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Lateral flow immunoassay (LFIA) is a rapid detection technique that allows researchers to move the antigen-antibody reaction from a test tube or laboratory vessel to a test strip. Due to the chromatographic effect of the test strip, the solution would move to a specified direction based on the test and complete the whole antigen-antibody specific reaction. A qualitative judgment can be made with the naked eye by observing the color change of the reagent strip at a specific location. Because of its advantages of being fast, simple, specific, inexpensive, and requiring no specialized personnel, LFIA is now widely used in medical testing, food quality monitoring, environmental monitoring, agriculture and animal husbandry. A major bottleneck for the development of LFIA technology is the hook effect. This paper summarizes the current methods, means and research progresses to combat the hook effect, hoping to provide a strong technical reference for researchers to design test strips, select suitable nanoparticles, and achieve quantitative LFIA detection.
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Objective:To evaluate the clinical value of NG-Test Carba5 for rapid detection of carbapenemases produced by carbapenem-resistant Enterobacteriaceae (CRE) strains. Methods:A total of 1 210 CRE strains were collected during 2018-2022 from 77 hospitals in 21 provinces of China and were subjected to NG-Test Carba5 for rapid detection of carbapenemase. The whole genome sequencing (WGS) analysis was referenced as the gold standard method.Results:Overall, the NG-Test Carba5 demonstrated excellent performance in detection of five kinds of carbapenemases [Klebsiella pneumoniae carbapenemase (KPC), New Delhi metallo-β-lactamase (NDM), imipenemase metallo-β-lactamase (IMP), Verona integron-encoded metallo-beta-lactamase (VIM) and oxacillinase-48-type carbapenemases(OXA-48)] from CRE strains, with a sensitivity of 98.47% (1 161/1 179), specificity of 100% (31/31), and positive predictive value of 100% (1 161/1 161). The sensitivity for detection of NDM, IMP, OXA and VIM reached 100% (307/307), and 97.70% (763/781) for KPC. For 11 strains carrying blaKPC-25, blaKPC-78, or blaKPC-93, NG-Test Carba5 reported positive KPC detection (11/11). For strains carrying blaKPC-33 and blaKPC-77, however, NG-Test Carba5 delivered negative results. Additionally, for those strains co-producing two or three kinds of carbapenemases, NG-Test Carba5 was able to report all of the targets with a sensitivity of 100% (91/91). Conclusions:NG-Test Carba5 showed excellent performance in rapid and accurate detection of carbapenemases from CRE strains. Nonetheless, for those strains with negative results, some other phenotypic and genotypic methods should be implemented alongside to avoid missing targets.
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Objetivo : Determinar el rendimiento diagnóstico de la técnica de inmnunocromatografía o flujo lateral para la detección de anticuerpos en pacientes con Fasciolosis humana. Materiales y métodos : Estudio observacional, prospectivo y de corte transversal. Hemos desarrollado una prueba de flujo lateral (Fasciorap) para el diagnóstico serológico de las Fasciolosis humana por Fasciola hepatica, compuesta por antígenos de excreción-secreción de formas adultas conjugadas con orocoloidal de 40 nm y una proteína A e IgG de conejo anti Fasciola hepatica como reactivos detectores en la línea de prueba y control, flanqueados por almohadillas en un cassette. Se evaluaron 240 sueros, 120 positivos, 50 sueros de pacientes con otras parasitosis, 20 de pacientes con enfermedades infecciosas y 50 sueros de personas no parasitadas, la interpretación de resultados se realizó por inspección visual a los 15 minutos de aplicada las muestras. Resultados : La prueba detectó la presencia de anticuerpos en el suero de pacientes con fasciolosis, alcanzando una sensibilidad de 92,5%, una especificidad de 94,17%, un valor predictivo positivo de 94,07% y negativo de 92,62%; con 100% de concordancia en la repetibilidad y reproducibilidad. Conclusiones : Fasciorap detecta casos de fasciolosis, por lo tanto, es una potencial prueba diagnóstica en zonas endémicas donde se requiere pruebas de punto de atención
Objective : To determine the diagnostic performance of the immunochromatography technique or lateral flow for the detection of antibodies in patients with human fasciolosis. Materials and methods : Observational, prospective and cross-sectional study. We have developed a lateral flow test (Fasciorap) for the serological diagnosis of fasciolosis due to F. hepatica, composed of excretion-secretion antigens of adult forms conjugated with orocolloid of 40 nm and a protein A and IgG of rabbit anti F. hepatica as detector reagents in the test and control line, flanked by pads in a cassette. 240 sera were evaluated, 120 positive, 50 sera from patients with other parasites, 20 from patients with infectious diseases and 50 sera from non-parasitized people, the interpretation of results was performed by visual inspection 15 minutes after applying the samples. Results : The test detected the presence of antibodies in the serum of patients with fasciolosis, reaching a sensitivity of 92.5%, a specificity of 94.17%, a positive predictive value of 94.07% and a negative predictive value of 92.62%; with 100% agreement on repeatability and reproducibility. Conclusions : Fasciorap detects cases of fascioliasis, therefore, it is a potential diagnostic test in endemic areas where point-of-care testing is required
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Objective@#To establish a colloidal gold technique assay for the rapid detection of immunoglobulin(Ig) M and IgG antibodies against 2019 novel coronavirus (2019-nCoV) and to evaluate its clinical performance.@*Methods@#A total of 278 patients who were treated at Wuhan Hankou Hospital and the People's Hospital of Honghu from February 12, 2020 to February 20, 2020 were collected. According to the diagnostic criteria, 89 patients were confirmed with 2019-nCoV nucleic acid positive diagnosis, and 189 were 2019-nCoV nucleic acid-negative suspected patients. A total of 273 medical examiners from Nanfang Hospital, Southern Medical University from 2015 to 2018 were selected as controls. The serum samples of patients were collected. 2019-nCoV nucleic proteins were obtained from prokaryotic expression vectors. Indirect IgM and IgG colloidal gold techniques were established by using recombinant N protein. 2019-nCoV nucleic acid detection by reverse transcription-polymerase chain reaction (RT-PCR) was used as control. Serum specimens were tested for 2019-nCoV IgM and IgG. The specificity and sensitivity of colloidal gold assay were analyzed.@*Results@#The sensitivity and specificity of IgM detection reagents were 78.7% and 98.2%, respectively, those of IgG detection reagents were 73.0% and 99.3%, respectively, and those of IgM combined with IgG detection were 87.6% and 98.2%, respectively. For suspected patients with negative 2019-nCoV nucleic acid, the positive rates of IgM and IgG were 59.8% (113/189) and 52.9% (100/189), respectively, and the positive rate of IgM combined with IgG detection was 66.1% (125/189).@*Conclusion@#This reagent of 2019-nCoV antibodies detection (colloidal gold technique) fulfills the requirement for clinical application with high specificity and sensitivity, which can be served as a supplementary detection method for 2019-nCoV nucleic acid detection by RT-PCR.
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Objective@#To establish the method of colloidal gold immunochrom atographic assay for detecting cadmium ions rapidly.@*Methods@#The anti-cadmium ion monoclonal antibody-gold conjugate was labeled on the binding pad, cadmium ion hapten and goat anti-mouse IgG were coated on nitrocellulose membrane as the detection line (T line) and quality control line (C line) respectively. The sample pad, colloidal gold bonding pad, nitrocellulose membrane and absorption pad were orderly assembled on the PVC board to cut into a test paper strip. The qualitative results of the assay were visualized in color.@*Results@#When detecting the human urine cadmium ions, the results were tested qualitativly within 15 minutes. The detection limit was 30 μg/L. No cross-reactivity with other heavy metal ions. The test paper strip could be stored at 4 ℃ for 3 months.@*Conclusion@#The method has the advantages of low cost, strong specificity, good stability and reliable results, and is suitable for rapid screening of cadmium poisoning of enterprise and occupational health.
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Objective To assess the limit of detection(LOD),sensitivity and specificity of collodial gold immunochrom-atography(GICA)products purchased from two manufacturers under special environmental conditions.Methods The sensitivity and specificity of GICA made in InTec Products, INC.and Beijing WANTAI Biological Pharmacy Enterprise Co., LTD.for detecting HBsAg, anti-HCV and anti-Treponema pallidum(TP)serum samples were evaluated under different conditions(conventional facilities,simulated hot and humid environments and simulated low pressure and hypoxia environments)according to the protocol of kits.LOD was estimated by detecting the standard materials obtained from the National Center for Clinical Laboratory(NCCL)of China.Results LOD for syphilis improved from 2 NCU to 1 NCU using GICA from InTec Products in hot and humid environments.The extreme conditions did not influence the specificity of GICA from the two manufacturers in the course of detection of clinical samples,but the sensitivity of detection was affected.For InTec Products,the sensitivity of hepatitis B virus and syphilis detection was improved in hot and humid environments,but was reduced in low pressure and hypoxia environments.In addition,the sensitivity of hepatitis C virus detection by InTec Products decreased in hot and humid environments.As for WANTAI products,the sensitivity of hepatitis B virus detection was reduced under extreme conditions and that of hepatitis C virus was only influenced by hot and humid environments. Interestingly, extreme conditions had no impact on the sensitivity of syphilis.Conclusion LOD of InTec Products is better than that of the WANTAI products for detection of standard materials from blood-borne diseases.In the process of detecting clinical samples,the sensitivity of the two manufacturers′GICA is influenced by extreme conditions, with the specificity unchanged.Overall, WANTAI products are more stable than those of InTec, and are also less influenced by extreme conditions.
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Objective The purpose of this study was to assess the analysis capabilities of the dot immunogold filtration method on detecting serum amyloid A ( SAA ) protein in blood.It also aimed to research the clinical value of SAA in diagnosing the infectious diseases of children .Methods ( 1 ) The performance evaluation including the accuracy , within-run precision, inter assay variations , the linear and the distraction-analysis of SAA-SPOT was estimated following the EP file; From March to July in 2014, children from five 3A Grade hospitals in Guangdong Province were enrolled into this observational study.Data including white blood WBC count , CRP and SAA were obtained.(2) From March to July in 2014, children from five 3A Grade hospitals in Guangdong Province were enrolled randomly into this observational study.This study used a cross-sectional survey research method , and 386 children with bacterial infection and 219 children with virus infection were as the research object.The general , clinical diagnosis , treatment information as well as the data of blood SAA , C-reactive protein ( CRP ) and white blood cell ( WBC ) of children were collected.Data were analyzed by variance , independent t test, ROC curve analysis and stepwise regression statistics method.Results ( 1 ) The average recovery rate is 103.74 %.Coefficient of variation (CV) for 10 mg/L,100 mg/L within-run assays were 8.77%, 3.61% and between-run assays were 9.01%, 3.74%;the inter-day CV were 9.07%, 4.03%respectively;the linear range was 5 mg/L-200 mg/L, hemoglobin(5 g/L),serum bilirubin(800 μmol/L),triglyceride(TG, 22 mmol/L), and had no interference in SAA detection.When compared to the BNPRO quantitate system of SIEMENS , the coefficient of association of detection of SAA by SAA-SPOT was R2 =0.96.( 2 ) Compared with control group , the serum SAA of infection group ( bacterial infection group , t =13.05, P=0.001;virus infection group t =7.68, P=0.001) and SAA/CRP ratio (bacterial infection group t=2.29, P=0.023;virus infection group t=3.32, P=0.01) were significantly increased.(3) The serum CRP and SAA rose similarly in bacterial infection, while in viral infection, only SAA increased significantly , CRP had no apparent change.In combination with CRP and WBC , SAA had the better diagnostic efficiency apparently.Conclusions As a POCT detection project , analysis capabilities of the SAA assayed by domestic SAA-SPOT can meet the requirements of clinical test.Combined with CRP , WBC and SAA can improve the efficiency in the diagnosing of infectious disease especially in the virus infection.As a new biomarker of infections , SAA is useful for the early auxiliary diagnosis and differential diagnosis of childhood infection.
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As a weapon of mass destruction ,the biological weapon , composed of biological warfare agents and their re-lease devices,is characterized by strong pathogenicity , large pollution areas, various routes of infection, low cost, user-friendliness and a large number of impact factors .Although the United Nations has banned the use of biological weapons , there are still some countries and regions that continue biological weapon researches .In addition, illegal use of biological warfare agents in the field of terrorism and non-military arena poses a serious threat to public safety .Early detection of bio-logical warfare agent use and determination of its type are crucial to biological weapon defense and epidemic control .There-fore, to enhance researches on rapid detection and early warning of biological warfare agents is of great significance .This paper reviews the main technologies currently applied to the field of biological warfare agent detection and their progress .
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Objective To study the sensitivity and specificity of gold-immunochromatography assay (GICA) for detection of Yersiniapestis(Y. pestis ) F1 antigen. Methods Viscera organ(liver and spleen) specimens of 308 mice with virulent Y. pestis infection and 225 control specimens of rats(217 Spermophilus dauricus, 5 mice,3 guinea pigs) were detected by GICA dipstick with monoclonal antibody against plague F1 antigen (F1MAb).Meanwhile, micro-method of reverse indirect hemagglutination assay(RIHA) and bacteria culture were carried out for parallel testing. Results Bacteriological examination of 225 control specimens, and F1 antigen detected with GICA and RIHA were all negative. No cross-reaction with related Yersinia pseudotuberculosis at 1 x 108 cfu/ml level was found in GICA and RIHA. Detection sensitivity of Y. pestis by GICA and RIHA were 2.5 × 105 cfu/ml and 2.0 × 105 cfu/ml, respectively, and of F1 antigen were 1μg/L and 10 μg/L, respectively. Coincidence was 97.94% (522/533) between GICA and bacteriological test, Kappa = 0.959, and the difference was statistically insignificant(x2 = 0.36, P ＞ 0.05); and 97.94%(522/533) between GICA and RIHA, Kappa = 0.959, with statistically significant difference in the positive detection rates(x2 = 9.09, P ＜ 0.05). Out of the 308 infected mice, 284 were positive of plague bacterial cultured, In 284 samples with positive bacterial culture, there were 280 of positive detected by GICA for F1 antigen, positive rate of F1 antigen was 98.59%, higher than that by RIHA[the positive rate of 96.13%(522/533)], with statistically significant difference(x2 = 5.14, P ＜ 0.05). Sensitivity of GICA was 98.59% (280/284), specificity was 97.19% (242/249), positive predictive value (PPV) was 97.56% (280/287),negative predictive value ( NPV ) was 98.37% (242/246), and Youden index was 0.9578. Conclusions GICA is sensitive and specific, fast and simple in detection of F1 antigen of the plague. It's a valuable detection technique for early and rapid diagnosis of plague.
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Objective To establish hybridization method by using the DNA-modified colloid gold nanopartieles probes for rapid and specified detection of methicillin resistant Staphylococcus aureus (MRSA). Methods DNA-modified nanoparticles probes were prepared by using two mereapto-modified mecA gene-specific oligonucleotide probes bounding with 6Ohm-diameter colloid gold nanoparticles through covalent binding. Genomic DNA of Staphylococcus aureus strains were extracted and then fragmented by ultrasonic waves. The fragmentized DNA was hybridized with the DNA-modified colloid gold nanoparticles probes. The reaction products were centrifuged and then detected by reversed-phase thinlayer chromatography plate to observe any colloid gold nanoparticles precipitation. The results of mecA gene detected by the colloid gold nanoparticles probes hybridization were compared with the results of PCR and the accuracy of the hybridization method was evaluated. Results Of total 95 tested strains, 71 strains were confirmed as MRSA and 24 swains were confirmed as methicillin susceptible Staphylococcus aureus (MSSA) by PCR. Of 71 MRSA strains, 69 strains were positive by colloid gold nanoparticles probes hybridization, the sensitivity of this method was 97.2%. All of the 24 MSSA strains were negative by using this technique. The specificity of this method was 100%. Of total 95 test strains ,93 strains were detected correctly. The accuracy was 97.9%. Conclusions Colloid gold nanoparticles probes hybridization test is well consistent with the gold standard method of PCR in detection of MRSA. Detection of MRSA by using the technique of the DNA-modified colloid gold nanopartichs probes hybridization is rapid, simple and accurate. It is potent to be a new method for rapid diagnosis of MRSA infection.
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Objective To develop a rapid test for the detection of F1 antigen of Yersinia Pestis based on gold-immunochromatography.Methods F1 antibodies were coupled with colloidal gold to prepare collidal gold reagent,which was used to detect F1 antibodies based on double antigen sandwich.The collidal gold reagent was estimated for its sensitivity specificity and stablity in labs and 1798 samples were detected in 17 surveillance spots.Results The reagent was sensitive to 0.0010 g/L F1 antigens.The reagens kept stable when it had been placed at 4℃ or room-temperature for 12 months and did not react to Yersinia pseudotuberculosis and Yersinia enterolitica.In 17 surveillance labs the reagent was used to test 1798 viscera samples from animal.resulting an accordance rate of 97.11%(1746/1798)to bacterial culture and 96.83%(1741/1798)accordance to reverse indirect hemagglutination assay(RIHA),showing a higher detection rate[9.23%(166/1798)]compared with RIHA[6.79%(122/1798)]and bacterial culture[6.28%(113/1798)].Conclusions The collidal gold reagent,sensitive and specific in diagnosing Yersinia pestis infection of both human and animals,is a rapid method in surveillance spot.
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Objective To establish an early,simple and rapid colloidal gold strip method for the detection of IgM against hantavirus nucleocapsid protein in patients with hemorrhagic fever with renal syndrome(HFRS).Methods Purified recombinant Hantavirus nucleoprotein(rNP)was labeled by colloidal gold particles and then sprayed and fixed on fiberglass membrane as the combination pad.Anti-Human IgM(μ-chain specific)antibody produced in goat was fixed in the detection area,and mouse antihantavirus antibody was fixed in the quality control area.Both of them were on nitrocellous membrane strip in tandem.Together with a specimen pad ahead.The conbination pad and the nitrocellous membrane were assembled into a test strip.The colloidal gold strip assay was compared with ELISA for evaluation of specificity and sensitivity.Results The colloidal gold strip tests showed positive in the serum samples from 50 cases of HFRS which was clinically diagnosed and then verified by ELISA within 10-15 minutes.Whereas 30 serum samples of healthy donors have tested negative.Conclusions Our new colloidal gold immunochromatographic test strip method was well concordant with the ELISA assay,but the former was more raoid and simole.It could be used primary medical services.
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Objective To evaluate the sensitivity and speciality of protein chip technology, and discuss its value in diagnosis or classification of autoimmune diseases, and to make its methodological evaluation. Methods The anti-dsDNA was detected with gold-colloid assay, indirect immunoflurescence(IIF) assay and protein chip technology, respectively; the other seven autoantibodies including anti-SSA, anti-SSB, anti-Sm, anti-u1RNP, anti-Rib-P, anti-Scl-70 and anti-Jo-1 were simultaneously detected with immunoblotting(IBT) assay and protein chip technology, and then all the results were delt with statistical method. Results For anti-dsDNA, the sensitivity of protein chip technology was better than that of gold-colloid assay; there was significant difference between protein chip technology and IBT assay in detecting anti-Jo-1 in DM/PM(P