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Li Y, Hu Y, Tu Z, Ning Z, He Q, Fu J. Research on the Mechanism of Action of a Citrinin and Anti-Citrinin Antibody Based on Mimotope X27. Toxins (Basel) 2020; 12:toxins12100655. [PMID: 33066313 PMCID: PMC7602013 DOI: 10.3390/toxins12100655] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Revised: 10/06/2020] [Accepted: 10/08/2020] [Indexed: 12/11/2022] Open
Abstract
Immunoassays are developed based on antigen–antibody interactions. A mimotope is an effective recognition receptor used to study the mechanism of action of antigens and antibodies, and is used for improving the sensitivity of the antibody. In this study, we built a 3D structure of the citrinin (CIT) mimotope X27 and anti-CIT single-chain antibody fragment (ScFv) through a “homologous modeling” strategy. Then, CIT and X27 were respectively docked to anti-CIT ScFv by using the “molecular docking” program. Finally, T28, F29, N30, R31, and Y32 were confirmed as the key binding sites in X27. Furthermore, the result of the phage-ELISA showed that the mutational phage lost the binding activity to the anti-CIT ScFv when the five amino acids were mutated to “alanine”, thereby proving the correctness of the molecular docking model. Lastly, a site-directed saturation strategy was adopted for the sites (T28, F29, N30, R31, and Y32). Eighteen different amino acids were introduced to each site on average. The activities of all mutants were identified by indirect competitive ELISA. The sensitivities of mutants T28F, T28I, F29I, F29V, N30T, and N30V were 1.83-, 1.37-, 1.70-, 2.96-, 1.31-, and 2.01-fold higher than that of the wild-type, respectively. In conclusion, the binding model between the CIT and antibody was elaborated for the first time based on the mimotope method, thereby presenting another strategy for improving the sensitivity of citrinin detection in immunoassays.
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Affiliation(s)
- Yanping Li
- State Key Laboratory of Food Science and Technology, Jiangxi-OAI Joint Research Institute, Jiangxi Province Key Laboratory of Modern Analytical Sciences, Nanchang University, Nanchang 330047, China; (Y.L.); (Z.T.); (Q.H.)
| | - Yucheng Hu
- College of Food Science and Technology, Nanchang University, Nanchang 330047, China; (Y.H.); (Z.N.)
| | - Zhui Tu
- State Key Laboratory of Food Science and Technology, Jiangxi-OAI Joint Research Institute, Jiangxi Province Key Laboratory of Modern Analytical Sciences, Nanchang University, Nanchang 330047, China; (Y.L.); (Z.T.); (Q.H.)
| | - Zhenqiang Ning
- College of Food Science and Technology, Nanchang University, Nanchang 330047, China; (Y.H.); (Z.N.)
| | - Qinghua He
- State Key Laboratory of Food Science and Technology, Jiangxi-OAI Joint Research Institute, Jiangxi Province Key Laboratory of Modern Analytical Sciences, Nanchang University, Nanchang 330047, China; (Y.L.); (Z.T.); (Q.H.)
| | - Jinheng Fu
- State Key Laboratory of Food Science and Technology, Jiangxi-OAI Joint Research Institute, Jiangxi Province Key Laboratory of Modern Analytical Sciences, Nanchang University, Nanchang 330047, China; (Y.L.); (Z.T.); (Q.H.)
- Correspondence:
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Huang W, Tu Z, Ning Z, He Q, Li Y. Development of Real-Time Immuno-PCR Based on Phage Displayed an Anti-Idiotypic Nanobody for Quantitative Determination of Citrinin in Monascus. Toxins (Basel) 2019; 11:toxins11100572. [PMID: 31575068 PMCID: PMC6832940 DOI: 10.3390/toxins11100572] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Revised: 09/18/2019] [Accepted: 09/26/2019] [Indexed: 01/01/2023] Open
Abstract
Citrinin (CIT) is a mycotoxin that has been detected in agricultural products, feedstuff, and Monascus products. At present, research has been performed to develop methods for CIT detection, mainly through TLC, HPLC, biosensor, and immunoassay. The immunoassay method is popular with researchers because of its speed, economy, simplicity, and ease of control. However, mycotoxins are inevitably introduced during the determination. Immunoassays require the use of toxins coupled to carrier proteins or enzymes to make competitive antigens. In this study, anti-idiotypic nanobody X27 as CIT mimetic antigen was used as non-toxic surrogate reagents in immunoassay. Therefore, the X27-based real-time immuno-PCR (rtIPCR) method had been established after optimal experiments of annealing temperature and amplification efficiency of real-time PCR, concentration of coating antibody, phage X27, and methyl alcohol. The IC50 value of the established method in the present study is 9.86 ± 2.52 ng/mL, which is nearly equivalent to the traditional phage ELISA method. However, the linear range is of 0.1-1000 ng/mL, which has been broadened 10-fold compared to the phage ELISA method. Besides, the X27-based rtIPCR method has no cross-reactivity to the common mycotoxins, like aflatoxin B1 (AFB1), deoxynivalenol (DON), ochratoxin A (OTA), and zearalenone (ZEN). The method has also been applied to the determination of CIT in rice flour and flour samples, and the recovery was found to be in the range of 90.0-104.6% and 75.8-110.0% respectively. There was no significant difference in the results between the rtIPCR and UPLC-MS. The anti-idiotypic nanobody as a non-toxic surrogate of CIT makes rtIPCR a promising method for actual CIT analysis in Monascus products.
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Affiliation(s)
- Wenping Huang
- State Key Laboratory of Food Science and Technology, Jiangxi-OAI Joint Research Institute, Jiangxi Province Key Laboratory of Modern Analytical Sciences, Nanchang University, Nanchang 330047, China.
| | - Zhui Tu
- State Key Laboratory of Food Science and Technology, Jiangxi-OAI Joint Research Institute, Jiangxi Province Key Laboratory of Modern Analytical Sciences, Nanchang University, Nanchang 330047, China.
| | - Zhenqiang Ning
- State Key Laboratory of Food Science and Technology, Jiangxi-OAI Joint Research Institute, Jiangxi Province Key Laboratory of Modern Analytical Sciences, Nanchang University, Nanchang 330047, China.
| | - Qinghua He
- State Key Laboratory of Food Science and Technology, Jiangxi-OAI Joint Research Institute, Jiangxi Province Key Laboratory of Modern Analytical Sciences, Nanchang University, Nanchang 330047, China.
| | - Yanping Li
- State Key Laboratory of Food Science and Technology, Jiangxi-OAI Joint Research Institute, Jiangxi Province Key Laboratory of Modern Analytical Sciences, Nanchang University, Nanchang 330047, China.
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Cheng H, Yang Y, Chen Y, Chen X, Cai Z, Du A. Novel monoclonal antibody-based immunochromatographic strip for detecting citrinin in fruit from Zhejiang province, China. PLoS One 2018; 13:e0197179. [PMID: 29742170 PMCID: PMC5942799 DOI: 10.1371/journal.pone.0197179] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Accepted: 04/27/2018] [Indexed: 11/18/2022] Open
Abstract
Citrinin (CIT) is a hepato-nephrotoxic fungal metabolite produced by the genera Penicillium, Aspergillus and Monascu. There is an increasing demand for rapid and economical methods for detection CIT residues in fruit. In this study, we developed an immunochromatographic strip (ICS) for detection of citrinin (CIT) residues in fruit for the first time. Anti-CIT monoclonal antibody (McAb) 2B9 was prepared, with a binding affinity of 9.39 × 108 L/moL. Conjugates CIT-BSA and McAb 2B9 were used to develop the ICS which could be completed in 5 min, with the detection limit of 50 ng/mL and no cross reactivity with other mycotoxins. Analysis of CIT in 64 fruit samples revealed that data obtained from the ICS test were in good agreement with indirect competitive enzyme-linked immunosorbent assays (ic-ELISAs) and high performance liquid chromatography (HPLC). This result demonstrated that the ICS test could be used as a rapid, reliable, cost-effective and user-friendly qualitative tool for detection of CIT residues on-site.
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Affiliation(s)
- Haiwei Cheng
- Institute of Preventive Veterinary Medicine & Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, College of Animal Sciences, Zhejiang University, Hangzhou, China
- National Research Center of Engineering and Technology for Veterinary Biologicals, Ministry of Agriculture, Key Laboratory of Veterinary Biological Engineering and Technology, Jiangsu Academy of Agricultural Sciences, Nanjing, China
- Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, China
| | - Yi Yang
- Institute of Preventive Veterinary Medicine & Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, College of Animal Sciences, Zhejiang University, Hangzhou, China
| | - Yifei Chen
- Institute of Preventive Veterinary Medicine & Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, College of Animal Sciences, Zhejiang University, Hangzhou, China
| | - Xueqiu Chen
- Institute of Preventive Veterinary Medicine & Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, College of Animal Sciences, Zhejiang University, Hangzhou, China
| | - Zizheng Cai
- Nanjing Agricultural University, Nanjing, China
| | - Aifang Du
- Institute of Preventive Veterinary Medicine & Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, College of Animal Sciences, Zhejiang University, Hangzhou, China
- * E-mail:
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Liu R, Yu Z, He Q, Xu Y. [Preparation and identification of a monoclonal antibody against citrinin]. Wei Sheng Yan Jiu 2007; 36:190-3. [PMID: 17555098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
OBJECTIVE To prepare the monoclonal antibody (McAb) against citrinin. METHODS Four citrinin-protein conjugates (A, B, C and D) were synthesized by the active ester, Munnich Reaction and 1,1-carbonyldiimidazole (CDI) method, respectively. BALB/c mice were immunized with the conjugates for producing the McAb against citrinin. RESULTS The antibodies against citrinin have been produced in serum of immunized BALB/c mice with the conjugate C. A McAb against citrinin was acquired according to the traditional procedure. Cross reactivity of the McAb was less than 0.01% with ochratoxin A, patulin, aflatoxin B1, deoxynivalenol and zearalenone, respectively. A competitive enzyme-linked immunosorbent assay was developed. The linear range of ELISA was between 20 ng/ml and 1 000 ng/ml, the detectable limit was 10 ng/ml. Recovery of citrinin from wheat spiked with citrinin was from 95% to 112%, the coefficient of variation was 12.2% to 20.4%. CONCLUSION The McAb against citrinin was acquired successfully.
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Affiliation(s)
- Renrong Liu
- The Key Laboratory of Food Science of MOE, Nanchang University, Nanchang 330047, China
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Johannessen LN, Nilsen AM, Løvik M. The mycotoxins citrinin and gliotoxin differentially affect production of the pro-inflammatory cytokines tumour necrosis factor-alpha and interleukin-6, and the anti-inflammatory cytokine interleukin-10. Clin Exp Allergy 2006; 35:782-9. [PMID: 15969670 DOI: 10.1111/j.1365-2222.2005.02249.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
BACKGROUND Microbial growth is considered one of the major causes of indoor air problems. Moulds have been associated with asthma, allergy and a wide range of diffuse indoor air-related symptoms. However, mechanisms of the adverse health effects are not well understood. OBJECTIVE We hypothesized that the mycotoxins citrinin and gliotoxin could cause an imbalance between the secretion of the pro-inflammatory cytokines TNF-alpha and IL-6 and the anti-inflammatory cytokine IL-10. METHODS We investigated the influence of citrinin and gliotoxin on the human monocytic cell line Mono-Mac-6 (MM6) with and without lipopolysaccharide -stimulation. The levels of IL-10, IL-6 and TNF-alpha were analysed in cell culture supernatants by ELISA. Cell viability and cell apoptosis were measured by flow cytometry. RESULTS The strongest inhibition of cytokine secretion was found for IL-10. IL-6 levels were found to decrease in a dose-dependent manner along with reduced cell viability. TNF-alpha levels increased with low gliotoxin exposure (less than 100 ng/mL), but decreased significantly at 375 ng/mL and higher along with increased cell apoptosis and reduced cell viability. TNF-alpha levels were not reduced by citrinin exposure. CONCLUSION We observed a cytokine imbalance with a more pronounced reduction of IL-10 concentrations compared with those of TNF-alpha and IL-6. We suggest that low exposure doses of citrinin and gliotoxin (corresponding to less than 100 ng/mL gliotoxin and less than 10 mug/mL citrinin) may inhibit IL-10 and lead to increased risk of an inflammatory response with relative overproduction of TNF-alpha and IL-6. The findings and their clinical implications must be verified by human studies. However, we speculate that the observed biological effects may be of importance as they may partly explain the occurrence of diffuse general indoor air-related symptoms as well as the worsening of asthmatic inflammatory reactions experienced in mouldy environments.
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Affiliation(s)
- L N Johannessen
- Department of Cancer Research and Molecular Medicine, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim, Norway.
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Affiliation(s)
- D Abramson
- Cereal Research Centre, Agriculture and Agri-Food Canada, Winnipeg, Canada
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Abstract
An indirect competitive enzyme immunoassay using rabbit antisera could detect citrinin in buffer solutions at 1 to 13 ng/ml (0.05 to 0.65 ng per assay). Cross-reactivity with austdiol, alternariol, ochratoxin A, and deoxynivalenol was < 0.1% relative to citrinin. Recovery of citrinin added to wheat flour at 200 to 2,000 ng/g was 89 to 104%, with a coefficient of variation of 6.9 to 13%.
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Affiliation(s)
- D Abramson
- Agriculture and Agri-Food Canada, Winnipeg Research Center, Manitoba
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