title: Expression of HA of HPAI H5N1 virus at US2 gene insertion site of turkey herpesvirus induced better protection than that at US10 gene insertion site.
abstract: Herpesvirus of turkey (HVT) is being widely used as a vector for development of recombinant vaccines and US2 and US10 genes are often chosen as insertion sites for targeted gene expression. However, the different effects of the two genes for generation of recombinant HVT vaccines were unknown. In order to compare the effects of inserted genes in the two sites on the efficacy of the recombinant vaccines, host-protective haemagglutinin (HA) gene of the highly pathogenic avian influenza virus (HPAIV) H5N1 was inserted into either US2 or US10 gene locus of the HVT. The resulting US2 (rHVT-US2-HA) or US10 (rHVT-US10-HA) recombinant HVT viruses were used to infect chicken embryo fibroblasts. Plaques and the growth kinetics of rHVT-US2-HA-infected chicken embryo fibroblasts were similar to those of parental HVT whereas rHVT-US10-HA infected chicken embryo fibroblasts had different growth kinetics and plaque formation. The viremia levels in rHVT-US10-HA virus-infected chickens were significantly lower than those of rHVT-US2-HA group on 28 days post infection. The vaccine efficacy of the two recombinant viruses against H5N1 HPAIV and virulent Marek's disease virus was also evaluated in 1-day-old vaccinated chickens. rHVT-US2-HA-vaccinated chickens were better protected with reduced mortality than rHVT-US10-HA-vaccinated animals following HPAIV challenge. Furthermore, the overall hemaglutination inhibition antibody titers of rHVT-US2-HA-vaccinated chickens were higher than those of rHVT-US10-HA-vaccinated chickens. Protection levels against Marek's disease virus challenge following vaccination with either rHVT-US2-HA or rHVT-US10-HA, however, were similar to those of the parental HVT virus. These results, for the first time, indicate that US2 gene provides a favorable foreign gene insertion site for generation of recombinant HVT vaccines.
authors.affiliation: Division of Avian Infectious Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, The Chinese Academy of Agricultural Sciences, Harbin, China.
authors.forename: Hongbo
authors.initials: H
authors.lastname: Gao
authors.forename: Hongyu
authors.initials: H
authors.lastname: Cui
authors.forename: Xianlan
authors.initials: X
authors.lastname: Cui
authors.forename: Xingming
authors.initials: X
authors.lastname: Shi
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhao
authors.forename: Xiaoyan
authors.initials: X
authors.lastname: Zhao
authors.forename: Yanming
authors.initials: Y
authors.lastname: Quan
authors.forename: Shuai
authors.initials: S
authors.lastname: Yan
authors.forename: Weiwei
authors.initials: W
authors.lastname: Zeng
authors.forename: Yunfeng
authors.initials: Y
authors.lastname: Wang
mesh_terms: D000818:Animals; D015139:Blotting, Southern; D015153:Blotting, Western; D002642:Chick Embryo; D002645:Chickens / Q000821:virology; D005455:Fluorescent Antibody Technique; D005814:Genes, Viral / Q000235:genetics*; D006386:Hemagglutination Tests; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000378:metabolism*; D026002:Herpesvirus 1, Meleagrid / Q000235:genetics*; D008381:Herpesvirus 2, Gallid / Q000276:immunology; D053124:Influenza A Virus, H5N1 Subtype / Q000276:immunology*; D007252:Influenza Vaccines / Q000276:immunology; D005585:Influenza in Birds / Q000276:immunology* / Q000517:prevention & control* / Q000821:virology; D016254:Mutagenesis, Insertional / Q000235:genetics*; D011995:Recombination, Genetic / Q000235:genetics; D016896:Treatment Outcome; D014766:Viremia / Q000276:immunology / Q000821:virology
chemical_list: D019267:Hemagglutinin Glycoproteins, Influenza Virus; D007252:Influenza Vaccines