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Roberts A, Dhanze H, Sharma GT, Gandhi S. Point-of-care detection of Japanese encephalitis virus biomarker in clinical samples using a portable smartphone-enabled electrochemical "Sensit" device. Bioeng Transl Med 2023; 8:e10506. [PMID: 37206199 PMCID: PMC10189466 DOI: 10.1002/btm2.10506] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Revised: 03/02/2023] [Accepted: 03/04/2023] [Indexed: 05/21/2023] Open
Abstract
Japanese encephalitis (JE), a neglected tropical zoonotic disease prevalent in south-east Asian and western pacific countries, caused by the flavivirus JE virus (JEV), has a dearth of electrochemical point-of-care (PoC) diagnostic tools available to manage endemic breakouts. To overcome this, we have developed a screen-printed carbon electrode (SPCE) immunosensor for rapid PoC detection of JEV nonstructural 1 (NS1) antigen (Ag), found circulating in serum of infected individuals using a smartphone based portable "Sensit" device. The modification of SPCE surface with JEV NS1 antibody (Ab) was confirmed via observation of globular protein structures via scanning electron microscopy (SEM), increase in electrode surface hydrophilicity via contact angle measurement and decrease in current via differential pulse voltammetry (DPV). The fabrication and testing parameters were optimized based on highest current output obtained using DPV. The SPCE was tested for detection limit of target JEV NS1 Ag ranging from 1 fM to 1 μM, which was determined as 0.45 fM in spiked serum. The disposable immunosensor was also found to be highly specific in detecting JEV NS1 Ag over other flaviviral NS1 Ag. Finally, the modified SPCE was clinically validated by testing 62 clinical JEV samples using both a portable miniaturized electrochemical "Sensit" device coupled with a smartphone and a laboratory-based potentiostat. The results were corroborated with gold-standard RT-PCR and showed 96.77% accuracy, 96.15% sensitivity, and 97.22% specificity. Hence, this technique may further be developed into a one-step rapid diagnostic tool for JEV, especially in rural areas.
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Affiliation(s)
- Akanksha Roberts
- DBT‐National Institute of Animal Biotechnology (NIAB)HyderabadTelanganaIndia
- DBT‐Regional Centre for Biotechnology (RCB)FaridabadHaryanaIndia
| | - Himani Dhanze
- ICAR‐Indian Veterinary Research Institute (IVRI)IzatnagarUttar PradeshIndia
| | - G. Taru Sharma
- DBT‐National Institute of Animal Biotechnology (NIAB)HyderabadTelanganaIndia
- DBT‐Regional Centre for Biotechnology (RCB)FaridabadHaryanaIndia
| | - Sonu Gandhi
- DBT‐National Institute of Animal Biotechnology (NIAB)HyderabadTelanganaIndia
- DBT‐Regional Centre for Biotechnology (RCB)FaridabadHaryanaIndia
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Roberts A, Prakashan D, Dhanze H, Gandham RK, Gandhi S, Sharma GT. Immuno-chromatic probe based lateral flow assay for point-of-care detection of Japanese encephalitis virus NS1 protein biomarker in clinical samples using a smartphone-based approach. NANOSCALE ADVANCES 2022; 4:3966-3977. [PMID: 36133331 PMCID: PMC9470087 DOI: 10.1039/d2na00463a] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Accepted: 08/08/2022] [Indexed: 05/08/2023]
Abstract
Lateral flow assays (LFAs) are one of the most economical, point-of-care (PoC) diagnostic assays that exploit the colorimetric properties of gold nanoparticles (AuNPs). Up to the best of our knowledge, no rapid antigen-based LFA exists for Japanese Encephalitis Virus (JEV) detection. Herein, we have reported a novel portable sandwich-type LFA for on-site detection of the non-structural 1 (NS1) secretory protein of JEV. In-house JEV NS1 antibodies (Abs) were generated and labelled with AuNPs as immunoprobes. A glass fibre membrane conjugate pad was soaked with AuNPs-Ab solution, while the JEV NS1 Ab and anti-rabbit IgG 2° Ab were coated as the test and control lines, respectively, on a nitrocellulose (NC) membrane. Different layers of the LFA were fabricated and various parameters were standardised for optimum colour intensity development. JEV negative serum samples spiked with JEV NS1 Ags (linear range - 1 pg ml-1 to 1 μg ml-1) were applied onto the sample pad and the intensity of the red colour developed on the test line increased with increasing concentration of Ag. The visual limit of detection (LOD) determined from the LFA was 10 pg ml-1, which corresponded to the LOD determined by the graphical data obtained from ImageJ software and the Colorimeter smartphone application. Furthermore, the colorimetric based immunosensor showed minimal non-specific detection of other closely related flaviviral NS1 Ags in the spiked serum, provided a rapid result within 10 min, showed storage stability up to a month at 4 °C, successfully detected the JEV NS1 protein in clinically infected pig serum samples, and hence, may be developed into a PoC screening diagnostic kit for JEV.
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Affiliation(s)
- Akanksha Roberts
- DBT-National Institute of Animal Biotechnology (NIAB) Hyderabad-500032 Telangana India +91-040-23120127
- DBT-Regional Centre for Biotechnology (RCB) Faridabad-121001 Haryana India
| | - Drishya Prakashan
- DBT-National Institute of Animal Biotechnology (NIAB) Hyderabad-500032 Telangana India +91-040-23120127
- DBT-Regional Centre for Biotechnology (RCB) Faridabad-121001 Haryana India
| | - Himani Dhanze
- ICAR-Indian Veterinary Research Institute (IVRI) Bareilly-243122 Uttar Pradesh India
| | - Ravi Kumar Gandham
- ICAR-Indian Veterinary Research Institute (IVRI) Bareilly-243122 Uttar Pradesh India
| | - Sonu Gandhi
- DBT-National Institute of Animal Biotechnology (NIAB) Hyderabad-500032 Telangana India +91-040-23120127
- DBT-Regional Centre for Biotechnology (RCB) Faridabad-121001 Haryana India
| | - G Taru Sharma
- DBT-National Institute of Animal Biotechnology (NIAB) Hyderabad-500032 Telangana India +91-040-23120127
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Roberts A, Mahari S, Gandhi S. Signal enhancing gold nanorods (GNR) and antibody modified electrochemical nanosensor for ultrasensitive detection of Japanese Encephalitis Virus (JEV) secretory Non-Structural 1 (NS1) biomarker. J Electroanal Chem (Lausanne) 2022. [DOI: 10.1016/j.jelechem.2022.116563] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
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Wan J, Wang T, Xu J, Ouyang T, Wang Q, Zhang Y, Weng S, Li Y, Wang Y, Xin X, Wang X, Li S, Kong L. Novel Japanese encephalitis virus NS1-based vaccine: Truncated NS1 fused with E. coli heat labile enterotoxin B subunit. EBioMedicine 2021; 67:103353. [PMID: 33971403 PMCID: PMC8122160 DOI: 10.1016/j.ebiom.2021.103353] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Revised: 03/06/2021] [Accepted: 04/08/2021] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Current vaccines against Japanese encephalitis virus (JEV) of flaviviruses have some disadvantages, such as the risk of virulent reversion. Non-structural protein NS1 is conserved among flaviviruses and confers immune protection without the risk of antibody-dependent enhancement (ADE). Therefore, NS1 has become a promising vaccine candidate against flaviviruses. METHODS A NS1-based vaccine (LTB-NS1∆63) with a truncated NS1 protein (NS1∆63) fused to E. coli heat-labile enterotoxin B subunit (LTB) was expressed in E.coli and explored for its ability to induce immune responses. Safety of LTB-NS1∆63 was assessed by determining its toxicity in vitro and in vivo. Protective capability of LTB-NS1∆63 and its-induced antisera was evaluated in the mice challenged with JEV by analyzing mortality and morbidity. FINDINGS LTB-NS1∆63 induced immune responses to a similar level as LTB-NS1, but more robust than NS1∆63 alone, particularly in the context of oral immunization of mice. Oral vaccination of LTB-NS1∆63 led to a higher survival rate than that of NS1∆63 or live-attenuated JEV vaccine SA14-14-2 in the mice receiving lethal JEV challenge. LTB-NS1∆63 protein also significantly decreases the morbidity of JEV-infected mice. In addition, passive transfer of LTB-NS1∆63-induced antisera provides a protection against JEV infection in mice. INTERPRETATION NS1∆63 bears JEV NS1 antigenicity. Besides, LTB-NS1∆63 could serve as a novel protein-based mucosa vaccine targeting JEV and other flaviviruses. FUNDING This work was supported by the National Natural Science Foundation, Jiangxi Province Science and Technology Committee, Education Department of Jiangxi Province.
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Affiliation(s)
- Jiawu Wan
- Institute of Pathogenic Microorganism and College of Bioscience and Engineering, Jiangxi Agricultural University, Nanchang, Jiangxi, China
| | - Ting Wang
- Institute of Pathogenic Microorganism and College of Bioscience and Engineering, Jiangxi Agricultural University, Nanchang, Jiangxi, China
| | - Jing Xu
- Institute of Pathogenic Microorganism and College of Bioscience and Engineering, Jiangxi Agricultural University, Nanchang, Jiangxi, China
| | - Tao Ouyang
- Institute of Pathogenic Microorganism and College of Bioscience and Engineering, Jiangxi Agricultural University, Nanchang, Jiangxi, China
| | - Qianruo Wang
- Institute of Pathogenic Microorganism and College of Bioscience and Engineering, Jiangxi Agricultural University, Nanchang, Jiangxi, China
| | - Yanni Zhang
- Jiangxi Province Center for Disease Control and Prevention, Nanchang, Jiangxi, China
| | - Shiqi Weng
- Institute of Pathogenic Microorganism and College of Bioscience and Engineering, Jiangxi Agricultural University, Nanchang, Jiangxi, China
| | - Yihan Li
- Institute of Pathogenic Microorganism and College of Bioscience and Engineering, Jiangxi Agricultural University, Nanchang, Jiangxi, China
| | - Yu Wang
- Institute of Pathogenic Microorganism and College of Bioscience and Engineering, Jiangxi Agricultural University, Nanchang, Jiangxi, China
| | - Xiu Xin
- Institute of Pathogenic Microorganism and College of Bioscience and Engineering, Jiangxi Agricultural University, Nanchang, Jiangxi, China
| | - Xiaoling Wang
- Institute of Pathogenic Microorganism and College of Bioscience and Engineering, Jiangxi Agricultural University, Nanchang, Jiangxi, China
| | - Sha Li
- Institute of Pathogenic Microorganism and College of Bioscience and Engineering, Jiangxi Agricultural University, Nanchang, Jiangxi, China.
| | - Lingbao Kong
- Institute of Pathogenic Microorganism and College of Bioscience and Engineering, Jiangxi Agricultural University, Nanchang, Jiangxi, China.
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Roberts A, Chauhan N, Islam S, Mahari S, Ghawri B, Gandham RK, Majumdar SS, Ghosh A, Gandhi S. Graphene functionalized field-effect transistors for ultrasensitive detection of Japanese encephalitis and Avian influenza virus. Sci Rep 2020; 10:14546. [PMID: 32884083 PMCID: PMC7471952 DOI: 10.1038/s41598-020-71591-w] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Accepted: 06/18/2020] [Indexed: 01/21/2023] Open
Abstract
Graphene, a two-dimensional nanomaterial, has gained immense interest in biosensing applications due to its large surface-to-volume ratio, and excellent electrical properties. Herein, a compact and user-friendly graphene field effect transistor (GraFET) based ultrasensitive biosensor has been developed for detecting Japanese Encephalitis Virus (JEV) and Avian Influenza Virus (AIV). The novel sensing platform comprised of carboxy functionalized graphene on Si/SiO2 substrate for covalent immobilization of monoclonal antibodies of JEV and AIV. The bioconjugation and fabrication process of GraFET was characterized by various biophysical techniques such as Ultraviolet-Visible (UV-Vis), Raman, Fourier-Transform Infrared (FT-IR) spectroscopy, optical microscopy, Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). The change in the resistance due to antigen-antibody interaction was monitored in real time to evaluate the electrical response of the sensors. The sensors were tested in the range of 1 fM to 1 μM for both JEV and AIV antigens, and showed a limit of detection (LOD) upto 1 fM and 10 fM for JEV and AIV respectively under optimised conditions. Along with ease of fabrication, the GraFET devices were highly sensitive, specific, reproducible, and capable of detecting ultralow levels of JEV and AIV antigen. Moreover, these devices can be easily integrated into miniaturized FET-based real-time sensors for the rapid, cost-effective, and early Point of Care (PoC) diagnosis of JEV and AIV.
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Affiliation(s)
- Akanksha Roberts
- DBT-National Institute of Animal Biotechnology (NIAB), Hyderabad, Telangana, 500032, India
| | - Neha Chauhan
- Department of Physics, Indian Institute of Science (IISc), Bangalore, 560012, India
| | - Saurav Islam
- Department of Physics, Indian Institute of Science (IISc), Bangalore, 560012, India
| | - Subhasis Mahari
- DBT-National Institute of Animal Biotechnology (NIAB), Hyderabad, Telangana, 500032, India
| | - Bhaskar Ghawri
- Department of Physics, Indian Institute of Science (IISc), Bangalore, 560012, India
| | - Ravi Kumar Gandham
- DBT-National Institute of Animal Biotechnology (NIAB), Hyderabad, Telangana, 500032, India
| | - S S Majumdar
- DBT-National Institute of Animal Biotechnology (NIAB), Hyderabad, Telangana, 500032, India
| | - Arindam Ghosh
- Department of Physics, Indian Institute of Science (IISc), Bangalore, 560012, India
- Center for Nanoscience and Engineering, Indian Institute of Science (IISc), Bangalore, 560012, India
| | - Sonu Gandhi
- DBT-National Institute of Animal Biotechnology (NIAB), Hyderabad, Telangana, 500032, India.
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Guevarra LA, Boado KJO, Ceñidoza FBB, Imbao MRLM, Sia MJG, Dalmacio LMM. A synthetic peptide analog of in silico-predicted immunogenic epitope unique to dengue virus serotype 2 NS1 antigen specifically binds immunoglobulin G antibodies raised in rabbits. Microbiol Immunol 2020; 64:153-161. [PMID: 31710119 DOI: 10.1111/1348-0421.12757] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Revised: 11/01/2019] [Accepted: 11/06/2019] [Indexed: 12/20/2022]
Abstract
Development of a serotyping-capable dengue detection test is hampered by the absence of an identified unique marker that can detect specific dengue virus (DENV) serotype. In the current commercially available antibody-capture diagnostic methods, immobilized nonstructural 1 (NS1) antigen indiscriminately binds and detects immunoglobulin M or immunoglobulin G against any serotype, thus limiting its capability to distinguish existing serotypes of dengue. Identification of dengue serotype is important because certain serotypes are associated with severe forms of dengue as well as dengue hemorrhagic fever. In this study, we aimed to identify an immunogenic epitope unique to DENV2 NS1 antigen and determine the binding specificity of its synthetic peptide mimotope to antibodies raised in animal models. Selection of a putative B-cell epitope from the reported DENV2 NS1 antigen was done using Kolaskar and Tongaonkar Antigenicity prediction, Emini surface accessibility prediction, and Parker hydrophilicity prediction available at the immune epitope database and analysis resource. Uniqueness of the B-cell epitope to DENV2 was analyzed by BLASTp. Immunogenicity of the synthetic peptide analog of the predicted immunogenic epitope was tested in rabbits. The binding specificity of the antibodies raised in animals and the synthetic peptide mimotope was tested by indirect ELISA. A synthetic peptide analog comprising the unique epitope of DENV2 located at the 170th-183rd position of DENV2 NS1 was found to be immunogenic in animal models. The antipeptide antibody produced in rabbits showed specific binding to the synthetic peptide mimotope of the predicted unique DENV2 NS1 immunogenic epitope.
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Affiliation(s)
- Leonardo A Guevarra
- Department of Biochemistry, Faculty of Pharmacy, University of Santo Tomas, España Blvd, Sampaloc, Manila, Philippines.,Department of Biochemistry and Molecular Biology, College of Medicine, University of the Philippines Manila, 1/F Salcedo Hall Pedro Gil St., Ermita, Manila, Philippines.,Research Center for Natural and Applied Sciences, University of Santo Tomas, España Blvd, Sampaloc, Manila, Philippines
| | - Kathleen Joyce O Boado
- Department of Biochemistry, Faculty of Pharmacy, University of Santo Tomas, España Blvd, Sampaloc, Manila, Philippines
| | - Fidel Bryan B Ceñidoza
- Department of Biochemistry, Faculty of Pharmacy, University of Santo Tomas, España Blvd, Sampaloc, Manila, Philippines
| | - Ma Rio Lauren M Imbao
- Department of Biochemistry, Faculty of Pharmacy, University of Santo Tomas, España Blvd, Sampaloc, Manila, Philippines
| | - Michelle Joy G Sia
- Department of Biochemistry, Faculty of Pharmacy, University of Santo Tomas, España Blvd, Sampaloc, Manila, Philippines
| | - Leslie Michelle M Dalmacio
- Department of Biochemistry and Molecular Biology, College of Medicine, University of the Philippines Manila, 1/F Salcedo Hall Pedro Gil St., Ermita, Manila, Philippines
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Dhanze H, Bhilegaonkar KN, Rawat S, Chethan Kumar HB, Kumar A, Gulati BR, Mishra BP, Singh RK. Development of recombinant nonstructural 1 protein based indirect enzyme linked immunosorbent assay for sero-surveillance of Japanese encephalitis in swine. J Virol Methods 2019; 272:113705. [PMID: 31351167 DOI: 10.1016/j.jviromet.2019.113705] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2019] [Revised: 07/23/2019] [Accepted: 07/23/2019] [Indexed: 11/18/2022]
Abstract
Japanese encephalitis virus (JEV) causes severe neurological disease in humans, especially among children. The disease is endemic in several South Asian countries including India. Swine play a major role as amplifier host for JEV and act as a source of infection to humans through mosquito bite. Early detection of either virus or antibodies in swine will aid to undertake control measures to prevent virus spread to humans. Swine seldom show symptoms of JEV infection and the viraemic phase lasts for a short period of 3 to 4 days indicating the potential of detection of antibodies, which remain for relatively longer period, as a suitable alternative. Cost effective and sensitive assays for the detection of JEV antibodies in swine are not available indigenously. Hence, we have developed a recombinant nonstructural protein 1 (rNS1) based enzyme linked immunosorbent assay for the detection of IgG antibodies against JEV in swine. The test is robust, highly sensitive (91%), specific (97%), reproducible and affordable. Field validation of the assay was done by screening 3628 swine Serum samples collected from different parts of India. The overall sero-positivity was found to be 32.22%. The developed ELISA can be readily incorporated into surveillance programs for detection of Japanese encephalitis virus activity in swine population thereby aiding in prediction of outbreaks in humans.
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Affiliation(s)
- H Dhanze
- ICAR- Indian Veterinary Research Institute, India.
| | | | - S Rawat
- Department of Veterinary Public Health & Epidemiology, SVPUA&T, Meerut, India
| | | | - A Kumar
- Indian Council of Agricultural Research, New Delhi, India
| | - B R Gulati
- ICAR-National Research Centre on Equines, Hisar, India
| | - B P Mishra
- ICAR- Indian Veterinary Research Institute, India
| | - R K Singh
- ICAR- Indian Veterinary Research Institute, India
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8
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Zhou D, Pei C, Yang K, Ye J, Wan S, Li Q, Zhang L, Chen H, Cao S, Song Y. Development and application of a monoclonal-antibody-based blocking ELISA for detection of Japanese encephalitis virus NS1 antibodies in swine. Arch Virol 2019; 164:1535-1542. [PMID: 30900070 DOI: 10.1007/s00705-019-04218-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Accepted: 01/18/2019] [Indexed: 11/24/2022]
Abstract
Japanese encephalitis virus (JEV) is a zoonotic pathogen transmitted by Culex mosquitoes and is the leading cause of viral encephalitis in humans. JEV infection of swine, which are the main amplifying hosts for JEV, can cause reproductive failure in sows; in boars it can cause testitis and infertility. The prevalence of JEV in swine is a continuous threat to human health. A practical diagnostic method for monitoring JEV infection in swine herds is essential for control of the disease in both swine and humans. Here, we have identified a high-affinity anti-JEV NS1 monoclonal antibody (mAb) by indirect ELISA and utilized it for the development of a blocking ELISA (bELISA). The optimal NS1 protein coating concentration (2 μg/mL) and mAb working concentration (1 μg/mL) were determined by checkerboard titration. One hundred ten JEV-antibody-negative serum samples were used to establish 34.03% inhibition as the cutoff value for a negative result. By the bELISA, seroconversion in 80% of newly JEV-vaccinated pigs was detected by 7 days post-immunization, while by the commercial envelope-protein-based iELISA, seroconversion was detected in 20% of the newly vaccinated pigs. We found 98.7% agreement between the bELISA and the commercial iELISA when we tested 157 field samples using both methods. From an epidemiological survey of swine serum collected between 2014 and 2016, we found that the average JEV seropositive rate in unvaccinated commodity pigs was 8.1%, and in vaccinated boars and sows, it was 67.6%.
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Affiliation(s)
- Dengyuan Zhou
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, 430070, Hubei, People's Republic of China.,College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, Hubei, People's Republic of China.,Key Laboratory of Veterinary Diagnostic Reagents, Ministry of Agriculture, Wuhan, 430070, Hubei, People's Republic of China
| | - Chao Pei
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, 430070, Hubei, People's Republic of China.,College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, Hubei, People's Republic of China.,Key Laboratory of Veterinary Diagnostic Reagents, Ministry of Agriculture, Wuhan, 430070, Hubei, People's Republic of China
| | - Kelu Yang
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, 430070, Hubei, People's Republic of China.,College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, Hubei, People's Republic of China.,Key Laboratory of Veterinary Diagnostic Reagents, Ministry of Agriculture, Wuhan, 430070, Hubei, People's Republic of China
| | - Jing Ye
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, 430070, Hubei, People's Republic of China.,College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, Hubei, People's Republic of China.,Key Laboratory of Veterinary Diagnostic Reagents, Ministry of Agriculture, Wuhan, 430070, Hubei, People's Republic of China
| | - Shengfeng Wan
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, 430070, Hubei, People's Republic of China.,College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, Hubei, People's Republic of China.,Key Laboratory of Veterinary Diagnostic Reagents, Ministry of Agriculture, Wuhan, 430070, Hubei, People's Republic of China
| | - Qiuyan Li
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, 430070, Hubei, People's Republic of China.,College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, Hubei, People's Republic of China.,Key Laboratory of Veterinary Diagnostic Reagents, Ministry of Agriculture, Wuhan, 430070, Hubei, People's Republic of China
| | - Luping Zhang
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, 430070, Hubei, People's Republic of China.,College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, Hubei, People's Republic of China.,Key Laboratory of Veterinary Diagnostic Reagents, Ministry of Agriculture, Wuhan, 430070, Hubei, People's Republic of China
| | - Huanchun Chen
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, 430070, Hubei, People's Republic of China.,College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, Hubei, People's Republic of China.,Key Laboratory of Veterinary Diagnostic Reagents, Ministry of Agriculture, Wuhan, 430070, Hubei, People's Republic of China
| | - Shengbo Cao
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, 430070, Hubei, People's Republic of China.,College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, Hubei, People's Republic of China.,Key Laboratory of Veterinary Diagnostic Reagents, Ministry of Agriculture, Wuhan, 430070, Hubei, People's Republic of China
| | - Yunfeng Song
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, 430070, Hubei, People's Republic of China. .,College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, Hubei, People's Republic of China. .,Key Laboratory of Veterinary Diagnostic Reagents, Ministry of Agriculture, Wuhan, 430070, Hubei, People's Republic of China.
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Host Factor SPCS1 Regulates the Replication of Japanese Encephalitis Virus through Interactions with Transmembrane Domains of NS2B. J Virol 2018; 92:JVI.00197-18. [PMID: 29593046 DOI: 10.1128/jvi.00197-18] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2018] [Accepted: 03/22/2018] [Indexed: 01/04/2023] Open
Abstract
Signal peptidase complex subunit 1 (SPCS1) is a newly identified host factor that regulates flavivirus replication, but the molecular mechanism is not fully understood. Here, using Japanese encephalitis virus (JEV) as a model, we investigated the mechanism through which the host factor SPCS1 regulates the replication of flaviviruses. We first validated the regulatory function of SPCS1 in JEV propagation by knocking down and knocking out endogenous SPCS1. The loss of SPCS1 function markedly reduced intracellular virion assembly and the production of infectious JEV particles but did not affect cell entry, RNA replication, or translation of the virus. SPCS1 was found to interact with nonstructural protein 2B (NS2B), which is involved in posttranslational protein processing and virus assembly. Serial deletion mutation of the JEV NS2B protein revealed that two transmembrane domains, NS2B(1-49) and NS2B(84-131), interact with SPCS1. Further mutagenesis analysis of conserved flavivirus residues in two SPCS1 interaction domains of NS2B demonstrated that G12A, G37A, and G47A in NS2B(1-49) and P112A in NS2B(84-131) weakened the interaction with SPCS1. Deletion mutation of SPCS1 revealed that SPCS1(91-169), which contains two transmembrane domains, was involved in interactions with both NS2B(1-49) and NS2B(84-131). Taken together, these results demonstrate that SPCS1 affects viral replication by interacting with NS2B, thereby influencing the posttranslational processing of JEV proteins and the assembly of virions.IMPORTANCE Understanding virus-host interactions is important for elucidating the molecular mechanisms of virus propagation and identifying potential antiviral targets. Previous reports demonstrated that SPCS1 is involved in the flavivirus life cycle, but the mechanism remains unknown. In this study, we confirmed that SPCS1 participates in the posttranslational protein processing and viral assembly stages of the JEV life cycle but not in the cell entry, genome RNA replication, or translation stages. Furthermore, we found that SPCS1 interacts with two independent transmembrane domains of the flavivirus NS2B protein. NS2B also interacts with NS2A, which is proposed to mediate virus assembly. Therefore, we propose a protein-protein interaction model showing how SPCS1 participates in the assembly of JEV particles. These findings expand our understanding of how host factors participate in the flavivirus replication life cycle and identify potential antiviral targets for combating flavivirus infection.
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Zhang H, Rehman MU, Li K, Luo H, Lan Y, Nabi F, Zhang L, Iqbal MK, Zhu S, Javed MT, Chamba Y, Li JK. Epidemiologic Survey of Japanese Encephalitis Virus Infection, Tibet, China, 2015. Emerg Infect Dis 2018; 23:1023-1024. [PMID: 28518046 PMCID: PMC5443422 DOI: 10.3201/eid2306.152115] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
We investigated Japanese encephalitis virus (JEV) prevalence in high-altitude regions of Tibet, China, by using standard assays to test mosquitoes, pigs, and humans. Results confirmed that JEV has spread to these areas. Disease prevention and control strategies should be used along with surveillance to limit spread of JEV in high-altitude regions of Tibet.
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Ti J, Li Z, Li X, Lu Y, Diao Y, Li F. Identification of one B-cell epitope from NS1 protein of duck Tembusu virus with monoclonal antibodies. PLoS One 2017; 12:e0181177. [PMID: 28746401 PMCID: PMC5528836 DOI: 10.1371/journal.pone.0181177] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Accepted: 06/27/2017] [Indexed: 11/29/2022] Open
Abstract
This study describes the identification of one linear B-cell epitope on TMUV NS1 protein with monoclonal antibody (mAb) 3G2 by indirect enzyme-linked immunosorbent assay (ELISA). In this study, NS1 protein was expressed in prokaryotic expression system and purified. One mAb against NS1 protein was generated from Balb/c mice immunized with recombinant protein NS1. A set of 35 partially-overlapping polypeptides covering the entire NS1 protein was expressed with PGEX-6P-1 vector and screened with mAb 3G2. One polypeptide against the mAb was acquired and identified by indirect ELISA and western-blot. To map the epitope accurately, one or two amino acid residues were removed from the carboxy and amino terminal of polypeptide sequentially. A series of truncated oligopeptides were expressed and purified. The minimal determinant of the linear B cell epitope was recognized and identified with mAb 3G2. The accurate linear B-cell epitope was 269DEKEIV274 located in NS1 protein. Furthermore, sequence alignment showed that the epitope was highly conserved and specific among TMUV strains and other flavivirus respectively. The linear B-cell epitope of TMUV NS1 protein could benefit the development of new vaccines and diagnostic assays.
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Affiliation(s)
- Jinfeng Ti
- Zoology Institute, Shan Dong Agricultural University, Shan Dong province, Tai’an, China
- Shandong Vocational Animal Science and Veterinary College, Shan Dong province, Weifang, China
| | - Zhijie Li
- Shandong Vocational Animal Science and Veterinary College, Shan Dong province, Weifang, China
| | - Xiuli Li
- Zoology Institute, Shan Dong Agricultural University, Shan Dong province, Tai’an, China
| | - Yunjian Lu
- Zoology Institute, Shan Dong Agricultural University, Shan Dong province, Tai’an, China
| | - Youxiang Diao
- Zoology Institute, Shan Dong Agricultural University, Shan Dong province, Tai’an, China
- * E-mail:
| | - Fang Li
- Shandong Vocational Animal Science and Veterinary College, Shan Dong province, Weifang, China
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Identification and characterization of a common B-cell epitope on EIAV capsid proteins. Appl Microbiol Biotechnol 2016; 100:10531-10542. [PMID: 27660181 DOI: 10.1007/s00253-016-7817-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2016] [Revised: 08/09/2016] [Accepted: 08/12/2016] [Indexed: 10/21/2022]
Abstract
The equine infectious anemia virus (EIAV) capsid protein (p26) is one of the major immunogenic proteins during EIAV infection and is widely used for the detection of EIAV antibodies in horses. However, few reports have described the use of EIAV-specific monoclonal antibodies (MAbs) in etiological and immunological detection. Previously, we developed an antigen capture enzyme-linked immunosorbent assay (AC-ELISA) for the quantification of the EIAV p26 protein level. However, the epitopes recognized by the MAbs were not identified, and the utilization of the MAbs needs to be evaluated. In this study, we characterized two monoclonal antibodies (9H8 and 1G11 MAbs) against EIAV p26. Two B-cell epitopes are located in amino acid residues, 73NLDKIAEE81 (HE) and 199KNAMRHLRPEDTLEEKMYAC218 (GE) for the 9H8 and 1G11 MAbs, respectively. The 1G11 epitope (GE) varied among viruses isolated worldwide but can be recognized by anti-EIAV sera from different regions, including China, the USA, and Argentina. Meanwhile, 1G11 MAb could react with the mutants of almost all the EIAV strains. Furthermore, we found that the histidine at position 204 (H204), leucine at position 205 (L205), and aspartic acid at position 209 (D209) of EIAV p26 individually played pivotal roles in binding with the 1G11 MAb. Our results revealed that the GE peptide might be a common B-cell binding epitope of EIAV antibodies. This is also the first report to identify a broad-spectrum monoclonal antibody (1G11) against p26 of EIAV. These findings may provide a useful basis for the development of new diagnostic assays for EIAV.
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Guo LP, Huo H, Wang XL, Bu ZG, Hua RH. Generation and characterization of a monoclonal antibody against prM protein of West Nile virus. Monoclon Antib Immunodiagn Immunother 2016; 33:438-43. [PMID: 25514166 DOI: 10.1089/mab.2014.0047] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
West Nile virus (WNV), which is an emerging pathogenic flavivirus with increasing distribution worldwide, is the cause of major human and animal health concerns. The pre-membrane (prM) protein of WNV is cleaved during maturation by the furin protease into the structural protein M and a pr-segment. In this study we generated and characterized a monoclonal antibody (MAb) against the WNV prM protein. Western blot analysis showed that the MAb reacted with WNV prM specifically. Immunohistochemistry assays demonstrated that the MAb recognized native prM protein in transfected BHK-21 cells. Preliminary studies were performed to identify the epitope recognized by the MAb using a set of synthesized overlapping peptides spanning the whole length of the prM protein. The MAb reported here may provide a valuable tool for the further exploration of the biological properties and functions of the prM protein and may also be developed for potential clinical applications.
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Affiliation(s)
- Li-Ping Guo
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences , Harbin, Heilongjiang, People's Republic of China
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Ti J, Li Z, Zhao D, Chen H, Li F, Diao Y. Development and Characterization of Monoclonal Antibodies Against NS1 Protein of Duck Tembusu Virus. Monoclon Antib Immunodiagn Immunother 2016; 35:32-6. [DOI: 10.1089/mab.2015.0061] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Jinfeng Ti
- Zoology Institute, Shandong Agricultural University, Shandong Province, China
- Shandong Vocational Animal Science and Veterinary College, Shandong Province, China
| | - Zhijie Li
- Shandong Vocational Animal Science and Veterinary College, Shandong Province, China
| | - Dandan Zhao
- Zoology Institute, Shandong Agricultural University, Shandong Province, China
| | - Hao Chen
- Zoology Institute, Shandong Agricultural University, Shandong Province, China
| | - Fang Li
- Shandong Vocational Animal Science and Veterinary College, Shandong Province, China
| | - Youxiang Diao
- Zoology Institute, Shandong Agricultural University, Shandong Province, China
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The C Terminus of the Core β-Ladder Domain in Japanese Encephalitis Virus Nonstructural Protein 1 Is Flexible for Accommodation of Heterologous Epitope Fusion. J Virol 2015; 90:1178-89. [PMID: 26559836 DOI: 10.1128/jvi.02057-15] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Accepted: 10/30/2015] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED NS1 is the only nonstructural protein that enters the lumen of the endoplasmic reticulum (ER), where NS1 is glycosylated, forms a dimer, and is subsequently secreted during flavivirus replication as dimers or hexamers, which appear to be highly immunogenic to the infected host, as protective immunity can be elicited against homologous flavivirus infections. Here, by using a trans-complementation assay, we identified the C-terminal end of NS1 derived from Japanese encephalitis virus (JEV), which was more flexible than other regions in terms of housing foreign epitopes without a significant impact on virus replication. This mapped flexible region is located in the conserved tip of the core β-ladder domain of the multimeric NS1 structure and is also known to contain certain linear epitopes, readily triggering specific antibody responses from the host. Despite becoming attenuated, recombinant JEV with insertion of a neutralizing epitope derived from enterovirus 71 (EV71) into the C-terminal end of NS1 not only could be normally released from infected cells, but also induced dual protective immunity for the host to counteract lethal challenge with either JEV or EV71 in neonatal mice. These results indicated that the secreted multimeric NS1 of flaviviruses may serve as a natural protein carrier to render epitopes of interest more immunogenic in the C terminus of the core β-ladder domain. IMPORTANCE The positive-sense RNA genomes of mosquito-borne flaviviruses appear to be flexible in terms of accommodating extra insertions of short heterologous antigens into their virus genes. Here, we illustrate that the newly identified C terminus of the core β-ladder domain in NS1 could be readily inserted into entities such as EV71 epitopes, and the resulting NS1-epitope fusion proteins appeared to maintain normal virus replication, secretion ability, and multimeric formation from infected cells. Nonetheless, such an insertion attenuated the recombinant JEV in mice, despite having retained the brain replication ability observed in wild-type JEV. Mother dams immunized with recombinant JEV expressing EV71 epitope-NS1 fused proteins elicited neutralizing antibodies that protected the newborn mice against lethal EV71 challenge. Together, our results implied a potential application of JEV NS1 as a viral carrier protein to express a heterologous epitope to stimulate dual/multiple protective immunity concurrently against several pathogens.
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Generation and efficacy evaluation of recombinant classical swine fever virus E2 glycoprotein expressed in stable transgenic mammalian cell line. PLoS One 2014; 9:e106891. [PMID: 25198669 PMCID: PMC4157854 DOI: 10.1371/journal.pone.0106891] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2014] [Accepted: 08/03/2014] [Indexed: 01/26/2023] Open
Abstract
Classical swine fever virus (CSFV) is the causative agent of classical swine fever (CSF), which is a highly contagious swine disease that causes significant economic loses to the pig industry worldwide. The envelope E2 glycoprotein of CSFV is the most important viral antigen in inducing protective immune response against CSF. In this study, we generated a mammalian cell clone (BCSFV-E2) that could stably produce a secreted form of CSFV E2 protein (mE2). The mE2 protein was shown to be N-linked glycosylated and formed a homodimer. The vaccine efficacy of mE2 was evaluated by immunizing pigs. Twenty-five 6-week-old Landrace piglets were randomly divided into five groups. Four groups were intramuscularly immunized with mE2 emulsified in different adjuvants twice at four-week intervals. One group was used as the control group. All mE2-vaccinated pigs developed CSFV-neutralizing antibodies two weeks after the first vaccination with neutralizing antibody titers ranging from 1∶40 to 1∶320. Two weeks after the booster vaccination, the neutralizing antibody titers increased greatly and ranged from 1∶10,240 to 1∶81,920. At 28 weeks after the booster vaccine was administered, the neutralizing antibody titers ranged from 1∶80 to 1∶10240. At 32 weeks after the first vaccination, pigs in all the groups were challenged with a virulent CSFV strain at a dose of 1×105 TCID50. At two weeks after the challenge, all the mE2-immunized pigs survived and exhibited no obvious symptoms of CSF. The neutralizing antibody titer at this time was 20,480. Unvaccinated pigs in the control group exhibited symptoms of CSF 3–4 days after challenge and were euthanized from 7–9 days after challenge when the pigs became moribund. These results indicate that the mE2 is a good candidate for the development of a safe and effective CSFV subunit vaccine.
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Hua RH, Li YN, Chen ZS, Liu LK, Huo H, Wang XL, Guo LP, Shen N, Wang JF, Bu ZG. Generation and characterization of a new mammalian cell line continuously expressing virus-like particles of Japanese encephalitis virus for a subunit vaccine candidate. BMC Biotechnol 2014; 14:62. [PMID: 25011456 PMCID: PMC4094896 DOI: 10.1186/1472-6750-14-62] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2014] [Accepted: 07/04/2014] [Indexed: 12/02/2022] Open
Abstract
Background Japanese encephalitis virus (JEV) is the most important cause of epidemic encephalitis in most Asian regions. There is no specific treatment available for Japanese encephalitis, and vaccination is the only effective way to prevent JEV infection in humans and domestic animals. The purpose of this study is to establish a new mammalian cell line stably and efficiently expressing virus-like particle of JEV for potential use of JEV subunit vaccine. Results We generated a new cell clone (BJ-ME cells) that stably produces a secreted form of Japanese encephalitis virus (JEV) virus-like particle (VLP). The BJ-ME cells were engineered by transfecting BHK-21 cells with a code-optimized cDNA encoding JEV prM and E protein expression plasmid. Cell line BJ-ME can stably produces a secreted form of Japanese encephalitis virus virus-like particle (JEV-VLP) which contains the JEV envelope glycoprotein (E) and membrane protein (M). The amount of JEV-VLP antigen released into the culture fluid of BJ-ME cells was as high as 15–20 μg/ml. JEV-VLP production was stable after multiple cell passages and 100% cell expression was maintained without detectable cell fusion or apoptosis. Cell culture fluid containing the JEV-VLP antigen could be harvested five to seven times continuously at intervals of 4–6 days while maintaining the culture. Mice immunized with the JEV-VLP antigen with or without adjuvant developed high titers of neutralizing antibodies and 100% protection against lethal JEV challenge. Conclusion These results suggest that the recombinant JEV-VLP antigen produced by the BJ-ME cell line is an effective, safe and affordable subunit Japanese encephalitis vaccine candidate, especially for domestic animals such as pig and horse.
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Affiliation(s)
- Rong-Hong Hua
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Maduan Street, Harbin 150001, PR China.
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Hua RH, Liu LK, Huo H, Li YN, Guo LP, Wang XL, Qin CF, Bu ZG. Comprehensive mapping of a novel NS1 epitope conserved in flaviviruses within the Japanese encephalitis virus serocomplex. Virus Res 2014; 185:103-9. [PMID: 24631788 DOI: 10.1016/j.virusres.2014.03.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2014] [Revised: 03/02/2014] [Accepted: 03/03/2014] [Indexed: 10/25/2022]
Abstract
Nonstructural protein-1 (NS1) of the Japanese encephalitis virus (JEV) is an immunogenic protein that is a potential candidate for the development of vaccines and diagnostic reagents. NS1 is known to be more specific than the E protein in serological testing of flavivirus infections. However, NS1 exhibits cross-reactivity among flaviviruses even within the same genus and more so within a serocomplex. However, the cross-reactive epitopes on JEV NS1 are poorly characterized. The present study describes the full mapping of a linear B-cell epitope that is common and specific to the JEV serocomplex of Flaviviridae. We generated an NS1-specific monoclonal antibody that cross-reacts with the West Nile virus (WNV) NS1 protein by immunizing mice with recombinant JEV NS1. For epitope mapping, 51 partially overlapping peptides spanning the entire NS1 protein were expressed with a glutathione S-transferase (GST) tag and screened using monoclonal antibodies. Two linear epitope-containing peptides were identified using enzyme-linked immunosorbent assay (ELISA). By sequentially removing amino acid residues from the carboxy and amino terminal of peptides, we successfully identified the smallest unit of the linear epitope required to react with the monoclonal antibody. The linear epitope was located in amino acids residues ²²⁷ETHTLW²³². Furthermore, results of the sequence alignment revealed that the epitope was highly conserved among JEV strains. Notably, the epitope is highly conserved among viruses of the JEV serocomplex. Furthermore, the homologous regions on NS1 proteins from dengue viruses showed no cross-reactivity with the monoclonal antibodies. The epitope was recognized by antisera against the WNV but not against the dengue virus. This novel JEV serocomplex-specific linear B-cell epitope of NS1 would be helpful in the development of new vaccines and diagnostic assays.
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Affiliation(s)
- Rong-Hong Hua
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150001, PR China.
| | - Li-Ke Liu
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150001, PR China
| | - Hong Huo
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150001, PR China
| | - Ye-Nan Li
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150001, PR China
| | - Li-Ping Guo
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150001, PR China
| | - Xiao-Lei Wang
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150001, PR China
| | - Cheng-Feng Qin
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing 100071, China
| | - Zhi-Gao Bu
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150001, PR China.
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