Characterization of Lentogenic Newcastle Disease Virus Isolated in Jeju, Korea during 2007~2008 Surveillance

ABSTRACT

To expand the epidemiological understanding of Newcastle disease in Jeju Province, Korea, active surveillance was extensively performed through a virological examination for poultry farms and wild birds in Jeju Province during 2007~2008. Samples (swabs or fresh feces) were collected from a total of 6,485 birds including 6,405 domestic birds (chickens, ducks, pheasants, geese, quails, turkeys, and ostriches) and 80 wild birds. A total of 24 hemagglutinating agents were isolated from domestic birds on fourteen farms including five Korean native chicken, one layer chicken, two broiler chicken, four duck and two pheasant farms. The hemagglutinating agents were all identified as lentogenic NDV based on the reverse transcriptase polymerase chain reaction, sequence analysis of amino acids on the F cleavage site and mean death time in chicken embryos. The F gene-based phylogenetic analysis revealed that the NDV isolates were classified into genotypes 1 or 2 of class II. These lentogenic viruses were closely related to NDV vaccine strains used in Jeju Province. Active surveillance conducted for Newcastle disease indicates no scientific evidence of virulent NDV infection in chickens in Jeju Province, Korea since 2005.