiveness.