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Liao CC, Tsai CH, Lo HR, Lin PR, Lin CC, Chao YC. Development of a Scrub Typhus Diagnostic Platform Incorporating Cell-Surface Display Technology. Front Immunol 2021; 12:761136. [PMID: 34707621 PMCID: PMC8542878 DOI: 10.3389/fimmu.2021.761136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Accepted: 09/23/2021] [Indexed: 11/13/2022] Open
Abstract
Scrub typhus (ST), also known as tsutsugamushi disease and caused by rickettsia Orientia tsutsugamushi, is an underestimated fatal epidemic in the Asia-Pacific region, resulting in a million human infections each year. ST is easily misdiagnosed as clinical diagnosis is based on non-specific skin eschar and flu-like symptoms. Thus, the lack of accurate, convenient, and low-cost detection methods for ST poses a global health threat. To address this problem, we adopted baculovirus surface-display technology to express three variants of TSA56, the major membrane antigen of O. tsutsugamushi, as well as the passenger domain of ScaC (ScaC-PD), on insect Sf21 cell surfaces rather than biosafety level 3 bacteria in an enzyme-linked immunosorbent assay (ELISA). Recombinant TSA56 and ScaC-PD were all properly expressed and displayed on Sf21 cells. Our cell-based ELISA comprising the four antigen-displaying cell types interacted with monoclonal antibodies as well as serum samples from ST-positive field-caught rats. This cell-based ELISA presented high accuracy (96.3%), sensitivity (98.6%), and specificity (84.6%) when tested against the ST-positive rat sera. Results of a pilot study using human sera were also highly consistent with the results of immunofluorescence analyses. By adopting this approach, we circumvented complex purification and refolding processes required to generate recombinant O. tsutsugamushi antigens and reduced the need for expensive equipment and extensively trained operators. Thus, our system has the potential to become a widely used serological platform for diagnosing ST.
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Affiliation(s)
- Chih-Chi Liao
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
| | - Chih-Hsuan Tsai
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
| | - Huei-Ru Lo
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
| | - Pey-Ru Lin
- Institute of Preventive Medicine, National Defense Medical Center, Taipei, Taiwan
| | - Chang-Chi Lin
- Institute of Preventive Medicine, National Defense Medical Center, Taipei, Taiwan
| | - Yu-Chan Chao
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan.,Department of Entomology, National Chung Hsing University, Taichung, Taiwan.,Department of Entomology, College of Bioresources and Agriculture, National Taiwan University, Taipei, Taiwan.,Department of Plant Pathology and Microbiology, College of Bioresources and Agriculture, National Taiwan University, Taipei, Taiwan
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Hsu WT, Chang CY, Tsai CH, Wei SC, Lo HR, Lamis RJS, Chang HW, Chao YC. PEDV Infection Generates Conformation-Specific Antibodies That Can Be Effectively Detected by a Cell-Based ELISA. Viruses 2021; 13:v13020303. [PMID: 33671997 PMCID: PMC7919263 DOI: 10.3390/v13020303] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Revised: 02/05/2021] [Accepted: 02/09/2021] [Indexed: 02/07/2023] Open
Abstract
Porcine epidemic diarrhea virus (PEDV) is a coronavirus that causes serious and highly contagious enteric disease in swine worldwide. In this study, we constructed a recombinant baculovirus (S-Bac) expressing full-length spike protein of the virulent epidemic genotype 2b (G2b) PEDV strain for serological studies of infected pigs. We found that most spike-specific antibodies produced upon PEDV infection in pigs are conformation-specific and they could be detected on S-Bac-infected insect cells by immunofluorescent assay, but they were insensitive to Western blot analysis, the typical method for antiserum analysis. These results indicated that spike conformation is crucial for serum recognition. Since it is difficult to purify trimeric spike membrane protein for conventional enzyme-linked immunosorbent assay (ELISA), we used S-Bac to generate a novel cell-based ELISA for convenient PEDV detection. We analyzed 100 pig serum samples, and our cell-based ELISA exhibited a sensitivity of 100%, a specificity of 97%, and almost perfect agreement [Cohen’s kappa coefficient value (κ) = 0.98] with immunocytochemical staining results. Our cell-based ELISA rapidly presented antigen for proper detection of conformation-specific antibodies, making PEDV detection more convenient, and it will be useful for detecting many viral diseases in the future.
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Affiliation(s)
- Wei-Ting Hsu
- Institute of Molecular Biology, Academia Sinica, Taipei 115, Taiwan; (W.-T.H.); (C.-H.T.); (S.-C.W.); (H.-R.L.); (R.J.S.L.)
- Graduate Institute of Life Sciences, National Defense Medical Center, Taipei 114, Taiwan
| | - Chia-Yu Chang
- School of Veterinary Medicine, National Taiwan University, Taipei 106, Taiwan; (C.-Y.C.); (H.-W.C.)
| | - Chih-Hsuan Tsai
- Institute of Molecular Biology, Academia Sinica, Taipei 115, Taiwan; (W.-T.H.); (C.-H.T.); (S.-C.W.); (H.-R.L.); (R.J.S.L.)
| | - Sung-Chan Wei
- Institute of Molecular Biology, Academia Sinica, Taipei 115, Taiwan; (W.-T.H.); (C.-H.T.); (S.-C.W.); (H.-R.L.); (R.J.S.L.)
| | - Huei-Ru Lo
- Institute of Molecular Biology, Academia Sinica, Taipei 115, Taiwan; (W.-T.H.); (C.-H.T.); (S.-C.W.); (H.-R.L.); (R.J.S.L.)
| | - Robert John S. Lamis
- Institute of Molecular Biology, Academia Sinica, Taipei 115, Taiwan; (W.-T.H.); (C.-H.T.); (S.-C.W.); (H.-R.L.); (R.J.S.L.)
- Graduate Institute of Life Sciences, National Defense Medical Center, Taipei 114, Taiwan
- Molecular and Cell Biology, Taiwan International Graduate Program, Academia Sinica and Graduate Institute of Life Science, National Defense Medical Center, Taipei 115, Taiwan
| | - Hui-Wen Chang
- School of Veterinary Medicine, National Taiwan University, Taipei 106, Taiwan; (C.-Y.C.); (H.-W.C.)
- Graduate Institute of Molecular and Comparative Pathobiology, School of Veterinary Medicine, National Taiwan University, Taipei 106, Taiwan
| | - Yu-Chan Chao
- Institute of Molecular Biology, Academia Sinica, Taipei 115, Taiwan; (W.-T.H.); (C.-H.T.); (S.-C.W.); (H.-R.L.); (R.J.S.L.)
- Graduate Institute of Life Sciences, National Defense Medical Center, Taipei 114, Taiwan
- Molecular and Cell Biology, Taiwan International Graduate Program, Academia Sinica and Graduate Institute of Life Science, National Defense Medical Center, Taipei 115, Taiwan
- Department of Entomology, National Chung Hsing University, Taichung 402, Taiwan
- Department of Plant Pathology and Microbiology, College of Bioresources and Agriculture, National Taiwan University, Taipei 106, Taiwan
- Correspondence:
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