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Tang H, Wang R, Pang S, Han W, Zhang Q, Fang Q, Chen X, Huang Q, Qiu D, Zhou R, Li L. Native ApxIIA secreted by Actinobacillus pleuropneumoniae induces apoptosis in porcine alveolar macrophages dependent on concentration and acylation. Vet Microbiol 2023; 287:109908. [PMID: 37952264 DOI: 10.1016/j.vetmic.2023.109908] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Revised: 10/27/2023] [Accepted: 10/30/2023] [Indexed: 11/14/2023]
Abstract
Actinobacillus pleuropneumoniae is an important swine respiratory pathogen causing substantial economic losses to the global pig industry. The Apx toxins of A. pleuropneumoniae belong to the RTX toxin family and are major virulence factors. In addition to hemolysis and/or cytotoxicity via pore-forming activity, RTX toxins, such as ApxIA of A. pleuropneumoniae, have been reported to cause other effects on target cells, e.g., apoptosis. A. pleuropneumoniae ApxIIA is expressed by most serotypes and has moderate hemolytic and cytotoxic activities. In this study, porcine alveolar macrophages (3D4/21) were stimulated with different concentrations of purified native ApxIIA from the serotype 7 strain AP76 which only secretes ApxIIA. By observation of nuclear condensation via fluorescent staining and detection of apoptosis and necrosis by flow cytometry, it was found that high and low concentrations of native ApxIIA mainly caused necrosis or apoptosis of 3D4/21 cells, respectively. ApxIIA purified from an AP76 mutant with a deleted acetyltransferase gene (apxIIC) did not induce necrosis nor apoptosis. Western blot analysis using specific antibodies showed that a cleaved caspase 3 and activated capase 9 was detected after treatment of cells with a low concentration of native ApxIIA, while general or specific inhibitors of caspase 3, 8, 9 blocked these effects. ApxIIA-induced apoptosis of macrophages may be a mechanism of A. pleuropneumoniae to escape host immune clearance.
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Affiliation(s)
- Hao Tang
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei 430070, China; Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, Hubei 430070, China
| | - Rong Wang
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei 430070, China; Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, Hubei 430070, China
| | - Siqi Pang
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei 430070, China; Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, Hubei 430070, China
| | - Weiyao Han
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei 430070, China; Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, Hubei 430070, China
| | - Qiuhong Zhang
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei 430070, China; Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, Hubei 430070, China
| | - Qiong Fang
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei 430070, China; Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, Hubei 430070, China
| | - Xiabing Chen
- Institute of Animal Husbandry and Veterinary Science, Wuhan Academy of Agricultural Sciences, Wuhan, Hubei 430070, China
| | - Qi Huang
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei 430070, China; Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, Hubei 430070, China; International Research Center for Animal Disease, Ministry of Science and Technology of the People's Republic of China, Wuhan, Hubei 430070, China
| | - Dexin Qiu
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei 430070, China
| | - Rui Zhou
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei 430070, China; Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, Hubei 430070, China; International Research Center for Animal Disease, Ministry of Science and Technology of the People's Republic of China, Wuhan, Hubei 430070, China
| | - Lu Li
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei 430070, China; Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, Hubei 430070, China; International Research Center for Animal Disease, Ministry of Science and Technology of the People's Republic of China, Wuhan, Hubei 430070, China.
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To H, Nagai S, Iwata A, Koyama T, Oshima A, Tsutsumi N. Genetic and antigenic characteristics of ApxIIA and ApxIIIA from Actinobacillus pleuropneumoniae serovars 2, 3, 4, 6, 8 and 15. Microbiol Immunol 2017; 60:447-58. [PMID: 27211905 DOI: 10.1111/1348-0421.12388] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Revised: 04/21/2016] [Accepted: 05/16/2016] [Indexed: 11/30/2022]
Abstract
Apx toxins produced by Actinobacillus pleuropneumoniae are essential components of new generation vaccines. In this study, apxIIA and apxIIIA genes of serovars 2, 3, 4, 6, 8 and 15 were cloned and sequenced. Amino acid sequences of ApxIIA proteins of serovars 2, 3, 4, 6, 8 and 15 were almost identical to those of serovars 1, 5, 7, 9 and 11-13. Immunoblot analysis showed that rApxIIA from serovars 2 and 15 reacts strongly with sera from animals infected with various serovars. Sequence analysis revealed that ApxIIIA proteins has two variants, one in strains of serovar 2 and the other in strains of serovars 3, 4, 6, 8 and 15. A mouse cross-protection study showed that mice actively immunized with rApxIIIA/2 or rApxIIIA/15 are protected against challenge with A. pleuropneumoniae strains of serovars 3, 4, 6, 8, 15, and 2 expressing ApxIII/15 and ApxIII/2, respectively. Similarly, mice passively immunized with rabbit anti-rApxIIIA/2 or anti-rApxIIIA/15 sera were found to be protected against challenge with strains of serovars 2 and 15. Our study revealed antigenic and sequence similarities within ApxIIA and ApxIIIA proteins, which may help in the development of effective vaccines against disease caused by A. pleuropneumoniae.
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Affiliation(s)
- Ho To
- Nippon Institute for Biological Science, 9-2221-1 Shinmachi, Ome, Tokyo 198-0024, Japan
| | - Shinya Nagai
- Nippon Institute for Biological Science, 9-2221-1 Shinmachi, Ome, Tokyo 198-0024, Japan
| | - Akira Iwata
- Nippon Institute for Biological Science, 9-2221-1 Shinmachi, Ome, Tokyo 198-0024, Japan
| | - Tomohiro Koyama
- Nippon Institute for Biological Science, 9-2221-1 Shinmachi, Ome, Tokyo 198-0024, Japan
| | - Atsushi Oshima
- Nippon Institute for Biological Science, 9-2221-1 Shinmachi, Ome, Tokyo 198-0024, Japan
| | - Nobuyuki Tsutsumi
- Nippon Institute for Biological Science, 9-2221-1 Shinmachi, Ome, Tokyo 198-0024, Japan
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Kim MY, Kim TG, Yang MS. Production and immunogenicity of Actinobacillus pleuropneumoniae ApxIIA protein in transgenic rice callus. Protein Expr Purif 2017; 132:116-23. [PMID: 27215671 DOI: 10.1016/j.pep.2016.05.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2016] [Revised: 05/16/2016] [Accepted: 05/19/2016] [Indexed: 01/02/2023]
Abstract
Actinobacillus pleuropneumoniae is a major etiological agent that is responsible for swine pleuropneumonia, a highly contagious respiratory infection that causes severe economic losses in the swine production industry. ApxIIA is one of the virulence factors in A. pleuropneumoniae and has been considered as a candidate for developing a vaccine against the bacterial infection. A gene encoding an ApxIIA fragment (amino acids 439-801) was modified based on a plant-optimized codon and constructed into a plant expression vector under the control of a promoter and the 3' UTR of the rice amylase 3D gene. The plant expression vector was introduced into rice embryogenic callus (Oryza sativa L. cv. Dongjin) via particle bombardment-mediated transformation. The integration and transcription of the ApxIIA439-801 gene were confirmed by using genomic DNA PCR amplification and Northern blot analysis, respectively. The synthesis of ApxIIA439-801 antigen protein in transgenic rice callus was confirmed by western blot analysis. The concentration of antigen protein in lyophilized samples of transgenic rice callus was 250 μg/g. Immunizing mice with protein extracts from transgenic plants intranasally elicited secretory IgA. These results demonstrate the feasibility of using a transgenic plant to elicit immune responses against A. pleuropneumoniae.
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