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@#Objective To develop and verify a double antibody sandwich ELISA method for quantitative detection of TrypLE.Methods The optimal concentration of capture antibody and detection antibody were determined by orthogonal experiments to develop TrypLE double antibody sandwich ELISA quantitative detection method,which was verified for linear range,specificity,limit of detection(LOD),limit of quantitation(LOQ),accuracy and reproducibility.A variety of biological products were detected by the developed method to verify the applicability.Results The TrypLE double antibody sandwich ELISA quantitative detection method was established by using 3 μg/mL capture antibody and 15 000 times dilution of detection antibody,with a linear range of 0.41 ～ 40.00 ng/mL,a LOD of 0.258 ng/mL,a LOQ of 0.5 ng/mL.The measurement deviation was less than 5% and the CV of reproducibility verification was less than 5% when detecting standards and samples.The recovery rates of different types of samples were within 80% ～ 120%.Conclusion The established TrypLE double antibody sandwich ELISA quantitative detection method accurately,effectively and quickly detected residual amount of TrypLE in various types of biological products with good specificity,accuracy and reproducibility.
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@#Objective To develop and verify a double antibody sandwich ELISA detection method for the determination of ovalbumin(OVA),in order to determine the OVA content in influenza vaccines.Methods The rabbit anti-OVA polyclonal antibody was used as coating antibody and HRP labeled rabbit anti-OVA polyclonal antibody as detection antibody to develop a double antibody sandwich ELISA for OVA.The antibody concentration(2,1,0.5 and 0.25 pg/mL) for coating,enzyme-labeled antibody concentration(0.5,0.25 and 0.125 μg/mL),and kinds of blocking reagent(blocking with1% BSA,blocking with 2% BSA,blocking with 1% BSA and 1% sucrose,and blocking with 2% BSA and 2% sucrose,using nonblocking as control) were optimized,and the Cut-off value was determined as the judgment standard.The developed method was verified for the linear range and detection limit,specificity,repeatability and accuracy.Results The optimum detection conditions were as follows:the concentration of coating antibody was 1 μg/mL,the concentration of enzyme-labeled antibody was 0.25 μg/mL;The blocking reagent was 2% BSA and 2% sucrose;The Cut-off value was 0.051 66.The linear range of the method was 5～0.313 ng/mL,and the detection limit was 0.078 ng/mL;It did not react with influenza virus,bovine serum albumin(BSA) and Vero cell supernatant;The intraplate and interplate coefficient of variation(CV) were between 2.562%～13.887% and 4.000%～16.497% respectively;The coincidence rate between the results of this method and the Germany SERAMUN OVA quantitative test kit ranged from 93.79% to 107.05%.Conclusion The developed OVA double antibody sandwich ELISA has good specificity,repeatability,linear range and accuracy with convenience and lower cost,which might be used for the quantitative detection of OVA.
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Objective:To established a method for the detection of soluble programmed death ligand 1 (PD-L1) protein in serum based on the poly nanoantibody of lumazine synthase(LS).Methods:A dual nanobody-based sandwich ELISA was established with a competitive ELISA to screen nanobodies recognizing different epitopes of PD-L1 as paired antibodies. To improve sensitivity, PD-L1 nanobody P3C8 and lumazine synthase(LS) were fused, and nanobodies were obtained in polymeric forms as sPD-L1 protein captures, so as to develop an LS-displayed polymeric nanobody-based sandwich ELISA (LSNbs-ELISA) method to detect sPD-L1.Results:Compared with the Nbs-ELISA method, the LSNbs-ELISA method is approximately 11-fold more sensitive for sPD-L1 detection. The limit of detections (LODs) of Nbs-ELISA and LSNbs-ELISA for sPD-L1 in serum were 2.87 ng/ml and 0.255 ng/ml, respectively. Both assays were highly specific for the detection of sPD-L1 and did not react with structure-related proteins PD-1, CD27, CD70, CD137, and CD147 when spiked into the human serum.Conclusions:The Nbs-ELISA and LSNbs-ELISA assays both have high sensitivity and specificity for detecting sPD-L1 in serum and could have potential clinical applications.
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Objective:To establish a double antibody sandwich ELISA for detecting the specific antigen of Seoul virus (SEOV) L99 strain and to provide a means for antigen detection in the development, production and verification of vaccine against hemorrhagic fever with renal syndrome (HFRS).Methods:Monoclonal antibodies (McAbs) aganist L99 virus were induced in mice using four hybridoma cell lines and purified by Protein-A affinity chromatography. The purity, titer and specificity of McAbs were determined by SDS-PAGE, indirect ELISA and Western blot, respectively. Four McAbs were paired with each other and the additivity indices of paired McAbs were analyzed. After labeling McAbs with horseradish peroxidase (HRP), the concentrations of the coated and labeled antibodies were optimized by orthogonal test, and then a double antibody sandwich ELISA for virus antigen detection was established. Type Ⅱ HFRS inactivated vaccine standard was used as a quantitative standard to verify the sensitivity, linearity, specificity, accuracy and precision of the developed method. The applicability of the method was verified by testing three batches of vaccine stock solutions.Results:Four McAbs were at titers of greater than 1∶10 6 and their purity was all greater than 98%. The McAbs secreted by 1D5, 3A4 and 5B7 cells could specifically recognize the nucleocapsid protein of SEOV L99. There was cross-reaction between McAb secreted by 1D5 cells and Hantaan virus PS-6. The McAbs secreted by 3A4 and 1D5 were used as coating and labeling antibodies based on the results of antibody pairs. The working concentrations of the coating antibody and the horseradish peroxidase (HRP)-labeled antibody were 20 μg/ml and 1∶4 000, respectively. The minimum detection limit of the established method for the detection of SEOV L99 antigen was 0.078 1 μg/ml, and the linear range was 0.078 1-2.500 0 μg/ml with a R2 value of more than 0.99. There was no cross reaction with other HFRS vaccine. The virus antigen recovery rate was between 95.8% and 108.7%, and the coefficients of variation of precision was less than 10%. Three batches of Type II HFRS inactivated vaccine stocks were detected by this method and the results was dose-dependent. Conclusions:This study successfully established a double antibody sandwich ELISA method for specific detection of SEOV L99 strain antigen in the production of bivalent HFRS vaccines produced from hamster kidney cells.
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Clostridium difficile is an important zoonotic intestinal pathogen, which is widely present in humans and a variety of animals. The ST11 type C. difficile is one of the most widespread and harmful subtypes in the world. As a large country in pig farming, China lacks efficient methods for detecting C. difficile of porcine origin, leaving hidden dangers for the prevention and control of C. difficile. The aim of this study was to develop a specific and sensitive double-antibody sandwich ELISA for the epidemiological investigation of ST11 type C. difficile of porcine origin. Firstly, a 97 kDa receptor binding domain (RBD) was expressed in a prokaryotic host and purified. A hybridoma cell line AE2D3 capable of stably secreting monoclonal antibody targeting the RBD was screened, and the antibody subtype was determined to be IgG2b (κ). Secondly, a double antibody sandwich ELISA method was developed, where the monoclonal antibody targeting the RBD was used as a detection antibody, and the rabbit polyclonal antibody was used as a capture antibody. The chessboard method was used to determine the matching concentration of the capture antibody and the detection antibody, the antigen coating conditions, the blocking conditions, the incubation conditions for detection antibody and samples to be tested, as well as the reaction conditions of HRP-conjugated and reaction conditions of TMB chromogenic solution. The negative cutoff OD450 was 0.152, and no cross-reaction with 13 strains of non-ST11 type C. difficile was found. The minimum detection concentration of RBD was 8.83 ng/mL. This specific and sensitive double-antibody sandwich ELISA provides a reliable serological detection method for epidemiological investigation of the ST11 type C. difficile in pig industry.
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Animals , Antibodies, Monoclonal , Bacterial Proteins/genetics , Bacterial Toxins , Clostridioides difficile , Enzyme-Linked Immunosorbent Assay , Hybridomas , SwineABSTRACT
GeXIVA[1,2] is a new type of conotoxin recently discovered in the transcriptome of Conus generalis and it is expected to be used clinically as a new type of analgesic. This study established and verified a sandwich enzyme-linked immunosorbent assay method for the marine drug GeXIVA[1,2] in the plasma of rats and Beagle dogs. The mouse monoclonal antibody 4B2 and biotin-labeled rabbit polyclonal antibody 2# were developed. The checkerboard method was used to optimize the antibody pairing concentration, minimum dilution ratio, incubation temperature, and incubation time to establish an antibody sandwich ELISA detection method. Verify the established testing methods. The established ELISA method has a quantitative range of 1.25-80 ng·mL-1 in rat and Beagle plasma. The precision, accuracy, selectivity, specificity, stability, dilution linearity, and hook effect all meet the requirements for biological sample analysis. All the procedures for the animal experiments were approved by the Animal Ethics Committee of the Institute (Permit Number: IACUC-DWZX-2020-698). This method can support the preclinical pharmacokinetic study of the marine drug GeXIVA.
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Objective@#To establish a method for detection of chikungunya virus(CHIKV) antigen.@*Methods@#CHIKV virus like particle(VLP), that contains all structural proteins, was prepared by baculovirus expression system. Mice and rabbits were immunized with the VLP to develop antibodies against CHIKV. A double antibody sandwich ELISA was established for detection of CHIKV antigens. The concentrations of the antibodies used and the reaction conditions were optimized. The detection limit and repeatability of the ELISA was evaluated.@*Results@#The sensitivity and specificity was estimated by 10 mimicking CHIKV sera, 90 health person sera, 40 other virus infected sera. It was show that the specificity of DAS-ELISA was 100%, the detection limit was 10 TCID50, the coefficients of variation (CV) within plate was <5%, the CV of different plates was <10%.@*Conclusions@#The double antibody sandwich ELISA established in this study can be used to detect the CHIKV antigen in acute phase serum of patient and provide a method for detection of CHIKV.
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This study was aimed to develop a sandwich ELISA kit for the diagnosis of bovine tuberculosis.And it was applied and evaluated in the quarantine of bovine tuberculosis.We established a bovine IFN-γ release method in vitro and developing three batches of kits.The sensitivity,repeatability and retention period of the kit were all evaluated.Totally 961 serum samples were tested using the developed sandwich ELISA kit tuberculin skin test and a commercial ELISA kit.Our results showed that the detection limit of this ELISA was 8.21 mg/mL.The repeatability tests showed good reproducibility in the intraassay and inter-assay.At the same time,the retention period of the kit was more than 12 months.Compared with the tuberculin skin test,the positive coincidence rate was 70.59％ and the negative coincidence rate was 99.20％,while the total coincidence rate was 98.44％.And compared with the BOVIGAMTM kit,the positive coincidence rate was 91.30％ and the negative coincidence rate was 99.78％,while the total coincidence rate reached 99.58％.At the same time,the sensitivity and specificity of the sandwich kit were 85.00％ and 100％,respectively.We established a bovine IFN-γ release method in vitro and developing corresponding kits successfully have a good application prospect.
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La fasciolosis es una parasitosis cosmopolita de importancia médico-veterinaria ocasionada por Fasciola hepatica, que afecta al ganado ovino, caprino y vacuno; y accidentalmente al hombre ocasionando una infección endemo-epidémica de difícil diagnóstico. El objetivo fue desarrollar un ELISA sándwich indirecto, empleando 3 anticuerpos, para identificar antígenos de secreción-excreción de Fasciola hepatica (ESFh). Para el ELISA se emplearon anticuerpos policlonales de ratón anti ESFh como anticuerpos de captura, anticuerpos policlonales de conejo anti ESFh como anticuerpos de detección, a las concentraciones de 10 y 5 μg/mL, respectivamente. Como conjugado se emplearon anticuerpos monoclonales de ratón anti-inmunoglobulinas totales de conejo ligado a peroxidasa 1/1000). Se analizaron 31 muestras de heces de ganado ovino y los resultados se compararon con los obtenidos por el examen coproparasitológico directo (CD) y contrainmunoelectroforesis (CIEF). El límite de detección obtenido para ELISA sándwich indirecto fue 100 ng/mL. La prueba presentó una sensibilidad de 100%, especificidad de 96.6% y valores predictivos positivos y negativos de 50% y 96.6% respectivamente; con relación al examen CD. Al comparar ELISA tipo sándwich indirecto con CIEF se obtuvo una especificidad de 93.5% y un valor predictivo negativo del 100%. Se concluye que la prueba de ELISA sándwich indirecto diseñada es capaz de detectar antígenos metabólicos en muestras de heces de ovino y se puede utilizar para el diagnóstico Fasciola hepatica.
Fasciolosis is a cosmopolitan parasitosis medical-veterinary importance caused by Fasciola hepatica, which affects sheep, goats and cattle; and it affects man accidentally causing an epidemic-endemic infection difficult to diagnose. The aim was to develop an indirect sandwich ELISA with 3 antibodies for detecting excretory-secretory antigens of Fasciola hepatica (ESFh). For the development of indirect sandwich ELISA were used, as capture antibody, mouse polyclonal antibodies anti ESFh and polyclonal antibodies rabbit anti-ESFh as detection antibody, at the concentrations of 10 and 5 μg/mL respectively. The conjugate used was mouse monoclonal anti- total immunoglobulins rabbit linked to peroxidase (1/1000). Were analized 31 sheep fecal samples, and the results were compared with those obtained by direct coproparasitological examination (DC) and counterimmunoelectrophoresis (CIEP). The detection limit obtained for indirect sandwich ELISA was 100 ng/mL. The test had a 100% sensitivity, 96.6% specificity, positive and negative predictive values of 50% and 96.6% respectively, in relation to DC test. Comparing with CIEP the specificity obtained for indirect sandwich ELISA was 93.5% and a negative predictive value of 100%. We concluded that indirect sandwich ELISA designed is able to detect metabolic antigens in ovine feces samples and can be used for Fasciola hepatica diagnosis.
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Objective To establish a double-antibody sandwich ELISA for the rapid detection of shiga toxin typeⅡ ( StxⅡ) in shiga toxin-producing Escherichia coli ( STEC) infection. Methods A pool of murine hybridomas was used to screen out the optimal antibody pair for the establishment of double-anti-body sandwich ELISA. The established ELISA system was used to detect StxⅡin the culture supernatants of 16 clinical strains of STEC. Specificity and sensitivity of the established ELISA system were also evaluated. Results Two antibodies, S2D8 and S2C6, were successfully screened out, based on which the double-anti-body sandwich ELISA was set up. StxⅡand its variants rather than StxⅠwas detected in the culture super-natants of STEC with a lowest detection limit of 4 ng/ml. Its performance was consistent with that of commer-cial colloidal gold test kit, indicating the characteristics of good specificity and sensitivity. Conclusion The S2D8/S2C6-based ELISA laid a foundation for researches which designates the shiga toxin as a potential can-didate on the diagnosis and therapy of STEC infection.
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Objective:To establish the detection method of double-antibody sandwich ELISA about CYFRA 21-1 in human ser-um.Methods:The paired antibody were screened among four strains mAbs of CYFRA 21-1, which was marked by sodium periodate method.The detecting method of double antibody sandwich ELISA was optimizted , and evaluated by specificity , stability and sensitivi-ty.Results:The results showed that a paired of antibody , which was 2F9 as the coated antibody and 6F11 as the labeled antibody, was selected from four mAbs .It was the optimum condition of double antibody sandwich ELISA that the coating antigen concentration of 2F9 was 0.50 μg/ml, while the labeled antibody of 6F11 was diluted 6 000 times.The linear range of standard curve was 0.7-25 ng/ml with r2 =0.990 8, while the limit of detection was 0.666 8 ng/ml, the recovery rate was 98.14%.The cross-reactions with the oth-er analogues in serum were less than 0.1%.The coefficient of variation in group (n=10) was 6.8%, whereas coefficient of variation among group(n=5) was 11.4%.The correlation compared with other foreign ELISA kit was 91.42%.Conclusion:In brief, we suc-cessfully established the method of double antibody sandwich ELISA detecting CYFRA 21-1 level in human serum , laying the foundation for the production of CYFRA21-1 ELISA kit.
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PURPOSE: Tuberculosis (TB) is a major infectious disease and is responsible for two million deaths annually. For the identification and quantitation of Mycobacterium tuberculosis (M. tuberculosis), a causative agent of TB, a sandwich enzyme-linked immunosorbent assay (ELISA) against the MPT64 protein of M. tuberculosis, an antigen marker of the M. tuberculosis complex, was developed. MATERIALS AND METHODS: The MPT64 protein was expressed, and anti-MPT64 monoclonal antibodies were prepared. A sandwich ELISA was established using recombinant MPT64 protein and anti-MPT64 monoclonal antibodies. The sandwich MPT64 ELISA was evaluated using reference and clinical mycobacterial strains. RESULTS: The sandwich MPT64 ELISA detected MPT64 protein from 2.1 ng/mL to 250 ng/mL (equivalent to 1.7x10(4) CFU/mL and 2.0x10(6) CFU/mL). All 389 clinical M. tuberculosis isolates tested positive in the sandwich MPT64 ELISA (sensitivity, 100%), and the assay showed no cross reactivity to any tested nontuberculous mycobacterial strain (specificity, 100%). CONCLUSION: The sandwich MPT64 ELISA is a highly sensitive and quantitative test for MPT64 protein, which can identify M. tuberculosis.
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Antigens, Bacterial/analysis , Enzyme-Linked Immunosorbent Assay/methods , Mycobacterium tuberculosis/immunologyABSTRACT
A field applicable diagnostic technique, the dipstick assay, was evaluated for its sensitivity and specificity in diagnosing human Schistosoma mansoni infection. A monoclonal antibody (mAb) against S. mansoni adult worm tegumental antigen (AWTA) was employed in dipstick and sandwich ELISA for detection of circulating schistosome antigen (CSA) in both serum and urine samples. Based on clinical and parasitological examinations, 60 S. mansoni-infected patients, 30 patients infected with parasites other than schistosomiasis, and 30 uninfected healthy individuals were selected. The sensitivity and specificity of dipstick assay in urine samples were 86.7% and 90.0%, respectively, compared to 90.0% sensitivity and 91.7% specificity of sandwich ELISA. In serum samples, the sensitivity and specificity were 88.3% and 91.7% for dipstick assay vs. 91.7% and 95.0% for sandwich ELISA, respectively. The diagnostic efficacy of dipstick assay in urine and serum samples was 88.3% and 90.0%, while it was 90.8% and 93.3% for sandwich ELISA, respectively. The diagnostic indices of dipstick assay and ELISA either in serum or in urine were statistically comparable (P>0.05). In conclusion, the dipstick assay offers an alternative simple, rapid, non-invasive technique in detecting CSA or complement to stool examinations especially in field studies.
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Animals , Humans , Antibodies, Helminth , Antibodies, Monoclonal , Antigens, Helminth/blood , Diagnostic Tests, Routine/methods , Immunoassay/methods , Parasitology/methods , Point-of-Care Systems , Schistosoma mansoni/immunology , Schistosomiasis mansoni/diagnosis , Sensitivity and SpecificityABSTRACT
The present study describes the frequency of Foot and Mouth Disease (FMD) virus serotypes (O,A and Asia-1) in major regions (all provinces) of Pakistan using Indirect Sandwich ELISA.Also,spatial distribution of various FMD serotypes and their comparison is discussed.A total of 590 samples (Epithelial tissue) have been analyzed during a period of five years (2005-2009).Out of 590 samples,180 were found positive,giving an overall confirmation of FMDV about 33.2 ％.Of the prevalent serotypes,FMDV ‘O’ serotype caused most outbreaks (20.7 ％),followed by serotype A (6.6 ％) and serotype Asia-1 (4.6 ％) while there was no positive case oftype ‘C’.The study clearly showed that the disease was more frequent in the agro-climatic zones than in hilly areas.Based on the data of 590 samples (＞50 outbreaks),the overall prevalence of FMDV in cattle and buffaloes in Pakistan was 33.2 ％,while in cattle alone,it was 37.1％,higher than in buffalo (28.7 ％).There were eight cases of mixed serotypes infection,indicating the presence of endemic state of disease.Another significant feature was the change over time.In phase-I (2005-2007),there was an overall prevalence of 29.4 ％,while the occurrence of the serotype O,A and Asia-1 was 20.4 ％,2.9 ％ and 4.7 ％,respectively.During phase-II (2008-2009),the overall prevalence was 59.21％,while those of serotype O,A and Asia-1 were 22.4 ％,31.6 ％ and 4.0 ％,respectively.This clearly indicated a shift from serotype O to A,which may help to explain the occurrence of more severe outbreaks,despite vaccination.
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ObjectiveTo develop an ELISA method for quantitative determination of enterovirus 71 (EV71) antigen.The method can be applied to detect EV71 antigen contents and analyze the correlation between immunogenicity and immunoprotection.It also can be used for tissue culture infective dose( TCID50 ) assay.MethodsA double antibody sandwich ELISA method was developed for quantitative determination of EV71 antigen on the basis of the high-affinity neutralizing monoclonal antibodies ( K8G2 and Y8H2-HRP).This method was compared with microscopic observation for the detection of EV71 TCID50.The correlation was analyzed between the specific activity of EV71 antigen and the EV71 neutralizing antibody titer in immune serum.ResultsThe linear range of this method was 0.125-4.0 U/ml and the R2 value was 0.9911.The reagent did not react with other antigens except EV71 antigen.The recovery ratio of this method was 0.89-1.16.The coefficient of variation was less than 15％.The heat recovery rate was above 85％ when the reagent was in 37℃ for 9 days.There was a good correlation in TCID50 of EV71 between this method and microscopic observation,r=0.990.The specific activity of EV71 antigen had positive correlation with the neutralization titer of immune serum in 21 EV71 strains,r=0.930.ConclusionThe quantitative ELISA method for EV71 antigen was developed,which could be used to detect EV71 antigen contents and analyze TCID50.The specific activity of EV71 antigen detected by the method could be used to evaluate the immunoprotection of the vaccine potency test.
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Objective To detect infection of Angiostrongylus cantonensis and examine effection of treatment to prepare monoclonal antibodies(McAbs). Methods Six-week-old BALB/c mice were imrnunized by the intraperitoneal injection of e/s antigens of Angiostrongylus cantonensis. Fusion of splecn cells from immunized mice with prepared SP2/0-Ag14 myeloma cells was performed in RPMI 1640. Fused cells were suspended in RPMI 1640 containing 1% HAT and 20% fetal calf serum and dispensed into 96-well cell culture plates. The supernatants of clones were screened by ELISA with sera of patients of angiostrongyliasis.Distribution of cohere antigen of 12D5 and 21B7 monoclonal antibodies was analyzed with immunohistochemistry. Two McAbs ( 12D5 and 21B7) were applied to detect the circulating antigen (CAg) in the sera of rats infected with A. cantonensis and angiostrongyliasis patients respectively by double antibody sandwich ELISA.Results 12D5 McAb was identified as IgG1 and 21 B7 McAb was IgM. Western blot result showed two McAbs could used to identified 55 × 103 protein of adult worms of A. cantonensis. Cohere antigen of 12D5 and 21B7 monoclonal antibodies were distributed on intestine surface of A. cantonensis. The detection rates of CAg in the sera of infected rats 100% (48/48), the detection rates of CAg in the sera of angiostrongyliasis patients was 100% (32/32). No cross-reaction to sera of patients with other infection of parasites, such as clonochiasis, fasiolopsiasis, ancylostomiasis, trichinosis, anisakiasis as well as schsitosomiasis, and health srea did not reacted with 12D5 and 21B7 McAbs,and detaction rate of antibody of angiostrongyliasis patients only reached 75% (24/32) with antigen of A. cantonensis. Conclusion Cohere antigen of 12D5 and 21B7monoclonal antibodies were antigens of enteric epithelium. Sandwich ELISA with 12D5 and 21B7 McAbs showed high specificity act as detecting CAg of A. cantonensis in sera of infection animal and patients. It is apparent that Sandwich ELISA with 12D5 and 21 B7 is not only rapid and simple without requirement of special instrument, but also rather sensitive and specific for the detection of current infection with A. cantonensis.
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A monoclonal antibody (MAb) specific for the bluetongue virus (BTV) group specific antigen (VP7) was characterized for its reactivity with purified virus and recombinant BTV VP7 (rVP7) protein and its suitability for use in the sandwich ELISA. The MAb, designated as 5B5 was specific to VP7 and belongs to IgG2a subclass and was selected for the development of the sELISA in this study. The MAb had a titer of 1:25 with BTV and 1:2 with the rVP7 protein. The sELISA is based on capturing of BTV antigen with VP7 specific MAb followed by detection using BTV polyclonal antiserum raised in rabbits. The assay was evaluated with six cell culture adapted serotypes of BTV that have been isolated from India, 1, 2, 15, 17, 18 and 23. The assay could detect BTV antigen as early as day 8 in blood. It was also successfully applied for the detection of BTV group specific antigen in clinical samples of blood, washed RBCs, buffy coat and plasma. A total of 102 field samples from animals, suspected of being infected with BTV, were tested and 29.42% were positive. The blood samples were also amplified in cell culture which improved the sensitivity of the assay. Results confirmed that the sELISA is rapid and specific.
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A double antibody sandwich ELISA for quantitative analysis of recombinant fusion protein IL-2-HSA was constructed using a polyclonal antibody to human IL-2 for capture and a monoclonal antibody to HSA with HRP-labeled conjugate for detection.The optimal concentration of the first coating antibody and detection antibody were 2 μg/mL and 0.5 μg/mL,respectively.Regression equation of the linear calibration curve was:y = 0.442 9 x-1.143 3 with a correlation coefficient of 0.996 6,and the linear detection ranged from 39.06 ng/mL to 1 250 ng/mL.Recovery from the supernatant of fermentation broth was 98.13% to 102.94%.The specificity assay indicated that it had little cross-reactions with IL-2 and HSA.The soundness analysis suggested that fermentation broth,mouse serum and dilution had no influence on the method.The present method can be used in the studies on fermentation,purification and clinical diagnosis.
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Objective To prepare monoclonal antibody in mice so as to develop an ELISA method for diagnosis of Toxoplasma gondii infection during the initial stage. Methods The mice were immunized by combining routine and intrasplenic immunization with recombinant SGA1 antigen. B lymphocyte hybridization technique was applied to prepare the anti-SAG1 McAbs. Positive clones were screened using ELISA and subcloned to establish cell lines. Ascites was induced to produce the McAbs. Then the McAbs were purified by protein G chromatograph column. The specificity of McAbs was identified by Western blot and sandwich-ELISA. Sensitivity of the McAbs was determined using sandwich-ELISA. Comparasion was carried out between PCR and sandwich-ELISA method. Results Two positive clones were obtained and named as 3B6, 10C4, both could identify the native and recombinant SAG1 antigens. The sensitivity of 3B6, 10C4 was 31.3 ng and 62.5 ng, respectively. There was no cross reaction between the McAbs and positive sera from patients with schistosomiasis, ancylostomiasis or malaria. By using PCR and ELISA, the positive infection rate of T. gondii was 63.2% and 47.4%, respectively. Conclusions Therefore, mouse anti-rSAG1 antigen McAbs have been prepared successfully and primarily applied to early stage diagnosis of T. gondii infection.
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Objective To develop a double antibody sandwich ELISA for quantitatively detecting Japanese encephalitis virus(JEV) antigen.Methods The anti-JEV polyclonal antibodies were used to coat ELISA plates.Anti-JEV monoclonal antibodies were used as enzyme-labeled conjugate.A standard curve based on known amounts of JEP antigen was established by the ELISA.Various parameters of the assay were analyzed.Results The optimal linear range was 12.5～200 U/ml(r=0.9989).The quantitation limit was 12.5 U/ml.The recovery rate for the accuracy test was 85.0%～103.3%.The coefficients of variation for intra-assay and inter-assay precision were 4.3%and 5.5%respectively.No cross-reaction was observed with HAV vaccine,influenza vaccine,Vero cell Iysates,newborn bovine serum,or human albumin.Conclusions The data indicate that the ELISA developed in this study has high specificity,precision, accuracy,and stability.The assay should be suitable for quantitative determination of JEV antigen in various vaccine products.