Abstract
This study was conducted to characterize avian encephalomyelitis (AE) viruses obtained from various flocks of breeder and commercial chickens in South Korea. Young chicken less than 4 weeks old showed neurological sign were diagnosed as typical AE infection between 2006 and 2011. In 2013, idiopathic AE occurred on the unvaccinated 79 day-old chickens that had clinical signs of ataxia and paralysis. Phylogenetic analysis of viral protein 2 genes of AE viruses showed that all AE field viruses tested were genetically similar to vaccine strain [Calnek 1143]. In the embryo-inoculation test via the yolk sac, only one field strain and one commercial vaccine were embryo-adapted. The results indicated that the AE outbreaks in South Korea were caused by strains genetically similar to vaccine strain indicating possibility of vaccine breakdown or persistence in the chicken population.
