title: Decreased neutralizing antigenicity in IBV S1 protein expressed from mammalian cells.
abstract: We evaluated the antigenicity of recombinant infectious bronchitis virus (IBV) S1 protein expressed in mammalian cells. Recombinant S1 was expressed as a secreted protein fused with a trimerization motif peptide, then purified using Ni Sepharose. The purified protein was analyzed by Western blotting, mixed with oil adjuvant, and administered to 29-day-old specific-pathogen-free chickens. Six weeks after immunization, anti-IBV neutralizing titer and anti-S1 ELISA titer were determined; immunized chickens then were inoculated with IBV via the trachea and ciliary activity was observed. Results showed that the recombinant S1 protein was highly glycosylated, and the neutralizing antigenicity of recombinant S1 protein was lower than that of inactivated virus. However, anti-S1 ELISA indicated that the recombinant S1 protein induced antibodies against S1. These results suggest that the recombinant S1 may retain non-neutralizing epitopes but have unnatural glycosylation pattern and conformation, resulting in lacking neutralizing conformational epitopes. In conclusion, the neutralizing antigenicity of recombinant S1 protein expressed from mammalian cells was decreased, and was not sufficient to induce neutralizing antibodies.
authors.affiliation: Animal Pharmaceuticals Division, The Chemo-Sero-Therapeutic Research Institute, 1-6-1 Okubo, Kita-ku, Kumamoto-shi, Kumamoto 860-8568, Japan. Electronic address: andou-ki@kaketsuken.or.jp.
authors.forename: Kiyohiko
authors.initials: K
authors.lastname: Andoh
authors.affiliation: R&D Division, The Chemo-Sero-Therapeutic Research Institute, Kikuchi Research Center, 1314-1 Kyokushikawabe, Kikuchi-shi, Kumamoto 869-1298, Japan.
authors.forename: Kiyotaka
authors.initials: K
authors.lastname: Suenaga
authors.affiliation: R&D Division, The Chemo-Sero-Therapeutic Research Institute, Kikuchi Research Center, 1314-1 Kyokushikawabe, Kikuchi-shi, Kumamoto 869-1298, Japan.
authors.forename: Masashi
authors.initials: M
authors.lastname: Sakaguchi
authors.affiliation: Animal Pharmaceuticals Division, The Chemo-Sero-Therapeutic Research Institute, 1-6-1 Okubo, Kita-ku, Kumamoto-shi, Kumamoto 860-8568, Japan.
authors.forename: Kenichi
authors.initials: K
authors.lastname: Yamazaki
authors.affiliation: Animal Pharmaceuticals Division, The Chemo-Sero-Therapeutic Research Institute, 1-6-1 Okubo, Kita-ku, Kumamoto-shi, Kumamoto 860-8568, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Honda
mesh_terms: D000818:Animals; D057134:Antibodies, Neutralizing / Q000276:immunology; D000914:Antibodies, Viral / Q000276:immunology; D002645:Chickens; D018352:Coronavirus Infections / Q000276:immunology / Q000662:veterinary* / Q000821:virology; D007114:Immunization; D001351:Infectious bronchitis virus / Q000235:genetics / Q000276:immunology*; D011201:Poultry Diseases / Q000276:immunology / Q000821:virology*; D011994:Recombinant Proteins / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology; D013047:Specific Pathogen-Free Organisms; D064370:Spike Glycoprotein, Coronavirus / Q000235:genetics / Q000276:immunology*; D014765:Viral Vaccines / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology
chemical_list: D057134:Antibodies, Neutralizing; D000914:Antibodies, Viral; D011994:Recombinant Proteins; D064370:Spike Glycoprotein, Coronavirus; D014765:Viral Vaccines
keywords: Conformational epitope; Infectious bronchitis virus; Neutralizing antibody; S1; Spike protein