title: Comparative efficacy of North American and antigenically matched reverse genetics derived H5N9 DIVA marker vaccines against highly pathogenic Asian H5N1 avian influenza viruses in chickens.
abstract: Highly pathogenic (HP) H5N1 avian influenza has become endemic in several countries in Asia and Africa, and vaccination is being widely used as a control tool. However, there is a need for efficacious vaccines preferably utilizing a DIVA (differentiate infected from vaccinated animals) marker strategy to allow for improved surveillance of influenza in vaccinated poultry. Using a reverse genetics approach, we generated Asian rgH5N9 vaccine strain deriving the hemagglutinin gene from A/chicken/Indonesia/7/2003 (H5N1) with modification of the cleavage site to be low pathogenic (LP) and N9 neuraminidase gene from the North American LP A/turkey/Wisconsin/1968 (H5N9) virus. The recombinant rgH5N9, A/turkey/Wisconsin/1968 (H5N9) A/chicken/Hidalgo/232/1994 (H5N2), and wild type HP A/chicken/Indonesia/7/2003 (H5N1) viruses were used to prepare inactivated oil-emulsified whole virus vaccines. Two weeks after vaccination, chickens were challenged with either Asian HP H5N1 viruses, A/chicken/Indonesia/7/2003 (W.H.O. clade 2.1) or A/chicken/Supranburi Thailand/2/2004 (W.H.O. clade 1.0). The H5 HA1 of the North American vaccine strains exhibited 12% amino acid differences including amino acid changes in the major antigenic sites as compared to the Asian HP H5N1 challenge viruses, serologically exhibited substantial antigenic difference, but still provided 100% protection from mortality. However, challenge virus shedding was significantly higher in chickens immunized with antigenically distinct American lineage vaccines as compared to the antigenically matched Asian rgH5N9 and the wild type Asian H5N1 vaccine. The antibody response to the heterologous subtype neuraminidase proteins were discriminated in vaccinated and infected chickens using a rapid fluorescent 2'-(4-methylumbelliferyl)-alpha-d-N-acetylneuraminic acid sodium salt as substrate for neuraminidase inhibition assay. This study demonstrates the value of using a vaccine containing antigenically matched H5 hemagglutinin for control of HP H5N1 avian influenza in poultry and the potential utility of a heterologous neuraminidase as a DIVA marker.
authors.affiliation: Southeast Poultry Research Laboratory, Agricultural Research Service, United States Department of Agriculture, 934 College Station Road, Athens, GA 30605, USA.
authors.forename: Samadhan J
authors.initials: SJ
authors.lastname: Jadhao
authors.forename: Chang-Won
authors.initials: CW
authors.lastname: Lee
authors.forename: Matt
authors.initials: M
authors.lastname: Sylte
authors.forename: David L
authors.initials: DL
authors.lastname: Suarez
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000914:Antibodies, Viral / Q000097:blood; D000956:Antigens, Viral / Q000235:genetics / Q000276:immunology; D002645:Chickens / Q000276:immunology* / Q000821:virology; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000235:genetics / Q000276:immunology*; D053124:Influenza A Virus, H5N1 Subtype / Q000235:genetics / Q000276:immunology* / Q000472:pathogenicity; D007252:Influenza Vaccines / Q000235:genetics / Q000276:immunology*; D005585:Influenza in Birds / Q000276:immunology / Q000517:prevention & control*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009439:Neuraminidase / Q000235:genetics / Q000276:immunology; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D020539:Sequence Analysis, Protein; D022581:Vaccines, Marker / Q000235:genetics / Q000276:immunology; D017201:Virus Shedding
chemical_list: D000914:Antibodies, Viral; D000956:Antigens, Viral; D019267:Hemagglutinin Glycoproteins, Influenza Virus; D007252:Influenza Vaccines; D022581:Vaccines, Marker; C109963:hemagglutinin, avian influenza A virus; D009439:Neuraminidase