Study Of A Recombinant Newcastle Disease Virus (NDV) Expressing The Hemagglutinin Protein Of H9 Subtype Avian Influenza Virus (AIV)

Office International des Epizooties (OIE) regulates infectious diseases of A category, including two birds of potent infectious diseases, were highly pathogenic avian influenza(AI)and Newcastle disease(ND). Vaccination to prevent the two epidemics are the most effective measure, but Attenuated and inactivated vaccine immunization would interfere with existing technology under the conditions of the immune surveillance and epidemiological investigation,increaseing the difficulty for ND and AI diagnosis and clearance group;Genetic engineering subunit vaccine although showing a good immune response, but high production costs, the short duration of immunity, it is impossible to become the ideal vaccine to prevent epidemics. The DNA vaccine research has just started, There are many issues to be resolved about the newly emerging Nucleic Acid Vaccines.. In recent years, with the development of recombinant DNA technology and reverse genetics technology, it is enabled for the development of vaccines to overcome the traditional shortcomings of the genetically engineered vaccine .Now the live vector vaccine of NDV is researching more,the protection of this genetically engineered vaccine is more efficient, without interferenceing with the clinical testing and quarantine.It is very promising for a class of genetically engineered vaccines.In this study we rescued a recombinant New castle virus(NDV) rL-H9 HA which expressed a wild type H9 subtype Avian influenza virus(AIV) hemagglutinin gene by used reverse genetics of Lasota vaccine strain. The recombinant virus rL-H9 HA was confirmed by inderect immunofluorescence assay,RT-PCR and sequencing, Western-blot.The MDT of the recombinant virus is≥168h, furthermore both ICPI and IVPI is 0. The recombinant viruses maintained similar high growing titers in embryo and low pathogenicity as the parent srain did. After the rL-H9 HA viruses passaged in embryonated SPF chiken eggs for 9 passages, no mutions in HA gene were found and the biological characterization of the recombinant viruses are unchanged. To evaluate the vaccine efficacy of rL-H9 HA viruse, SPF chickens were inoculated with 106 EID50 of the recombinant virus, and 21 days after inoculation, the chichens were challenged with chiken lethal dose of F48E9 or H9 subtype AIV 002 . The result show that rL-H9HA vaccine protected chickens 100% against F48E9 NDV. For H9 virus, 1/10 of the oropharyngeal and cloacal swabs of the chickens were positive for virus detection at 3 days after challenged with 002 virus. However, only one chiken shed virus at 5 days and the virus titers were much lower than the control group. The results indicate that recombinant rL-H9HA virus can be used as a bivalent vaccine and have potential use in preventing H9 subtype AI and ND.