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J Vet Sci. 2008 Sep;9(3):295-300 |
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Protective efficacy of commercial inactivated Newcastle disease virus vaccines in chickens against a recent Korean epizootic strain
Woo-Jin Jeon, Eun-Kyoung Lee, Young-Jeong Lee, Ok-Mi Jeong, Yong-Joo Kim, Jun-Hun Kwon, Kang-Seuk Choi* |
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Avian Disease Division, National Veterinary Research Institute, National Veterinary Research and Quarantine Service, Anyang 430-824, Korea
* choiks@nvrqs.go.kr |
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Despite the intensive vaccination policy that has been put in
place to control Newcastle disease virus (NDV), the recent
emergence of NDV genotype VII strains in Korea has led to
significant economic losses in the poultry industry. We
assessed the ability of inactivated, oil-emulsion vaccines
derived from La Sota or Ulster 2C NDV strains to protect
chickens from challenge with Kr-005/00, which is a recently
isolated Korean epizootic genotype VII strain. Six-week-old
SPF chickens were vaccinated once and challenged three
weeks later via the eye drop/intranasal route. All vaccinated
birds were fully protected from disease, regardless of the
vaccine strains used. All vaccinated and challenged groups
showed significant sero-conversion 14 days after challenge.
However, some vaccinated birds, despite being protected
from disease, shed the challenge virus from their oro-pharynx
and cloaca, albeit at significantly lower titers than the
unvaccinated challenged control birds. The virological,
serological, and epidemiological significance of our
observations with regard to NDV disease eradication is
discussed.
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