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A 6.5-kb specific fragment containing the T7 promoter and the transcription vector was excised from the full-length eDNA clone of the Newcastle disease virus (NDV) strain ZJI of goose origin,and thereafter it was self-ligated to form a high quality plasmid for mutagenesis.Site-directed mutagenesis was used for inserting three additional G nucleotides (nts) into the region between the T7 promoter and the leader sequence of the NDV genome.RT-PCR was employed to amplify the F/HN gene fragments,and then they were ligated by the shared restriction enzyme BsmBI.Finally,the corresponding fragment in the mutant full-length eDNA was substituted with the new one.The sequencing results showed that the three additional Gnts were successfully inserted and the mutant nts in the full-length eDNA were corrected.This study lays a good foundation for research on the reverse genetics of NDV strain ZJI.