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The resistance of meat chickens vaccinated by aerosol with a live V4 Newcastle disease virus vaccine in the field to challenge with a velogenic Newcastle disease virus
Author(s) -
BELL IG,
NICHOLLS PJ,
NORMAN C.,
IDERIS AINI,
CROSS GM
Publication year - 1991
Publication title -
australian veterinary journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.382
H-Index - 59
eISSN - 1751-0813
pISSN - 0005-0423
DOI - 10.1111/j.1751-0813.1991.tb00763.x
Subject(s) - newcastle disease , vaccination , virology , virus , outbreak , immunity , attenuated vaccine , antibody , biology , broiler , virulence , immunology , immune system , zoology , biochemistry , gene
SUMMARY Meat chickens housed on a commercial broiler farm in Australia were vaccinated once at 10 to 11 days‐of‐age by aerosol with live V4 Newcastle disease virus (NDV) vaccine. Groups of vaccinated and unvaccinated birds were flown to Malaysia, where they were challenged with a virulent strain of NDV. Survival rates in vaccinated chickens challenged 7, 14, 21 or 31 d after vaccination were 0.47, 0.77, 0.97 and 0.92, respectively. All unvaccinated chickens died due to Newcastle disease (ND) following challenge. Chickens in Australia and Malaysia were bled and the serums tested for haemagglutination‐inhibiting (HI) antibody to NDV. Many vaccinated birds with no detectable antibody, and all birds with a log 2 titre of 2 or greater, survived challenge. The results showed that this V4 vaccine induced protective immunity in a significant proportion of chickens within 7 d of mass aerosol vaccination. This early immunity occurred in the absence of detectable circulating HI antibody. Non‐HI antibody mediated immunity continued to provide protection up to 31 d after vaccination. Almost all vaccinated birds were protected within 3 w of vaccination. It is concluded that the V4 vaccine is efficacious and could be useful during an outbreak of virulent ND in Australia.