To study the effect of immunization of newcastle disease virus(NDV) F DNA vaccine with chicken IL-18 gene eukaryotic expression plasmid(pcDNA-chIL-18),F gene of NDV strain F48E9 was amplified by RT-PCR.The eukaryotic expression plasmid pcDNA-F(DNA vaccine) was constructed by inserting F gene into the pcDNA 3.1 vecter.11-day-old chickens were divided into 4 groups,10 chickens per group.14-day-old chickens were primarily immunized by injected intramuscularly and boosted immunized 14 days later after primary i...