Soluble Expression of the Fiber2 Protein of Fowl Adenovirus Serotype 4 and Evaluation of the Immunogenicity of Its Subunit Vaccine
WANG Yan1,*, GAO Ya-Dong2,*, JIANG Cheng-Hui1, GE Jun-Wei2, ZENG Qiao-Ying1,**
1 College of Veterinary Medicine, Gansu Agricultural University, Lanzhou 730070, China; 2 College of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, China
Abstract：The highly pathogenic hydropericardium hepatitis syndrome (HHS) caused by fowl Adenovirus serotype 4 (FAdV-4) poses a serious threat to the poultry industry in China. There is an urgent need for an efficient vaccine for its prevention and control. As a key protective antigen of the virus, the truncated expression strategy and immune mechanism of the fiber2 protein remain unclear, which restricts the industrial application of subunit vaccines.To explore the immunological characteristics and application potential of different structural domains of the fiber2 protein of FAdV-4 and develop a safe, efficient vaccine more suitable for the poultry industry, this study analyzed and determined the regions of FAdV-4 fiber2 with good antigenicity and hydrophilicity using bioinformatics software. The full-length gene of fiber2, the gene sequences of fiber2 from 184 to 1 440 bp, and from 841 to 1 440 bp were selected to construct recombinant plasmids pET30a-FF, pET30a-FS, and pET30a-FK, respectively. Using the Escherichia coli expression system, 3 recombinant proteins of FAdV-4 fiber2, namely the full-length (FF), truncated (FS), and knob (FK) proteins, were obtained. These were prepared into subunit vaccines and inoculated into specific-pathogen-free (SPF) chickens (Gallus gallus domesticus) to evaluate their immunogenicity. The results showed that all 3 proteins were mainly expressed in a soluble form. When SPF chickens were immunized at a dose of 30 μg per bird, 100% protection was achieved after challenge. Among them, the FS protein could induce a faster and stronger specific antibody response than the inactivated whole-virus vaccine, and achieve complete protection against virus challenge at a low level of neutralizing antibodies (NAb).The minimum immunization dose test showed that when the FS recombinant protein was inoculated into chickens at a dose of 10 μg per bird, 100% protection against the virulent strain of FAdV-4 was achieved. In summary, this study innovatively established a highly efficient soluble expression system for FAdV-4 fiber2. The developed FS protein antigen had the characteristics of a rapid immune response (14 d) and low-dose protection at 10 μg per bird. This study provides basic data for further research on the immunological characteristics of the fiber2 protein and lays a theoretical foundation and technical reserve for the industrial development of new FAdV vaccines.
王艳, 高亚东, 蒋成辉, 葛俊伟, 曾巧英. 禽腺病毒4型fiber2蛋白的可溶性表达及亚单位疫苗免疫效果评价[J]. 农业生物技术学报, 2025, 33(9): 2049-2057.
WANG Yan, GAO Ya-Dong, JIANG Cheng-Hui, GE Jun-Wei, ZENG Qiao-Ying. Soluble Expression of the Fiber2 Protein of Fowl Adenovirus Serotype 4 and Evaluation of the Immunogenicity of Its Subunit Vaccine. 农业生物技术学报, 2025, 33(9): 2049-2057.
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