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Efficacy of Vaccines in Chickens against Highly Pathogenic Hong Kong H5N1 Avian Influenza

David E. Swayne, Joan R. Beck, Michael L. Perdue and Charles W. Beard
Avian Diseases
Vol. 45, No. 2 (Apr. - Jun., 2001), pp. 355-365
DOI: 10.2307/1592975
Stable URL: http://www.jstor.org/stable/1592975
Page Count: 11
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Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Efficacy of Vaccines in Chickens against Highly Pathogenic Hong Kong H5N1 Avian Influenza
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Abstract

In 1997, highly pathogenic (HP) H5N1 avian influenza virus (AIV) caused infections in poultry in Hong Kong and crossed into humans, resulting in a limited number of infections including 18 hospitalized cases and six associated deaths. The unique ability of this, AIV to infect both poultry and people raised a concern for the potential of humans to be biological as well as mechanical vectors of this AIV to poultry. The current study was undertaken to determine if existing vaccines and their technologies could be used during an outbreak to protect poultry. Commercial and experimental inactivated whole H5 AIV and baculovirus-expressed AIV H5 hemagglutinin protein vaccines provided protection from clinical signs and death in chickens after lethal challenge by human-origin HP H5N1 Hong Kong strains 156/97 and 483/97. The commercial and experimental inactivated vaccines had mean protective doses ranging from 0.25 to 0.89, which represents the milligrams of viral protein in the vaccines that provided protection from death in half of the birds. Furthermore, the vaccines reduced the ability of the challenge AIV to replicate in chickens and decreased the recovery of challenge AIV from the enteric and respiratory tracts, but the use of a vaccine will not totally prevent AI virus replication and shedding. Existing vaccines will protect poultry from mortality and reduce virus replication from the new HP AIV strain that can infect both poultry and humans. /// En 1997, el virus de influenza aviar altamente patógeno H5N1 causó infecciones en las aves domésticas en Hong Kong infectando a seres humanos, resultando en un número limitado de infecciones incluyendo 18 casos de hospitalización y seis muertes asociadas con el virus. La característica única de este virus de influenza aviar de infectar aves y personas creó la preocupación del riesgo potencial de que los humanos podían ser vectores mecánicos y biológicos de este virus de influenza aviar para las aves domésticas. El presente estudio fue realizado con el fin de determinar si las vacunas existentes y la tecnología de las mismas podían ser empleadas durante un brote para proteger las aves domésticas. Vacunas comerciales y experimentales preparadas con la proteína completa hemoaglutinina H5 y vacunas con esta misma proteína expresada en baculovirus suministraron protección contra los signos clínicos y la mortalidad en aves al ser desafiadas con las cepas altamente patógenas de origen humano H5N1 Hong Kong 156/97 y 483/97. Las vacunas comerciales y experimentales inactivadas tuvieron una dosis protectora media de 0.25 a 0.89, la cual representa los miligramos de proteína viral presente en las vacunas que suministraron una adecuada protección, evitando la muerte en la mitad de las aves. Además, las vacunas redujeron la capacidad de replicación del virus de desafío en las aves y su reaislamiento de los tractos entéricos y respiratorios. Sin embargo, el uso de la vacuna no previene en su totalidad la replicación y eliminación del virus. Las vacunas existentes protegen a las aves frente a la mortalidad ocasionada por la nueva cepa altamente patógena del virus de influenza aviar, disminuyendo su replicación.

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