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Gong C, Guo M, Lou J, Zhang L, An Z, Vakharia VN, Kong W, Liu X. Identification and characterization of a highly virulent Citrobacter freundii isolate and its activation on immune responses in largemouth bass (Micropterus salmoides). FISH & SHELLFISH IMMUNOLOGY 2023; 143:109224. [PMID: 37956797 DOI: 10.1016/j.fsi.2023.109224] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Revised: 11/04/2023] [Accepted: 11/08/2023] [Indexed: 11/15/2023]
Abstract
Citrobacter freundii, a common pathogen of freshwater fish, causes significant commercial losses to the global fish farming industry. In the present study, a highly pathogenic C. freundii strain was isolated and identified from largemouth bass (Micropterus salmoides). The pathogenicity and antibiotic sensitivity of the C. freundii strain were evaluated, and the histopathology and host immune response of largemouth bass infected with C. freundii were investigated. The results showed that C. freundii was the pathogen causing disease outbreaks in largemouth bass, and the infected fish showed typical signs of acute hemorrhages and visceral enlargement. Antimicrobial susceptibility testing showed that the C. freundii strain was resistant to Kanamycin, Medimycin, Clindamycin, Penicillin, Oxacillin, Ampicillin, Cephalexin, Cefazolin, Cefradine and Vancomycin. Histopathological analysis showed different pathological changes in major tissues of diseased fish. In addition, humoral immune factors such as superoxide dismutase (SOD), catalase (CAT) and lysozyme (LZM) were used as serum indicators to evaluate the immune response of largemouth bass after infection. Quantitative real-time PCR (qRT-PCR) was performed to investigate the expression pattern of immune-related genes (CXCR1, IL-8, IRF7, IgM, CD40, IFN-γ, IL-1β, Hep1, and Hep2) in liver, spleen, and head kidney tissues, which demonstrated a strong immune response induced by C. freundii infection in largemouth bass. The present study provides insights into the pathogenic mechanism of C. freundii and immune response in largemouth bass, promoting the prevention and treatment of diseases caused by C. freundii infection.
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Affiliation(s)
- Cuiping Gong
- Huzhou Academy of Agricultural Sciences, Huzhou, 313000, China
| | - Mengya Guo
- College of Animal Science and Technology, Yangzhou University, Yangzhou, 225009, China
| | - Jianfeng Lou
- Huzhou Nanxun District Agricultural Technology Extension Service Center, Huzhou, 313000, China
| | - Liwen Zhang
- College of Animal Science and Technology, Yangzhou University, Yangzhou, 225009, China
| | - Zhenhua An
- College of Animal Science and Technology, Yangzhou University, Yangzhou, 225009, China
| | - Vikram N Vakharia
- Institute of Marine and Environmental Technology, University of Maryland Baltimore Country, Baltimore, MD, 21202, USA
| | - Weiguang Kong
- Key Laboratory of Breeding Biotechnology and Sustainable Aquaculture, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China.
| | - Xiaodan Liu
- College of Animal Science and Technology, Yangzhou University, Yangzhou, 225009, China; International Research Laboratory of Prevention and Control of Important Animal Infectious Diseases and Zoonotic Diseases of Jiangsu Higher Education Institutions, Yangzhou University, Yangzhou, China.
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Abstract
This article updates the understanding of two extirpation-driving infectious diseases, Batrachochytrium dendrobatidis and Batrachochytrium salamandrivorans, and Ranavirus. Experimental studies and dynamic, multifactorial population modeling have outlined the epidemiology and future population impacts of B dendrobatidis, B salamandrivorans, and Ranavirus. New genomic findings on divergent fungal and viral pathogens can help optimize control and disease management strategies. Although there have been major advances in knowledge of amphibian pathogens, controlled studies are needed to guide population recovery to elucidate and evaluate transmission routes for several pathogens, examine environmental control, and validate new diagnostic tools to confirm the presence of disease.
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Yu NT, Zheng XB, Liu ZX. Protective immunity induced by DNA vaccine encoding viral membrane protein against SGIV infection in grouper. FISH & SHELLFISH IMMUNOLOGY 2019; 92:649-654. [PMID: 31265911 DOI: 10.1016/j.fsi.2019.06.051] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Revised: 06/19/2019] [Accepted: 06/28/2019] [Indexed: 06/09/2023]
Abstract
Singapore grouper iridovirus (SGIV) is the main grouper-infecting virus in southern China that causes serious economic losses. However, there is no effective way to control this viral disease. In this study, SGIV ORF19R (SGIV-19R) encoding a viral membrane protein was constructed into pcDNA3.1-HA and then was used to evaluate the immune protective effects in grouper Epinephelus coioides. Subcellular localization showed that SGIV-19R distributed in the cytoplasm and co-localization analysis indicated the protein partially co-localized with the endoplasmic reticulum (ER). RT-PCR and Western blot analyses confirmed the expression of the vaccine plasmids in grouper muscle tissues. Moreover, the transcription levels of tumor necrosis factor alpha (TNF-α), interleukin-1 beta (IL-1β), myxovirus resistance 1 (Mx1) and immunoglobulin M (IgM) genes were significantly up-regulated in the spleen, liver and kidney of vaccinated groupers. SGIV challenge experiments showed the relative percent survival (RPS) was significantly enhanced in fish with 49.9% at the DNA dose of 45 μg pcDNA3.1-19R, while 75.0% RPS when using 90 μg pcDNA3.1-19R. Meanwhile, vaccination with pcDNA3.1-19R significantly reduced the virus replication, evidenced by a low viral load in the spleen of survivals groupers after SGIV challenge. These results imply that pcDNA3.1-19R could induce protective immunity in grouper, and might be a potential vaccine candidate for controlling SGIV disease.
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Affiliation(s)
- Nai-Tong Yu
- Key Laboratory of Biology and Genetic Resources of Tropical Crops, Ministry of Agriculture and Rural Affairs, Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Sciences, Haikou, 571101, China; Hainan Key Laboratory of Tropical Microbe Resources, Haikou, 571101, China.
| | - Xiao-Bao Zheng
- Key Laboratory of Biology and Genetic Resources of Tropical Crops, Ministry of Agriculture and Rural Affairs, Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Sciences, Haikou, 571101, China
| | - Zhi-Xin Liu
- Key Laboratory of Biology and Genetic Resources of Tropical Crops, Ministry of Agriculture and Rural Affairs, Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Sciences, Haikou, 571101, China
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Chen ZY, Li T, Gao XC, Wang CF, Zhang QY. Protective Immunity Induced by DNA Vaccination against Ranavirus Infection in Chinese Giant Salamander Andrias davidianus. Viruses 2018; 10:v10020052. [PMID: 29364850 PMCID: PMC5850359 DOI: 10.3390/v10020052] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Revised: 01/10/2018] [Accepted: 01/24/2018] [Indexed: 12/24/2022] Open
Abstract
Andrias davidianus ranavirus (ADRV) is an emerging viral pathogen that causes severe systemic hemorrhagic disease in Chinese giant salamanders. There is an urgent need for developing an effective vaccine against this fatal disease. In this study, DNA vaccines containing the ADRV 2L gene (pcDNA-2L) and the 58L gene (pcDNA-58L) were respectively constructed, and their immune protective effects were evaluated in Chinese giant salamanders. In vitro and in vivo expression of the vaccine plasmids were confirmed in transfected cells and muscle tissues of vaccinated Chinese giant salamanders by using immunoblot analysis or RT-PCR. Following ADRV challenge, the Chinese giant salamanders vaccinated with pcDNA-2L showed a relative percent survival (RPS) of 66.7%, which was significant higher than that in Chinese giant salamanders immunized with pcDNA-58L (RPS of 3.3%). Moreover, the specific antibody against ADRV was detected in Chinese giant salamanders vaccinated with pcDNA-2L at 14 and 21 days post-vaccination by indirect enzyme-linked immunosorbent assay (ELISA). Transcriptional analysis revealed that the expression levels of immune-related genes including type I interferon (IFN), myxovirus resistance (Mx), major histocompatibility complex class IA (MHCIA), and immunoglobulin M (IgM) were strongly up-regulated after vaccination with pcDNA-2L. Furthermore, vaccination with pcDNA-2L significantly suppressed the virus replication, which was seen by a low viral load in the spleen of Chinese giant salamander survivals after ADRV challenge. These results indicated that pcDNA-2L could induce a significant innate immune response and an adaptive immune response involving both humoral and cell-mediated immunity that conferred effective protection against ADRV infection, and might be a potential vaccine candidate for controlling ADRV disease in Chinese giant salamanders.
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Affiliation(s)
- Zhong-Yuan Chen
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China.
| | - Tao Li
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China.
| | - Xiao-Chan Gao
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China.
| | - Chen-Fei Wang
- Wang's Giant Salamander Breeding Professional Cooperative, Shiyan 442013, China.
| | - Qi-Ya Zhang
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China.
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