Protection of chickens against infectious bronchitis virus with a multivalent DNA vaccine and boosting with an inactivated vaccine

Yan, Fang; Zhao, Yujun; Hu, Yongting; Qiu, Jianyang; Lei, Wenxin; Ji, Wenhui; Li, Xuying; Wu, Qian; Shi, Xiumin; Li, Zhong

Our animal research in our study had been approved by Shanxi Province Animal Disease Control Center (China). The plasmids used were amplified in Escherichia (E.) coli DH5α cells (TaKaRa, Japan), and extracted using a PureYield Plasmid Maxiprep System (Promega, USA). Seven-day-old chickens were randomly divided into seven groups of 20 chickens each and immunized intramuscularly on 7, 21, and 35 day-old, using different vaccination strategies (Table 1 ). Each group of chickens was injected with 100 μg (1 μg/μL) monovalent DNA vaccine (pVAX1-16S1, pVAX1-16M, and pVAX1-16N) respectively and 0.5 mL inactivated IBV vaccine. pVAX1-16S1/M/N was a multivalent DNA vaccine containing 100 μg of each plasmid (equivalent molar ratios for each DNA component) and therefore delivered the same dose of each expression plasmid targeting the S1, N, or M, respectively, as each monovalent vaccine. All the chickens were immunized intramuscularly with the vaccines. Peripheral blood samples were also collected from five randomly selected chickens from each group from the jugular vein into heparinized capillary tubes (Laiwu Yaohua Pharmaceutical Packing, China) when the birds were 7, 21, 35, and 49 days old.