Eukaryotic Expression Of NDV F And HN Gene And Immune Efficacy Of Chickens Against NDV

Newcastle disease (ND) is a severe respiratory, neurological, or enteric disease and is characterized with a high frequency of death among infected chickens. Vaccination against NDV is a common practice worldwide in the poultry industry. Due to the inherent disadvantages of conventional vaccines such as live attenuated and killed viral vaccines, there is a need to improve and extend the impact of vaccination programs against NDV. Novel strategies such as the use of DNA vaccines are being developed to produce a new generation of vaccines with improved efficacy, safe and fewer side effects. Since gene immunization was found from 1990, different gene of different virus has been delivered into different animal and good results had been obtained. DNA vaccine now becomes the focus of the vaccine field.In this study, we investigated the protection of chickens against the ND by a recombinant F and HN genes DNA vaccine. the F and HN genes of Newcastle disease virus (NDV) F48E9 strain were inserted into the eukaryotic expression vector pCAGGS, respectively. The positive recombinant plasmids were named as pCAGGS-F and pCAGGS-HN respectively after identification with restriction endonuclease analysis and sequencing analysis. Then the purified recombinant plasmids were transfected into Hela cells in vitro. The expression of NDV HN and F protein were proven by indirect immunofluorescence staining. So we got a high-expression eukaryotic vector-pCAGGS which expressed NDV F and HN proteins in vitro. The expression of F and HN gene is under the control of the human cytomegalovirus immediate early enhance and chickenβ-actin gene promoter.To test the safety of recombinant DNA vaccine, we firstly inoculated of pCAGGS-F and pCAGGS-HN into chicken embryo in China, and the result shown that the rate of hatching was 100%(6/6).To investigate immune efficacy of pCAGGS-F and pCAGGS-HN, 21-day-old SPF chickens were randomly divided into 8 groups with wing tab and inoculated intramuscularly with pCAGG-F and pCAGG-HN at different dose or combination(pCAGGS-F 100μg, pCAGGS-F 50μg, pCAGGS-HN 100 pCAGGS-HN 50μg, pCAGGS-F 50μg + pCAGGS-HN 50μg, pCAGGS-F 25μg + pCAGGS-HN 25μg,and we inoculate the second after 28 days. Four weeks after the second immunization, all chickens were challenged intramuscularly with 0.2ml 103EID50NDV F48E9 strain virus. The serum of each group were collected weekly after first inoculation, and the titer of NDV specific antibodies in serum were tested by ELISA. The result showed that the group of...