tetano
Editor, Senior Moderator
Res Vet Sci. 2014 Sep 19. pii: S0034-5288(14)00250-1. doi: 10.1016/j.rvsc.2014.09.013. [Epub ahead of print]
Silent spread of highly pathogenic Avian Influenza H5N1 virus amongst vaccinated commercial layers.
Poetri ON1, Van Boven M2, Claassen I3, Koch G3, Wibawan IW4, Stegeman A5, Van den Broek J5, Bouma A5.
Author information
Abstract
The aim of this study was to determine whether a single vaccination of commercial layer type chickens with an inactivated vaccine containing highly pathogenic avian influenza virus strain H5N1 A/chicken/Legok/2003, carried out on the farm, was sufficient to protect against infection with the homologous virus strain. A transmission experiment was carried out with pairs of chicken of which one was inoculated with H5N1 virus and the other contact-exposed. Results showed that the majority of the vaccinated birds developed haemagglutination inhibition (HI) titres below 4log2. No clinical signs were observed in the vaccinated birds and virus shedding was limited. However, nearly all vaccinated birds showed a four-fold or higher increase of HI titres after challenge or contact-exposure, which is an indication of infection. This implies that virus transmission most likely has occurred. This study showed that a single vaccination applied under field conditions induced clinical protection, but was insufficient to induce protection against virus transmission, suggesting that silent spread of virus in vaccinated commercial flocks may occur.
Copyright ? 2014 Elsevier Ltd. All rights reserved.
KEYWORDS:
Avian influenza; H5N1; Layer; Transmission; Vaccination
PMID:
25301756
[PubMed - as supplied by publisher]
http://www.ncbi.nlm.nih.gov/pubmed/25301756
Silent spread of highly pathogenic Avian Influenza H5N1 virus amongst vaccinated commercial layers.
Poetri ON1, Van Boven M2, Claassen I3, Koch G3, Wibawan IW4, Stegeman A5, Van den Broek J5, Bouma A5.
Author information
Abstract
The aim of this study was to determine whether a single vaccination of commercial layer type chickens with an inactivated vaccine containing highly pathogenic avian influenza virus strain H5N1 A/chicken/Legok/2003, carried out on the farm, was sufficient to protect against infection with the homologous virus strain. A transmission experiment was carried out with pairs of chicken of which one was inoculated with H5N1 virus and the other contact-exposed. Results showed that the majority of the vaccinated birds developed haemagglutination inhibition (HI) titres below 4log2. No clinical signs were observed in the vaccinated birds and virus shedding was limited. However, nearly all vaccinated birds showed a four-fold or higher increase of HI titres after challenge or contact-exposure, which is an indication of infection. This implies that virus transmission most likely has occurred. This study showed that a single vaccination applied under field conditions induced clinical protection, but was insufficient to induce protection against virus transmission, suggesting that silent spread of virus in vaccinated commercial flocks may occur.
Copyright ? 2014 Elsevier Ltd. All rights reserved.
KEYWORDS:
Avian influenza; H5N1; Layer; Transmission; Vaccination
PMID:
25301756
[PubMed - as supplied by publisher]
http://www.ncbi.nlm.nih.gov/pubmed/25301756