Longitudinal 2 years field study of conventional vaccination against highly pathogenic avian influenza H5N1 in layer hens.
A licensed, inactivated vaccine based on a low pathogenic avian influenza virus strain (H5N2) was evaluated in layer hens kept under field conditions during a 2-year period. Vaccine efficacy was investigated by specific antibodies and by challenge-contact experiments using highly pathogenic avian influenza viruses (HPAIV) H5N1. Basic immunization with two applications induced clinical protection. Virus excretion by vaccinated hens was significantly reduced compared to non-vaccinated controls; transmission to non-vaccinated and vaccinated contact birds was not fully interrupted. Vaccination efficacy is influenced by several factors including antigenic relatedness between vaccine and field strains, but also by species, age and type of commercial uses of the host. Limitations and risks of HPAIV vaccination as silent spread of HPAIV and emergence of escape mutants must be considered a priori and appropriate corrective measures have to be installed.
Rudolf
Miriam
M
Institute of Diagnostic Virology, Friedrich-Loeffler-Institut, Südufer 10, D-17493 Greifswald-Insel Riems, Germany.
Pöppel
Manfred
M
Fröhlich
Andreas
A
Breithaupt
Angele
A
Teifke
Jens
J
Blohm
Ulrike
U
Mettenleiter
Thomas
T
Beer
Martin
M
Harder
Timm
T
D000818:Animals; D000914:Antibodies, Viral / Q000097:blood; D002460:Cell Line; D002645:Chickens / Q000276:immunology*; D004531:Eggs; D005260:Female; D006385:Hemagglutination Inhibition Tests; D053124:Influenza A Virus, H5N1 Subtype / Q000276:immunology*; D007252:Influenza Vaccines / Q000276:immunology*; D005585:Influenza in Birds / Q000276:immunology / Q000517:prevention & control* / Q000635:transmission; D007928:Lethal Dose 50; D008137:Longitudinal Studies; D012367:RNA, Viral / Q000302:isolation & purification; D015164:Vaccines, Inactivated / Q000276:immunology
D000914:Antibodies, Viral; D007252:Influenza Vaccines; D012367:RNA, Viral; D015164:Vaccines, Inactivated