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1.
A monoclonal antibody-based sandwich direct ELISA (MSD-ELISA) method was previously developed for foot-and-mouth disease (FMD) viral antigen detection. Here we evaluated the sensitivity and specificity of two FMD viral antigen detection MSD-ELISAs and compared them with conventional indirect sandwich (IS)-ELISA. The MSD-ELISAs were able to detect the antigen in saliva samples of experimentally-infected pigs for a longer term compared to the IS-ELISA. We also used 178 RT-PCR-positive field samples from cattle and pigs affected by the 2010 type-O FMD outbreak in Japan, and we found that the sensitivities of both MSD-ELISAs were about 7 times higher than that of the IS-ELISA against each sample (P<0.01). In terms of the FMD-positive farm detection rate, the sensitivities of the MSD-ELISAs were about 6 times higher than that of the IS-ELISA against each farm (P<0.01). Although it is necessary to conduct further validation study using the other virus strains, MSD-ELISAs could be appropriate as a method to replace IS-ELISA for FMD antigen detection.  相似文献   

2.

Background

Fascioliasis is a worldwide parasitic disease of domestic animals caused by helminths of the genus Fasciola. In many parts of the world, particularly in poor rural areas where animal disease is endemic, the parasite also infects humans. Adult parasites reside in the bile ducts of the host and therefore diagnosis of human fascioliasis is usually achieved by coprological examinations that search for parasite eggs that are carried into the intestine with the bile juices. However, these methods are insensitive due to the fact that eggs are released sporadically and may be missed in low-level infections, and fasciola eggs may be misclassified as other parasites, leading to problems with specificity. Furthermore, acute clinical symptoms as a result of parasites migrating to the bile ducts appear before the parasite matures and begins egg laying. A human immune response to Fasciola antigens occurs early in infection. Therefore, an immunological method such as ELISA may be a more reliable, easy and cheap means to diagnose human fascioliasis than coprological analysis.

Methodology/Principal findings

Using a panel of serum from Fasciola hepatica-infected patients and from uninfected controls we have optimized an enzyme-linked immunosorbent assay (ELISA) which employs a recombinant form of the major F. hepatica cathepsin L1 as the antigen for the diagnosis of human fascioliasis. We examined the ability of the ELISA test to discern fascioliasis from various other helminth and non-helminth parasitic diseases.

Conclusions/Significance

A sensitive and specific fascioliasis ELISA test has been developed. This test is rapid and easy to use and can discriminate fasciola-infected individuals from patients harbouring other parasites with at least 99.9% sensitivity and 99.9% specificity. This test will be a useful standardized method not only for testing individual samples but also in mass screening programs to assess the extent of human fascioliasis in regions where this zoonosis is suspected.  相似文献   

3.
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 spec...  相似文献   

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6.
现已证实,Nodal参与了肿瘤恶性生物学过程,但对其高敏感检测法尚未建立。采用基因工程表达人源Nodal作为抗原免疫BALB/c小鼠,通过经典PEG诱导的细胞融合技术筛选出针对Nodal的特异性单克隆抗体7株。夹心ELISA确证7株抗体组成了15种可配对的抗体对。经筛选后选取抗体对AF12-DG5建立标准化夹心ELISA法,结合生物素-亲和素检测系统,DG5抗体标记生物素,采用链亲和素与辣根过氧化物酶标记的生物素(HRP-Biotin)按质量比4∶1预先混合孵育的ABC混合物进行检测,以提高ELISA法的灵敏度。棋盘滴定确定抗体工作最佳浓度为:捕获抗体(AF12)2μg/ml,检测抗体(生物素化DG5)2μg/ml。此条件下的夹心ELISA法线性范围为0~3 000pg/ml,检测限为68pg/ml,平均回收率为99.6%,精密度准确度良好。以正常人血清作为阴性对照,使用该夹心ELISA法测定结直肠癌、鼻咽癌和胆囊癌患者血清,发现三种肿瘤患者血清与正常人血清中的Nodal浓度均存在明显的统计学差异,可作为临床使用参考。  相似文献   

7.
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.  相似文献   

8.
The helminth parasite Fasciola hepatica secretes cathepsin L cysteine proteases to invade its host, migrate through tissues and digest haemoglobin, its main source of amino acids. Here we investigated the importance of pH in regulating the activity and functions of the major cathepsin L protease FheCL1. The slightly acidic pH of the parasite gut facilitates the auto-catalytic activation of FheCL1 from its inactive proFheCL1 zymogen; this process was ∼40-fold faster at pH 4.5 than at pH 7.0. Active mature FheCL1 is very stable at acidic and neutral conditions (the enzyme retained ∼45% activity when incubated at 37°C and pH 4.5 for 10 days) and displayed a broad pH range for activity peptide substrates and the protein ovalbumin, peaking between pH 5.5 and pH 7.0. This pH profile likely reflects the need for FheCL1 to function both in the parasite gut and in the host tissues. FheCL1, however, could not cleave its natural substrate Hb in the pH range pH 5.5 and pH 7.0; digestion occurred only at pH≤4.5, which coincided with pH-induced dissociation of the Hb tetramer. Our studies indicate that the acidic pH of the parasite relaxes the Hb structure, making it susceptible to proteolysis by FheCL1. This process is enhanced by glutathione (GSH), the main reducing agent contained in red blood cells. Using mass spectrometry, we show that FheCL1 can degrade Hb to small peptides, predominantly of 4–14 residues, but cannot release free amino acids. Therefore, we suggest that Hb degradation is not completed in the gut lumen but that the resulting peptides are absorbed by the gut epithelial cells for further processing by intracellular di- and amino-peptidases to free amino acids that are distributed through the parasite tissue for protein anabolism.  相似文献   

9.
Recombinant Fasciola cathepsin L-1 (rCatL1) was evaluated in enzyme-linked immunosorbent assay (ELISA) for the serodiagnosis of human fasciolosis in Japan. Quality characteristics of the test were accessed by receiver operating characteristic (ROC) analysis, with sera from fasciolosis patients (n = 10), patients with no evidence of parasitic infections (n = 29), and patients with other helminth infections (n = 119). Both the sensitivity and specificity of the test achieved 100% with the control samples. To test the performance of the assay in an authentic situation, 311 serum samples, which had been sent to our laboratory for the diagnosis of parasitic infections from January 2018 to February 2019, were re-assessed using the rCatL1 ELISA. In this case, the sensitivity of the rCatL1 ELISA was 100%, giving positive results to all fasciolosis sera (n = 7), and the specificity was 99.0%, in which three of the 304 non-fasciolosis samples were judged positive. Careful re-examination of the laboratory data and medical imaging of these three patients revealed that one of the patients, who had been diagnosed as having larva migrans syndrome, was judged to be infected with Fasciola, in addition to ascarid nematodes. Thus the true specificity of the assay in the authentic reached 99.3% (302/304). As the rCatL1 ELISA exhibited a highly significant positive likelihood ratio (152.0) and negative likelihood ratio (0.0), calculated from the 311 sample data, this rCatL1 ELISA can be used for routine screening and definitive diagnosis test for fasciolosis in reference laboratories.  相似文献   

10.
双抗体夹心ELISA与NIH法在狂犬病疫苗抗原检测中的比较   总被引:4,自引:0,他引:4  
朱蓉  徐葛林  孙文  秦莉  卢影 《中国病毒学》2005,20(6):623-625
通过用单克隆抗体制备双抗体夹心ELISA,快速检测狂犬病疫苗中狂犬病毒糖蛋白(G)的含量,将狂犬病疫苗的检定时间由28天缩短至2个工作日,以此缩短疫苗库存待检时间,提高疫苗的生产和销售效率,并最终替代NIH动物法.将待检的狂犬病疫苗样品在同一性别12~14g昆明鼠体内作效力检定试验(NIH),同时用双抗体夹心ELISA检测狂犬病疫苗中狂犬病毒G蛋白含量,用Microsoft Office Excel做出标准品和各样品疫苗的线性关系图并计算出疫苗效力值E-NIH.结果用双抗体夹心ELISA所得的E-NIH与对应的小鼠效力试验所得结果M-NIH之间呈正相关性;同一批狂犬病疫苗分次测得E-NIH值在2.41~5.85之间,而相应的M-NIH值在5.11~10.19之间.从而得出E-NIH与相应的M-NIH之间存在明显的线性关系;与NIH法比较,ELISA具有重复性好、成本低、快速等优点;用双抗体夹心ELISA替代小鼠效力试验是可能并可行的.  相似文献   

11.
通过用单克隆抗体制备双抗体夹心ELISA,快速检测狂犬病疫苗中狂犬病毒糖蛋白(G)的含量,将狂犬病疫 苗的检定时间由28天缩短至2个工作日,以此缩短疫苗库存待检时间,提高疫苗的生产和销售效率,并最终替代 NIH动物法。将待检的狂犬病疫苗样品在同一性别12~14g昆明鼠体内作效力检定试验(NIH),同时用双抗体夹 心ELISA检测狂犬病疫苗中狂犬病毒G蛋白含量,用Microsoft Office Excel做出标准品和各样品疫苗的线性关 系图并计算出疫苗效力值E-NIH。结果用双抗体夹心ELISA所得的E-NIH与对应的小鼠效力试验所得结果M- NIH之间呈正相关性;同一批狂犬病疫苗分次测得E-NIH值在2.41~5.85之间,而相应的M-NIH值在5.11~ 10.19之间。从而得出E-NIH与相应的M-NIH之间存在明显的线性关系;与NIH法比较,ELISA具有重复性好、 成本低、快速等优点;用双抗体夹心ELISA替代小鼠效力试验是可能并可行的。  相似文献   

12.
A method of the competitive immunochromatographic assay of the pesticides 2,4-D (2,4-dichlorophenoxyacetic acid) and simazine (2-chloro-4,6-bis(N-ethylamino)-1,3,5-triazine) in aqueous samples was developed. Monoclonal antibodies to these pesticides labeled with colloidal gold were used to visualize the results. The sensitivity of the 2,4-D and simazine assay is 12 ng/ml, and the time of analysis is 3–7 min. The method does not differ in sensitivity from the competitive EIA using conjugates of monoclonal antibodies to the pesticides with horseradish peroxidase; however, the time of the EIA is 1.5 h. The immunochromatographic method of the pesticide detection is available and simple and may be recommended for the development of assays of any other low-molecular compounds.  相似文献   

13.
实验旨在建立牛重组IFN-γ(BovIFN-γ)的ELISA检测技术,为牛传染病的免疫学诊断提供新方法。PHA刺激体外培养的奶牛外周血白细胞,从培养细胞中提取总RNA,经过RT-PCR扩增出BovIFN-γ基因cDNA,进一步克隆至pET28a,转化大肠杆菌,经IPTG诱导,表达出预期大小(18kD左右)组氨酸标记蛋白,经鉴定为BovIFN-γ;以纯化的重组BovIFN-γ为免疫原,应用淋巴细胞杂交瘤技术,获得4株能稳定分泌抗BovIFN-γ单克隆抗体的细胞株,分别命名为A7、A10、G6与G10。免疫球蛋白亚类鉴定证明杂交瘤细胞所分泌的抗体均为IgG1,腹水效价在1∶210×100~1∶211×100之间。Western-blot分析显示,4株单抗均能特异性结合重组BovIFN-γ。ELISA试验表明,4株单抗只与融合蛋白BovIFN-γ反应,而不与非相关性蛋白Ag85B、ESAT-6-CFP-10、GM-CSF等发生反应。选取A10细胞株分泌的单克隆抗体、纯化的多克隆抗体及辣根过氧化物酶(HRP)标记的羊抗兔IgG,建立了检测BovIFN-γ的双抗体夹心ELISA方法。实验结果表明,此方法检测敏感性达到2ng/mL,特异性良好,为进一步建立灵敏、特异的病原感染诊断方法奠定了基础。  相似文献   

14.
Sheep fasciolosis is a devastating burden for the livestock industry. We herein report on immunodiagnosis of fasciolosis, and significant protection of sheep against challenge infection with Fasciola gigantica following immunization with a peptide based on the H-Asp(110)-Lys-Ile-Asp-Trp-Arg-Glu-Ser-Gly-Tyr-Val-Thr-Glu-Val(123)-OH (Fas14p) sequence of F. gigantica cathepsin L-cysteine proteinase. This sequence was synthesized in three different forms: as N(alpha) acetylated (Ac-Asp(110)-Lys-Ile-Asp-Trp-Arg-Glu-Ser-Gly-Tyr-Val-Thr-Glu-Val(123)-OH, FasAc14p), bearing at the amino-terminus an N(alpha) acetylated cystein (Ac-Cys-Asp(110)-Lys-Ile-Asp-Trp-Arg-Glu-Ser-Gly-Tyr-Val-Thr-Glu-Val(123)-OH, FasAcCys14p), and conjugated to sequential oligopeptide carrier Ac-[Lys-Aib-Gly](4)-OH (Ac-SOC(4)) through an amide bond formed between Val(123) carboxylic group of the epitope and the lysine N(epsilon) groups of the carrier (Ac-[Lys(Fas14p)-Aib-Gly](4)-OH). Ac-[Lys(Fas14p)-Aib-Gly](4)-OH failed to readily discriminate between na?ve and infected sheep. In contrast, the free peptides reproducibly differentiated between parasite-free sheep, sheep infected with parasites other than Fasciola, and experimentally Fasciola-infected sheep. The data together indicated that the peptides might be of considerable use for discriminating between early and late, and low and high burden, sheep infection with F. gigantica. FasAc14p was chosen to determine whether a peptide based on a critical enzymatic site of cathepsin L proteinase may induce protection against challenge infection. Sheep immunization with FasAc14p peptide induced significant expression of interleukin-4 mRNA, and humoral antibodies that bound to molecule(s) on the intact surface membrane of newly excysted juvenile worms, and mediated their attrition. The immune responses were associated with significant (P < 0.02) decrease of 23.1% in worm recovery, but with no decrease in the size or maturation of worms recovered.  相似文献   

15.
Using a mouse monoclonal antibody (MAb) 2F raised against Vibrio cholerae non-O1 heat-stable enterotoxin (NAG-ST) which also recognizes a shared epitope of Yersinia enterocolitica heat-stable enterotoxin (Y-ST), a competitive enzyme-linked immunosorbent assay (ELISA) was developed for independent detection of NAG-ST and Y-ST. There was good concordance between the Y-ST ELISA and the suckling mouse assay (SMA) for detection of Y-ST from test strains of Y. enterocolitica, and the Y-ST ELISA can effectively replace the SMA for routine detection of Y-ST. On the contrary, evaluation of the NAG-ST ELISA and the SMA using 139 strains of V. cholerae non-O1 showed discordant results and this was attributed to the presence of the suckling mice active factor(s) such as El Tor hemolysin and to the production of low amounts of NAG-ST. Concentration of culture supernatants of V. cholerae non-O1 followed by heating at 100 C was essential to obtain reproducible results by both the NAG-ST ELISA and the SMA. The ELISA developed in this study can be used for the identification of biologically active strains. While recently genetic methods such as polymerase chain reaction became available and were very reliable and simple techniques, the ELISA in this study has an advantage in detecting biologically toxic gene products of the strains. The genetic methods cannot differentiate silent STa genes which we often encounter in the case of Y. enterocolitica.  相似文献   

16.
目的:为检测血清中HSA-GLP-1融合蛋白整体分子的浓度,建立一种特异、灵敏的定量检测食蟹猴体内HSA-GLP-1融合蛋白浓度的双抗体夹心ELISA的方法。方法:采用双抗体夹心ELISA方法,以GLP-1单克隆抗体为包被抗体、HSA-GLP-1融合蛋白为夹心抗原、anti-HSA-Biotin为检测抗体,用Streptavidin-HRP进行免疫放大,TMB显色。结果:建立了检测HSA-GLP-1融合蛋白的ELISA方法,其线性范围为15.6~1000 ng/mL,最低检测限为15.6 ng/mL,与GLP-1、HSA、IL2-HSA均无交叉反应,板内和板间精密度均小于15%,准确度为±15%,冻融稳定性和稀释稳定性良好。结论:建立的HSA-GLP-1蛋白检测方法符合新生物制品临床前药代动力学研究指导原则要求,可用于HSA-GLP-1融合蛋白在临床前药代动力学试验的定量检测。  相似文献   

17.

Background

Antigen specific release of IP-10 is the most promising alternative marker to IFN-γ for infection with M. tuberculosis. Compared to Interferon-γ release assays (IGRA), IP-10 is released in high levels enabling novel approaches such as field friendly dried blood spots (DBS) and molecular detection.

Aim

To develop a robust IP-10 based molecular assay for the diagnosis of infection with M. tubercuolsis from whole blood and DBS.

Method

We developed a one-step probe based multiplex RT-qPCR assay for detecting IP-10 and IFN-γ mRNA expression from whole blood and DBS samples. The assay was validated and applied for the diagnosis of M. tuberculosis infection in DBS samples from 43 patients with confirmed TB, 13 patients with latent TB and 96 presumed uninfected controls. In parallel, IP-10 and INF-γ levels were measured in Quantiferon (QFT-TB) plasma supernatants.

Results

IP-10 mRNA upregulation was detectable at 4 hours after stimulation (6 fold upregulation) peaking at 8 hours (108 fold upregulation). IFN-γ expression occurred in concert but levels were lower (peak 6.7 fold upregulation). IP-10 gene expression level was significantly higher in patients with tuberculosis (median 31.2, IQR 10.7–67.0) and persons with latent tuberculosis infection (LTBI) (41.2, IQR 9.8–64.9) compared to healthy controls (1.6, IQR 1.1–2.4; p<0.0001). The IP-10 mRNA and protein based tests had comparable diagnostic accuracy to QFT-TB, sensitivity (85% and 88% vs 85%) and specificity (96% and 96% vs 97%, p = ns.).

Conclusion

We developed a rapid, robust and accurate molecular immunodiagnostic test for M. tuberculosis infection. By combining DBS based sample acquisition, mail or currier based sample transport with centralized molecular detection, this immunodiagnostic test concept can reduce the local technological requirements everywhere and make it possible to offer highly accurate immunodiagnostic tests in low resource settings.  相似文献   

18.

Objective

Organophosphorus (OP) pesticides are considered hazardous substances because of their high toxicity to nontarget species and their persistence in the environment and agricultural products. Therefore, it is important to develop a rapid, sensitive, and economical method for detecting OP pesticides and their residues in food and the environment.

Methods

A broad, selective monoclonal antibody (MAb) for organophosphorus pesticides was produced. Based on the MAb, an enzyme linked immunosorbent assay (ELISA) and an immunochromatography assay (ICA) for detecting OP pesticides in different agricultural products were developed using a binding inhibition format on microtiter plates and a membrane strip, respectively.

Results

Under the optimized conditions, the IC50 values of the ELISA ranged from 3.7 to 162.2 ng mL–1 for the 8 OP pesticides. The matrix interferences of Apple, Chinese cabbage, and greengrocery were removed by 40-fold dilution, the recoveries from spiked samples ranged from 79.1% to 118.1%. The IC50 values of ICA for the 8 OP pesticides ranged from 11.8 to 470.4 ng mL−1. The matrix interference was removed from the Chinese cabbage and Apple samples with 5-fold dilution, and the interference was removed from the greengrocery samples with 20-fold dilution. The recoveries from the spiked samples ranged between 70.6 and 131.9%. The established ELISA and ICA were specific selectivity for the 8 OP pesticides.

Conclusions

The established ELISA is a sensitive screening method for the detection of OP pesticides, but the ELISA detection method depends on a laboratory platform and requires a relative long assay time and several steps operation. The established ICA is very useful as a screening method for the quantitative, semi-quantitative or qualitative detection of OP pesticides in agricultural products, and it has advantages over ELISA methods with regard to factors such as the testing procedure, testing time, and matrix interferences, among others.  相似文献   

19.
犬细小病毒病是危害养犬业的重要传染病之一,患病犬难以治愈.单克隆抗体治疗此病效果明显,本文介绍了制备抗CPV-2a单克隆抗体的方法.用纯化的犬细小病毒(canine parvovirus,CPV) 2a型分离株免疫新西兰大白兔和Balb/c小鼠制备抗CPV-2a多克隆抗体及单克隆抗体.经亚克隆得到1H9、2B5、2B7和2C7共4株单抗,Western blotting鉴定单抗的免疫反应性;间接ELISA方法检测单抗的特异性.为了快速对犬细小病毒病作出诊断,建立了CPV-2a双抗夹心ELISA方法.兔多抗作为捕获抗体,鼠单抗作为示踪抗体,辣根过氧化物酶标记羊抗鼠IgG作为检测系统;捕获抗体和示踪抗体最佳稀释度分别为1:800和1:2 000;检测系统最佳稀释度为1:4 000.结果表明:所得4株单抗与pET-32a-VP2蛋白发生特异性反应,且与狂犬病毒(RV)、犬温热病毒(CDV)不交叉反应;建立的双抗夹心ELISA方法对病毒的最低检出量为4.375 μg/mL,与美国RB试剂盒相比,符合率为95%.单抗制备为犬细小病毒病的治疗奠定了基础;双抗夹心ELISA方法的建立为疑似粪便样本提供了简单、快速和可靠的检测手段.  相似文献   

20.
目的 血清抗磷脂酶A2受体抗体IgG (PLA2R-IgG)水平是诊断和治疗特发性膜性肾病(IMN)的重要依据,而目前国内外常规检测手段主要是酶免法。为提升检测的便捷性,同时满足灵敏、宽量程分析需求,本研究构建了一种新的PLA2R-IgG检测技术。方法 采用包裹铕元素的微球示踪,对反应步骤进行选择,对微球制备液的p H、微球-抗体反应比例和反应时间优化,本文基于间接法构建了PLA2R-IgG的荧光定量免疫层析检测方法,并进行了初步临床评价。结果 本方法的灵敏度达0.7 RU/ml,标准曲线方程为y=0.771x-1.437,相关系数0.995,线性测量范围为0.7~1 500 RU/ml,回收率为86.27%~98.98%,平均批内变异系数为8.13%,交叉反应率均小于0.1%,试剂37℃储存10 d稳定。本方法与市售酶免试剂盒相关性为0.953,阴阳性判断一致,对IMN的检出率为76.9%。结论 采用两步法反应的PLA2R-IgG间接荧光定量免疫层析分析,快速、灵敏、准确,具有临床实用性。  相似文献   

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