title: H9N2 avian influenza virus-induced conjunctivitis model for vaccine efficacy testing.
abstract: Clinical signs such as respiratory signs, egg drop, and mortality have been reported in field cases of low pathogenic avian influenza by H9N2 avian influenza virus (AIV) but have rarely been reproduced by the virus alone. Thus, virus reisolation rates and titers in tissues were measured for vaccine efficacy testing. In the present study, we established a clinical sign-based vaccine efficacy test by reproduction of highly frequent conjunctivitis (77.8%-90%) via binocular instillation of an H9N2 virus (01310) strain, 1 x 10(6) EID50/10 microl for each eye). Specific-pathogen-free chickens were assigned to vaccine and control groups, and the vaccine group was inoculated intramuscularly with a commercial H9N2 inactivated oil emulsion vaccine. The chickens were challenged by 01310 via binocular instillation at 2 and 4 wk postvaccination (WPV). The positive rates of conjunctivitis and virus reisolation were significantly different between the vaccine and control groups (conjunctivitis at 2 WPV, 0% vs. 77.8%, and at 4 WPV, 0% vs. 80%). Vaccine antibody was detected in tears as well as in serum samples of the vaccine group before challenge. The conjunctivitis model may be useful for efficacy testing of AI vaccine due to a clinical symptom-based read of results, but further efficacy testings with different types, doses of AI vaccines, and challenge viruses will be required to complete the evaluation of our model.
authors.affiliation: Laboratory of Avian Diseases, College of Veterinary Medicine and BK21 for Veterinary Science, Seoul National University, Gwanakro 599, Daehak-Dong, Gwanak-Gu, Seoul 151-742, Republic of Korea.
authors.forename: Il-Hwan
authors.initials: IH
authors.lastname: Kim
authors.forename: Hyuk-Joon
authors.initials: HJ
authors.lastname: Kwon
authors.forename: Jae-Hong
authors.initials: JH
authors.lastname: Kimabce
mesh_terms: D000818:Animals; D002642:Chick Embryo; D002645:Chickens; D003236:Conjunctivitis, Viral / Q000276:immunology / Q000517:prevention & control / Q000662:veterinary* / Q000821:virology; D004306:Dose-Response Relationship, Immunologic; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary; D053127:Influenza A Virus, H9N2 Subtype / Q000276:immunology*; D007252:Influenza Vaccines / Q000276:immunology*; D005585:Influenza in Birds / Q000150:complications / Q000276:immunology / Q000517:prevention & control*; D007273:Injections, Intramuscular / Q000662:veterinary; D011201:Poultry Diseases / Q000276:immunology / Q000517:prevention & control* / Q000821:virology; D013047:Specific Pathogen-Free Organisms; D015164:Vaccines, Inactivated / Q000276:immunology
chemical_list: D007252:Influenza Vaccines; D015164:Vaccines, Inactivated