ABSTRACT
Chickens were infected with chicken anemia virus (CAV) at one-day-old and vaccinated with La Sota vaccine 8 days later. Meanwhile, uninfected chickens were vaccinated as controls. At 7, 14 and 28 days post vaccination, the content of IgG,IgM,IgA and HI titer in serum, the number of T cells, IgG, IgM and IgA antibody producing cells in thymus, bursa and spleen, the proliferative response of T、B cells, the inductive activity of interleukin 2 (IL-2) and interferon (IFN) in thymus and spleen were tested. The results showed that the content of IgG, IgM, IgA and hemoagglutination inhibition (HI) titer in serum, the number of T cells, IgG, IgM and IgA antibody producing cells in thymus, bursa and spleen, the proliferative response of T cells and B cells as well as the inductive activity of IL-2 and IFN in thymus and spleen of infected-vaccinated chickens significantly decreased compared with the control. These results indicated that the immunofunction and immunoregulation were dropped post ND vaccination of CAV-infected chickens.
ABSTRACT
This study investigated the protection against the ND in chickens by a recombinant DNA vaccine. A plasmid vector encoding NDV F protein, which is reqired for virus cell fusion and is important for vaccine induced immunity, was used as a model to study how DNA vaccines may be modulated by the simulaneous expression of chicken IL-2. The NDV D26 strain F gene with CMV promotor and BGH polyA signal sequence was amplified by PCR from eukaryotic plasmid pcDNA-F, which contains the full-length NDV F gene, and clond into reconstructed eukaryotic plasmid pcDNA-IL2, which contains chicken IL-2 gene. Restriction endonuclease cleavage and PCR amplification showed that a bicistronic plasmid encoding NDV F gene and chicken IL-2 separately was successfully constructed. Two-week-old SPF chickens were intramuscularly innoculated the recombinant plasmid. Antibody and lymphocyte proliferative assay showed that the humoral and cellular immunity of chickens vaccinated the recombinant plasmid greatly increased compared with those innoculated only plasmid expressing NDV F protein. Challenged with the lethal dose of NDV F48E9 strain, 72% chickens vaccinated recombinant plasmid were survived, and 30% chickens vaccinated plasmid expressing F protein were survived. These results proved the adjuvant effect of chicken IL-2, and further showed that the efficacy of a DNA vaccine can be greatly improved by simultaneous expression of IL-2.