Evaluation of the persistence, integration, histopathology and environmental release of DNA vaccine encoding Eimeria tenella TA4 and chicken IL-2.
In a previous study, the construction of the Eimeria tenella DNA vaccine pVAX1.0-TA4-IL-2 which provides effective protection against coccidiosis was described and the immunization procedure was optimized. However, the persistence, integration, histopathology and environmental release of the DNA vaccine remain unknown. In this study, the persistence, integration and histopathology of the DNA vaccine pVAX1.0-TA4-IL-2 was evaluated in chickens in the following immunization studies: (1) single-dose immunization in one-day-old chickens; (2) repeat-dose immunization in chickens; and (3) single-high-dose immunization of three batches of plasmid in chickens. The persistence, integration, histopathology of the DNA vaccine was also evaluated in mice. At 1, 1.5, 2-4 months post immunization, blood, duodenum, heart, liver, spleen, kidneys and the immunized muscle tissue were collected from ten animals of each group. Persistence and integration were evaluated using PCR with a confirmed sensitivity of 30 plasmid copies. Hematoxylin and eosin stained sections were examined for the presence of inflammation or abnormalities that may result from vaccination. Water and fecal samples were also collected from the chicken enclosures to evaluate the potential for environmental release of the DNA vaccine. Testing various tissues by PCR confirmed that plasmid DNA persisted 1.5 months in blood, heart, liver and spleen, 2 months in kidneys and muscle of injected site. Furthermore, the vaccine did not integrate with the host genome. The histopathological examinations did not show obvious inflammation or pathological damage in any tissue of the immunized chickens. Similar results were observed in mice. Moreover, the DNA vaccine was not released into the surrounding environment. These results indicate that the DNA vaccine pVAX1.0-TA4-IL-2 has potential as safe vaccine against coccidiosis.
College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, Jiangsu 210095, PR China.
Xiaokai
X
Song
College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, Jiangsu 210095, PR China.
Zeyang
Z
Zhang
College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, Jiangsu 210095, PR China.
Chang
C
Liu
College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, Jiangsu 210095, PR China.
Lixin
L
Xu
College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, Jiangsu 210095, PR China.
Ruofeng
R
Yan
College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, Jiangsu 210095, PR China. Electronic address: lixiangrui@njau.edu.cn.
Xiangrui
X
Li
D000818:Animals; D002645:Chickens; D003048:Coccidiosis / Q000517:prevention & control / Q000662:veterinary*; D016054:DNA, Protozoan / Q000737:chemistry; D016786:Eimeria tenella / Q000235:genetics* / Q000276:immunology; D005243:Feces / Q000737:chemistry; D007376:Interleukin-2 / Q000737:chemistry / Q000235:genetics*; D051379:Mice; D010957:Plasmids; D016133:Polymerase Chain Reaction / Q000379:methods; D011201:Poultry Diseases / Q000469:parasitology / Q000517:prevention & control*; D016052:Protozoan Vaccines / Q000276:immunology*; D012680:Sensitivity and Specificity; D019444:Vaccines, DNA
D016054:DNA, Protozoan; D007376:Interleukin-2; D016052:Protozoan Vaccines; D019444:Vaccines, DNA
DNA vaccine; E. tenella; Environmental release; Histopathology; Integration; Persistence