Pathotyping of Newcastle disease viruses by RT-PCR and restriction enzyme analysis

The technique of RT-PCR and restriction enzyme analysis was standardized to detect and differentiate Newcastle disease viruses. Digestion of RT-PCR-am plified, F gene sequences encoding for the cleavage activation sites of fus ion protein with restriction enzymes AluI, BglI, HaeIII, HinfI, HhaI, RsaI, StyI and TaqI was carried out in order to characterize Newcastle disease v iruses of varying pathogenicity. Restriction enzyme digestion of the amplic ons by BglI and HhaI could group eight viruses, both field isolates and kno wn vaccine strains, into lentogenic, mesogenic and velogenic pathotypes. By employing this technique directly on a clinical sample, Newcastle disease virus of the lentogenic pathotype could be detected.