Protective efficacy of commercial inactivated Newcastle disease virus vaccines in chickens against a recent Korean epizootic strain.
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.
Jeon
Woo-Jin
WJ
Avian Disease Division, National Veterinary Research Institute, National Veterinary Research and Quarantine Service, Anyang 430-824, Korea.
Lee
Eun-Kyoung
EK
Lee
Young-Jeong
YJ
Jeong
Ok-Mi
OM
Kim
Yong-Joo
YJ
Kwon
Jun-Hun
JH
Choi
Kang-Seuk
KS
D000281:Administration, Intranasal; D000818:Animals; D002645:Chickens; D002988:Cloaca / Q000821:virology; D004196:Disease Outbreaks / Q000517:prevention & control / Q000662:veterinary*; D007723:Korea; D009521:Newcastle Disease / Q000276:immunology* / Q000517:prevention & control; D009522:Newcastle disease virus / Q000276:immunology*; D009883:Ophthalmic Solutions; D011201:Poultry Diseases / Q000276:immunology* / Q000517:prevention & control; D015164:Vaccines, Inactivated / Q000008:administration & dosage; D014765:Viral Vaccines / Q000008:administration & dosage*; D017201:Virus Shedding / Q000187:drug effects
D009883:Ophthalmic Solutions; D015164:Vaccines, Inactivated; D014765:Viral Vaccines