Benefits and Limits of Egg Yolk vs. Serum Samples for Avian Influenza Virus Serosurveillance.
Serologic tests are a valuable tool for retrospective surveillance of avian influenza viruses (AIV) and monitoring of postvaccination host immune response. Yet collection of serum samples, particularly in adult breeder chickens, is laborious, intrusive to birds, and may pose a serious risk to the biosecurity of a flock. In this study we compared the level of AIV-specific antibody titers in eggs and serum samples obtained from broiler breeder chickens vaccinated at 6, 12, and 18 wk of age with H5N2-inactivated vaccine. Nucleocapsid protein-specific ELISA and hemagglutination inhibition test (HI) against homologous as well as heterologous antigens were used. The eggs and sera were collected at 22, 30, 45, and 50 wk of age (i.e., 4, 12, 27, and 32 wk after the third and final immunization, respectively). Using ELISA, the number of positive egg yolk samples decreased over time after vaccination, from 97% to 47%, while the seropositivity rate of serum samples was 97%-100% during the whole investigation period. No antibody titers were detected in egg white. By HI, antibody titers in serum samples were higher than in egg yolk samples. Compared to the homologous H5N2 antigen, significantly lower HI titers were obtained by using a heterologous H5N1 virus of clade 2.2.1.2. In addition, no HI titers were detected in egg yolk and/or serum samples tested against the antigen of an Egyptian H5N1 antigenic drift variant of clade 2.2.1.1. This study indicates that egg yolk may be used to monitor the postvaccination immune status of broiler breeder chickens and retrospective serosurveillance-by HI when a matching antigen is available as well as by ELISA-particularly for up to 12 wk postvaccination.
A Institute of Poultry Diseases, Free University of Berlin, Koenigsweg 63-14163 Berlin, Germany.|B National Laboratory for Veterinary Quality Control on Poultry Production (NLQP), Animal Health Research Institute, P.O. Box 246, Dokki, Giza-12618, Egypt.
E M
EM
Abdelwhab
D World Organisation for Animal Health and National Reference Laboratories for Avian Influenza and Newcastle Disease, Institute of Diagnostic Virology, Friedrich-Loeffler Institute, Suedufer 10, 17493 Isle of Riems, Greifswald, Germany.
Christian
C
Grund
B National Laboratory for Veterinary Quality Control on Poultry Production (NLQP), Animal Health Research Institute, P.O. Box 246, Dokki, Giza-12618, Egypt.
Mona M
MM
Aly
D World Organisation for Animal Health and National Reference Laboratories for Avian Influenza and Newcastle Disease, Institute of Diagnostic Virology, Friedrich-Loeffler Institute, Suedufer 10, 17493 Isle of Riems, Greifswald, Germany.
Martin
M
Beer
D World Organisation for Animal Health and National Reference Laboratories for Avian Influenza and Newcastle Disease, Institute of Diagnostic Virology, Friedrich-Loeffler Institute, Suedufer 10, 17493 Isle of Riems, Greifswald, Germany.
Timm C
TC
Harder
A Institute of Poultry Diseases, Free University of Berlin, Koenigsweg 63-14163 Berlin, Germany.
Hafez M
HM
Hafez
D000818:Animals; D001769:Blood / Q000821:virology; D002645:Chickens; D004530:Egg Yolk / Q000821:virology; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary*; D005260:Female; D006385:Hemagglutination Inhibition Tests / Q000662:veterinary*; D053125:Influenza A Virus, H5N2 Subtype / Q000302:isolation & purification*; D005585:Influenza in Birds / Q000097:blood / Q000453:epidemiology* / Q000821:virology; D011201:Poultry Diseases / Q000097:blood / Q000453:epidemiology* / Q000821:virology; D012189:Retrospective Studies
ELISA; H5N1; H5N2 vaccine; albumin; antigenic drift; avian influenza; egg yolk; hemagglutination inhibition