Submitted to: Center for Investigations of Animal Production Proceedings Columbia Sa
Publication Type: Proceedings
Publication Acceptance Date: 5/6/1995
Publication Date: N/A
Citation: N/A Interpretive Summary: Field isolates of the virus that causes Newcastle disease in chickens were isolated from healthy birds in the southeastern United States and Puerto Rico. Biological properties of these viruses indicated that they were very similar to live-virus vaccines used by the poultry industry. Genetic make-up of the viruses also indicated that these viruses were derived from m live-virus vaccines. However, there was a small amount of genetic variation as compared to Newcastle disease virus vaccines. These differences were not great enough to cause disease in chickens.
Technical Abstract: Nine avirulent Newcastle disease virus isolates obtained from the southeastern United States and Puerto Rico were analyzed for pathogenicity and genetic variation. Pathotyping data indicated that these isolates were very similar to live-virus vaccines used by the poultry industry. Amino acid sequence of the fusion protein cleavage activation site further r confirmed these viruses to be avirulent vaccine-like viruses. Sequence variation at the genomic level confirmed heterogeneity among the viruses. However, this was not enough to cause any major changes in pathotype of these isolates. Based on nucleotide sequence, the isolates grouped phylogenetically with the B1 vaccine type virus.