title: Influence of maternal immunity on vaccine efficacy and susceptibility of one day old chicks against Egyptian highly pathogenic avian influenza H5N1.
abstract: In Egypt, continuous circulation of highly pathogenic avian influenza (HPAI) H5N1 viruses of clade 2.2.1 in vaccinated commercial poultry challenges strenuous control efforts. Here, vaccine-derived maternal AIV H5 specific immunity in one-day old chicks was investigated as a factor of vaccine failure in long-term blanket vaccination campaigns in broiler chickens. H5 seropositive one-day old chicks were derived from breeders repeatedly immunized with a commercial inactivated vaccine based on the Potsdam/H5N2 strain. When challenged using the antigenically related HPAIV strain Italy/98 (H5N2) clinical protection was achieved until at least 10 days post-hatch although virus replication was not fully suppressed. No protection at all was observed against the Egyptian HPAIV strain EGYvar/H5N1 representing a vaccine escape lineage. Other groups of chicks with maternal immunity were vaccinated once at 3 or 14 days of age using either the Potsdam/H5N2 vaccine or a vaccine based on EGYvar/H5N1. At day 35 of age these chicks were challenged with the Egyptian HPAIV strain EGYcls/H5N1 which co-circulates with EGYvar/H5N1 but does not represent an antigenic drift variant. The Potsdam/H5N2 vaccinated groups were not protected against EGYcls/H5N1 infection while, in contrast, the EGYvar/H5N1 vaccinated chicks withstand challenge with EGYvar/H5N1 infection. In addition, the results showed that maternal antibodies could interfere with the immune response when a homologous vaccine strain was used.
authors.affiliation: Institute of Poultry Diseases, Free University of Berlin, Koenigsweg 63-14163, Berlin, Germany.
authors.forename: E M
authors.initials: EM
authors.lastname: Abdelwhab
authors.forename: Christian
authors.initials: C
authors.lastname: Grund
authors.forename: Mona M
authors.initials: MM
authors.lastname: Aly
authors.forename: Martin
authors.initials: M
authors.lastname: Beer
authors.forename: Timm C
authors.initials: TC
authors.lastname: Harder
authors.forename: Hafez M
authors.initials: HM
authors.lastname: Hafez
mesh_terms: D000818:Animals; D000914:Antibodies, Viral / Q000097:blood; D000956:Antigens, Viral / Q000276:immunology; D002645:Chickens / Q000276:immunology / Q000821:virology; D004534:Egypt; D005260:Female; D007112:Immunity, Maternally-Acquired; D053124:Influenza A Virus, H5N1 Subtype / Q000276:immunology*; D053125:Influenza A Virus, H5N2 Subtype / Q000276:immunology; D007252:Influenza Vaccines / Q000276:immunology*; D005585:Influenza in Birds / Q000276:immunology* / Q000517:prevention & control / Q000821:virology; D008297:Male; D014611:Vaccination / Q000662:veterinary; D015164:Vaccines, Inactivated / Q000276:immunology
chemical_list: D000914:Antibodies, Viral; D000956:Antigens, Viral; D007252:Influenza Vaccines; D015164:Vaccines, Inactivated