Objective: To characterise Newcastle disease virus isolates obtained in Victoria from 1976 to 1999 and identify the diversity of FO cleavage signal.
Design: RT-PCR using viral RNA extracted from positive NDV allantoic fluid was performed to amplify a segment of the NDV F and HN genes. Molecular characterisation of the nucleotide and amino acid sequences within the FO cleavage site was undertaken.
Results: All isolates contained 'avirulent FO cleavage signal sequence of varied amino acid composition.
Conclusions: Molecular characterisation of past and present NDV FO cleavage signal sequences will provide valuable epidemiological information and assist in understanding the genetic origins and relationships of outbreaks.