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The vaccination-challenge trial: the gold standard test to evaluate the protective efficacy of infectious coryza vaccines

Garcia, A. and Romo, F. and Ortiz, A.M. and Blackall, P.J. (2008) The vaccination-challenge trial: the gold standard test to evaluate the protective efficacy of infectious coryza vaccines. Avian Pathology, 37 (2). pp. 183-186.

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Article Link(s): http://dx.doi.org/10.1080/03079450801929941

Publisher URL: http://www.tandf.co.uk/journals/alphalist.asp

Abstract

Infectious coryza is an upper respiratory tract disease of chickens with the major impact occurring in multi-age flocks. We investigated the relationship between the level of antibodies, as detected by a haemagglutination-inhibition (HI) assay, in infectious coryza-vaccinated chickens and the protection against challenge in those chickens. In one experiment, chickens given a single dose of either of two infectious coryza vaccines lacked a detectable HI response to vaccination but showed significant levels of protection 11 weeks after vaccination. In contrast, in chickens given two doses of an infectious coryza vaccine and challenged 3 weeks after the second vaccine dose, there was a strong serological response with 36/40 birds having a HI titre of 1/20 or greater. In this trial there was an apparent relationship between titre and subsequent protection, with none of the 32 chickens with a titre of 1/40 or 1/80 showing any clinical signs and only one of the same group yielding the challenge organism on culture. In contrast, three of the four vaccinated chickens with a HI titre less than 1/5 developed the typical clinical signs of coryza and yielded the challenge organism on culture. Overall, our results suggest that HI titres cannot be regarded as a definitive predictor of vaccine efficacy. We suggest that the vaccination-challenge trial is the gold standard for the evaluation of the immune response to infectious coryza vaccines.

Item Type:Article
Corporate Creators:Animal Science
Additional Information:© Taylor & Francis.
Keywords:Infectious coryza; vaccination-challenge trial.
Subjects:Veterinary medicine > Diseases of special classes of animals > Avian
Veterinary medicine > Veterinary bacteriology
Deposited On:27 Jan 2009 06:52
Last Modified:09 Sep 2010 05:28

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