Differentiation of virulent and non-virulent Newcastle disease virus isolates using RT-PCR

Newcastle disease is one of the main concerns of poultry farmers. Detection of virulent strains of Newcastle disease virus (NDV) has a great impact on control measures against the disease. In this study RT-PCR was optimized in high sensitivity in order to differentiate the virulent from non-virulent NDV isolates directly in tissue homogenates. The vaccinal NDV strain and known field isolates were tested by this technique. RT-PCR was performed using two sets of primers chosen from a section of the F gene. The PCR product was cloned in to a pTZ57R/T vector and sequenced. The sequence data confirmed the specificity of the test. Detection of viral virulence was determined based on the amplification of PCR products. The above optimized RT-PCR produce can be used to confirm the diagnosis of Newcastle disease within 24 hrs using RNA isolated directly from tissue homogenate or passaged in SPF (Specific Pathogen Free) embryonated eggs.