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Use of a modified bacterial ghost lysis system for the construction of an inactivated avian pathogenic Escherichia coli vaccine candidate
- Hu, Jiangang, Zuo, Jiakun, Chen, Zhaoguo, Fu, Lixia, Lv, Xiaolong, Hu, Shijun, Shi, Xingchi, Jing, Yawei, Wang, Yalei, Wang, Zhihao, Mi, Rongsheng, Huang, Yan, Liu, Dahai, Qi, Kezong, Han, Xiangan
- Veterinary microbiology 2019 v.229 pp. 48-58
- Escherichia coli, Gram-negative bacteria, antibodies, chickens, cross immunity, enzyme-linked immunosorbent assay, genes, interferon-gamma, micrococcal nuclease, pericarditis, plasmids, serotypes, tumor necrosis factor-alpha, vaccination, vaccines, virulence
- Vaccination is an effective strategy to prevent avian colibacillosis. Bacterial ghosts (BGs) are prepared by the controlled expression of the phiX174 gene E, which mediates the lysis of Gram-negative bacteria. Staphylococcal nuclease A may be used to produce BGs for further inactivation of host bacteria and elimination of residual genetic material. In this study, the double promoter lysis plasmid (pUC19-ΔcI857-E-rrnB-pL-SN) was successfully constructed and BGs were prepared at 37 °C. The cleavage efficiency of Escherichia coli BGs was 99.9%. Furthermore, to evaluate the immunological effects of the BG vaccines in chickens, a BG vaccine was prepared using the serotype O2 avian pathogenic Escherichia coli deletion strain (DE17ΔluxSΔaroA). The results showed that the BG vaccine was able to achieve over 90% immune protection against virulent challenge using the same serotype O2 strain (DE17 or CE35), while it showed poor cross-protection against serotypes O1 and O78 (data not shown). The enzyme-linked immunosorbent assay results showed that the antibody levels in the immunized groups were higher than in the control group (p < 0.05), with the BG group being the highest. The cytokine tests showed that the levels of interferon-γ in the BG immune group were higher than in the phosphate-buffered saline (PBS) control group (non-immune) (p < 0.01) and the formalin-inactivated vaccine immune group (p < 0.05), and the levels of tumor necrosis factor-α in the BG group were higher than in the formalin-inactivated vaccine (p > 0.05) and the PBS control groups (p < 0.05). In addition, pathological analysis revealed that the PBS control group showed typical fibrinous pericarditis and perihepatitis, whereas the immune group showed no obvious pathological changes. In summary, our findings provide a new strategy for the prevention and control of avian colibacillosis.