Dual-color immunochromatographic test strip for simultaneous sensitive detection of malachite green and leucomalachite green residues in fish and shrimp meat samples.

A sensitive dual immunochromatographic test strip (dual-ICTS) was developed to detect malachite green (MG) and its metabolite, leucomalachite green (LMG), using two types of gold nanoparticles: round-shaped (red) and star-shaped (blue). The detection limits were determined to be 0.221 µg L-1 for MG and 0.214 µg L-1 for LMG, respectively. The dual-ICTS provided a cut-off value of 1.8 µg L-1 for MG and LMG detection. The dual-ICTS successfully detected MG and LMG in food samples, with recovery rates ranging from 86 % to 116 %. The dual-ICTS was evaluated by correlation analysis between the proposed assay and the well-established enzyme-linked immunosorbent assay in the MG and LMG detection. This is the first report on the development of the ICTS that can detect both MG and LMG at the same time within only 5 min, making it a sensitive and rapid tool for on-site detection.

A novel peptide pair-based rapid fluorescent diagnostic system for malaria Plasmodium falciparum detection.

Advanced diagnostic materials, such as aptamers, are required due to the scarcity of efficient diagnostic antibodies and the low sensitivity of rapid diagnostic kits at detecting the malaria parasite, Plasmodium falciparum. METHODS: Two peptides M2.9 [(KPTAEQTESPELQSAPEN) and M2.17 (KILFNVYSPLGCTCECWV)] were designed using simple epitope prediction tools and modified against the merozoite surface antigen 2 of P. falciparum (Pf.MSP2) by 3-dimensional modeling based on binding affinity. Based on five prediction tools for hydropathy, M2.17 was selected as an appropriate capture peptide. A peptide-based fluorescence-linked immunosorbent assay (FLISA) and a peptide pair-based fluorescent immunochromatographic test strip (FICT) were developed to detect P. falciparum 3D7 (drug-sensitive) and P. falciparum K1 (multi drugs-resistant) strains. RESULTS: Bioinformatic analysis of two peptides demonstrated the potential binding affinity with the merozoite surface protein 2 of P. falciparum (Pf.MSP2) with a positive hydropathy value. The limit of detection (LOD) of FLISA was 10 parasites/µL and of a peptide pair-linked rapid FICT system was 5 and 200 parasites/µL for P. falciparum 3D7 and K1, respectively. Compared to commercial rapid detection systems (RDTs), a peptide pair-linked FICT system exhibited a 20-fold greater efficiency in detecting P. falciparum 3D7 and specifically discriminated another protozoan spp. CONCLUSION: A peptide pair-linked rapid diagnostic strip could be an alternative to conventional RDTs for monitoring wild-type and drug-resistant malaria parasites.

Multifunctional Fe3O4@CuS nanoparticle-driven colorimetric and photothermal immunochromatographic test strip for the sensitive detection of Salmonella typhimurium in milk.

Magnetic nanoparticles are widely employed as signal labeling reporters in immunochromatographic test strips (ICTS) for detecting foodborne pathogens due to their outstanding anti-interference and magnetic enrichment performance. However, the insufficient colorimetric signal brightness of magnetic nanoparticles results in poor sensitivity, hindering their ability to meet the growing demand for advanced ICTS. Herein, we synthesized Fe3O4@CuS core-shell structure nanoparticles using a facile in-situ growth method. These Fe3O4@CuS nanoparticles exhibit a superior photothermal conversion efficiency of 42.12 % and a magnetization strength of 35 emu/g. We developed a dual-readout format ICTS based on Fe3O4@CuS, incorporating both colorimetric and photothermal formats to enhance sensitivity for Salmonella typhimurium detection. The limit of detection for Fe3O4@CuS-ICTS in the colorimetric and photothermal format was 5 × 104 CFU/mL and 7.7 × 10³ CFU/mL, respectively. Additionally, the average recoveries ranged from 91.25 % to 103.39 %, with variations from 2.2 % to 11.1 %, demonstrating good accuracy and precision. Therefore, this work suggests that Fe3O4@CuS nanoparticles, with their superior magnetic, optical, and photothermal properties, can serve as promising signal labeling reporters to improve the detection performance of ICTS and hold potential for constructing more accurate and sensitive point-of-care testing platforms.

Development and Validation of a Novel Multiplex Real-Time PCR Assay for Rapid Detection of Carbapenemase Genes in Carbapenem-Resistant Enterobacterales Isolates and Clinical Samples.

Purpose: Carbapenem-resistant Enterobacterales (CRE) infection is an urgent threat to human health. This study aimed to develop and validate a novel multiplex real-time PCR (multi-qPCR) assay for the detection of the blaKPC, blaNDM, blaIMP, blaOXA-48-like, and blaVIM genes in CRE isolates and clinical samples, as well as to compare it with three phenotypic methods. Methods: The reliability and limit of detection (LOD) of the multi-qPCR assay were evaluated. PCR and DNA sequencing were used as the reference methods to identify carbapenemase genes in CRE isolates and clinical samples. The accuracy of the multi-qPCR assay, modified carbapenem inactivation and EDTA-modified carbapenem inactivation method (mCIMandeCIM), carbapenemase inhibitor-based combined disk test (CDT), and colloidal gold-based immunochromatographic test was compared with the reference methods with 182 isolates of CRE. Furthermore, 112 clinical samples were collected to validate the efficacy of this multi-qPCR assay. Results: The standard deviations (CVs) of intra-assay and inter-assay of the multi-qPCR assay were ≤ 0.53% and ≤ 2.04% for detecting the five major carbapenemase genes, respectively; while the LOD ranged from 2×102 copies/mL to 8×102 copies/mL. PCR and DNA sequencing confirmed 168 out of 182 CRE isolates producing carbapenemase(s): KPC (n = 93), NDM (n = 46), IMP (n = 8), OXA-48-like (n = 14), VIM (n = 1), KPC&NDM (n = 5), and KPC&NDM&IMP (n = 1). The accuracy of mCIMandeCIM, CDT, Colloidal Gold, and the multi-qPCR assay was 96.2%, 89.6%, 100%, and 100% respectively for detecting carbapenemase(s) producers. Moreover, the sensitivity and specificity of the multi-qPCR assay were all 100% for the detection of each carbapenemase gene in clinical samples, compared with PCR and sequencing. Conclusion: For clinical isolate detection, the multi-qPCR assay is comparable to Colloidal Gold, and superior to mCIMandeCIM and CDT; while for clinical samples detection, it also shows excellent performance. Therefore, the multi-qPCR assay has great potential for clinical diagnosis.

Visual Loop-Mediated Isothermal Amplification (LAMP) Assay for Rapid On-Site Detection of Escherichia coli O157: H7 in Milk Products.

(1) Background: Rapid on-site testing is an effective method for the detection of Escherichia coli O157: H7(E. coli O157: H7) in food ingredients and the environment. (2) Methods: In this study, we developed colorimetric loop-mediated isothermal amplification (LAMP) and immunochromatographic test strips (ICTs) for the rapid and visual detection of E. coli O157: H7. This study designed new specific LAMP primers for E. coli O157: H7 virulence island genes. After the LAMP amplification, the double-stranded DNA target sequence labeled with digoxin and fluorescein isothiocyanate (FITC) at both ends was bound to the anti-digoxin antibody on the gold nanoparticles. Subsequently, it was further bound to the anti-FITC antibody at the T line of the ICTs, forming a positive test result. Hydroxynaphthyl blue dye was directly added to the LAMP amplification product. A blue color indicated positive results, while a purple color indicated negative results. (3) Results: Two visualization methods showed high specificity for the target strains. The visualization tests had sensitivities of 5.7 CFU mL-1, and the detection limit of the Escherichia coli O157: H7 in artificially contaminated milk samples was 5.7 × 102 CFU mL-1, which was consistent with the results of the standard method (LAMP-electrophoresis method) used in commercial inspection. (4) Conclusions: Both methods could be useful in remote and under-resourced areas.

An Immunochromatographic Test Strip for Rapid Quantitative Control of Monoclonal Antibodies against Programmed Cell Death Protein 1.

Cancer is one of the major public health challenges in the world, which is characterized by rapid progression and high mortality. Immunotherapy, represented by PD-1 monoclonal antibody, has significantly improved the efficacy of malignant tumors and has become one of the most popular immunotherapy methods at present. Therefore, there is an increasing demand for novel detection methods for PD-1 monoclonal antibodies. The aim of this work was to establish a rapid, simple, and sensitive immunochromatographic test strip (ICTS) based on the AuNPs enlargement for both visual and instrumental detection of the PD-1 monoclonal antibody concentration. The mixed solution of NH2OH·HCl and HAuCl4 was used as an enhancement solution to lower the detection limit and achieve higher sensitivity. A test strip reader was used to construct a visualized quantitative detection standard curve for the PD-1 monoclonal antibody concentration. The LOD was 1.58 ng/mL through a triple signal-to-noise ratio. The detection time was within 10 min. The constructed test strips can rapidly, accurately, and efficiently detect the concentration of PD-1 monoclonal antibody in real samples.

Identification of novel biomarkers for anti-Toxoplasma gondii IgM detection and the potential application in rapid diagnostic fluorescent tests.

Toxoplasmosis, while often asymptomatic and prevalent as a foodborne disease, poses a considerable mortality risk for immunocompromised individuals during pregnancy. Point-of-care serological tests that detect specific IgG and IgM in patient sera are critical for disease management under limited resources. Despite many efforts to replace the T. gondii total lysate antigens (TLAs) by recombinant antigens (rAgs) in commercial kits, while IgG detection provides significant specificity and sensitivity, IgM detection remains comparatively low in sensitivity. In this study, we attempted to identify novel antigens targeting IgM in early infection, thereby establishing an IgM on-site detection kit. Using two-dimensional gel electrophoresis (2DE) and mouse serum immunoblotting, three novel antigens, including EF1γ, PGKI, and GAP50, were indicated to target T. gondii IgM. However, rAg EF1γ was undetectable by IgM of mice sera in Western blotting verification experiments, and ELISA coated with PGKI did not eliminate cross-reactivity, in contrast to GAP50. Subsequently, the lateral flow reaction employing a strip coated with 0.3 mg/mL purified rAg GAP50 and exhibited remarkable sensitivity compared with the conventional ELISA based on tachyzoite TLA, which successfully identified IgM in mouse sera infected with tachyzoites, ranging from 103 to 104 at 5 dpi and 104 at 7 dpi, respectively. Furthermore, by using standard T. gondii-infected human sera from WHO, the limit of detection (LOD) for the rapid fluorescence immunochromatographic test (FICT) using GAP50 was observed at 0.65 IU (international unit). These findings underline the particular immunoreactivity of GAP50, suggesting its potential as a specific biomarker for increasing the sensitivity of the FICT in IgM detection.

Preparation of Hybrid Magnetic Nanoparticles for Sensitive and Rapid Detection of Phorate Residue in Celery Using SERS Immunochromatography Assay.

Extensive use of pesticides in agricultural production has been causing serious health threats to humans and animals. Among them, phorate is a highly toxic organophosphorus insecticide that has been widely used in planting. Due to its harmful effects on human and animal health, it has been restricted for use in many countries. Analytical methods for the rapid and sensitive detection of phorate residues in agricultural products are urgently needed. In this study, a new method was developed by combining surface-enhanced Raman spectroscopy (SERS) and immunochromatography assay (ICA). Hybrid magnetic Fe3O4@Au@DTNB-Ab nanoprobes were prepared by modifying and growing Au nanoseeds on an Fe3O4 core. SERS activity of the nanoprobe was optimized by adjusting the concentration of the Au precursor. A rapid and sensitive assay was established by replacing the traditional colloidal gold-based ICA with hybrid SERS nanoprobes for SERS-ICA. After optimizing parameters including coating antibody concentrations and the composition and pH of the buffer solution, the limit of detection (LOD) for phorate could reach 1 ng/mL, with a linear range of 5~100 ng/mL. This LOD is remarkably lower than the maximum residue limit in vegetables and fruits set by the Chinese government. The feasibility of this method was further examined by conducting a spiking test with celery as the real sample. The result demonstrated that this method could serve as a promising platform for rapid and sensitive detection of phorate in agricultural products.

Evaluation of the diagnostic performance of an immunochromatographic test for Chlamydia trachomatis.

Objectives: To evaluate the diagnostic performance of different brands of immunochromatographic test (ICT) reagents for Chlamydia trachomatis using homogenized samples to provide a reference for reagent quality control. Methods: Eight commercially available ICT reagents were evaluated, of which three used the latex method and five used the colloidal gold method. Analytical performance evaluation using a pure culture broth of C. trachomatis, as well as clinical application validation using cervical epithelial cell samples acquired from the research subjects, were conducted. The concentration of C. trachomatis was quantified using a nucleic acid amplification test. Results: The limit of detection (LOD) of different ICT reagents in the analytical performance evaluation varied from 9.5 × 103 to 1 × 105 IFU/mL, and only one reagent met the LOD specified in the manufacturer's instructions. Likewise, only one reagent in the clinical application validation achieved the analytical LOD, four reagents were 2.1-4.2-fold of the analytical LODs, and three reagents failed to detect positive results in clinical samples. Conclusions: The diagnostic performance of different methods and different brands of ICT reagents in clinical practice was different from the manufacturer's instructions and the results of laboratory evaluation. The diagnostic performance of reagents should be evaluated before they are actually used in clinical practice.

High prevalence of anti-Strongyloides antibody in SARS-CoV-2-infected human sera in a Thai hospital: Rapid serological screening.

COVID-19, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), can stimulate a systemic inflammatory response with severe lung involvement, multisystem dysfunction, and death in some cases. Immunosuppressive treatments have been proposed for management of COVID-19 patients, but these bring the risk of flare-up of pre-existing infections. Strongyloidiasis can become severe or fatal in immunocompromised individuals. This cross-sectional study determined the prevalence of anti-Strongyloides IgG antibody in sera collected from SARS-CoV-2 infected persons in a tertiary-care Thai hospital from January 2021 to January 2022. The survey was conducted using a rapid immunochromatographic test (ICT) kit based on a recombinant antigen of Strongyloides stercoralis known to be IgG-immunoreactive. High prevalence of anti-Strongyloides IgG antibody was found. Out of 297 SARS-CoV-2-infected patients 117 (39.4 %, 95 % CI 33.8-45.2 %) were positive for S. stercoralis according to the ICT kit. In areas where strongyloidiasis is endemic, we suggest using this point-of-care ICT kit for routine rapid screening in seriously ill COVID-19 patients who will be subjected to immunosuppressive treatment. Prompt anthelminthic treatment should be administered to prevent serious systemic strongyloidiasis in at-risk patients.

Computerized analysis of haptens for the ultrasensitive and specific detection of Pyriftalid.

Pyriftalid (Pyr) is one of the most commonly used herbicides and due to its widespread and improper use, it has led to serious pollution of groundwater, soil and other ecosystems, threatening human health. A rapid method to detect Pyr was urgently needed. A high specific monoclonal antibody (mAb) against Pyr with IC50 values of 4.7 ng/mL was obtained by mAb screening technique and method with enhanced matrix effect. The study firstly proposed colloidal gold immunochromatographic test strips (CGIA) for Pyr, which enables rapid qualitative and quantitative determination of a large number of samples anytime and anywhere, so as to effectively monitor Pyr in environment and grain samples. Based on the properties of the desired Pyr antibody, the hapten Pyr-hapten-4 with high structural similarity to Pyr molecule, similar electrostatic potential distribution, and the ability to expose Pyr functional groups was screened out from five different Pyr haptens, which was consistent with mouse antiserum test. The CGIA quickly analyze the Pyr content in positive samples such as water samples, soil samples, paddy samples, brown rice samples within 10 min, the LOD for Pyr by CGIA as low as 1.84 ng/g, the v LOD value as low as 6 ng/g, and the extinction value as low as 25 ng/g. The content of positive samples detected by CGIA was consistent with the quantitative results of LC-MS/MS, the relative accuracy was within the range of 97-103 %. The recovery rate range for Pyr by CGIA was 92.0-99.7 %, and the coefficient of variation was between 1.30-8.56 %. It indicated Pyr-targeted CGIA test strip was an efficient and fast detection method to detect real environment and food samples.

A rapid simultaneous antigen detection of Haemophilus influenzae and Streptococcus pneumoniae for predicting the prognosis of acute otitis media.

BACKGROUND: Rapid identification of causative bacteria in treatment of acute otitis media (AOM) is of paramount importance for appropriate antibiotic use. MATERIALS AND METHODS: This prospective observational study was conducted in 15 hospitals and clinics in Japan between 2018 and 2020. A new rapid antigen test kit (AOS-116), which simultaneously detects antigens for Streptococcus pneumoniae (Sp) and Haemophilus influenzae (Hi), was applied for middle ear fluids (MEFs) and nasopharyngeal secretions (NPSs) in patients with moderate to severe AOM. We investigated relationship between the results of rapid test, severity at initial visit, and clinical course. RESULTS: Regarding performance accuracy based on culture results, AOS-116 showed 1) high (>80%) sensitivity, specificity, and negative predictive value (NPV) in MEFs for both antigens, 2) high sensitivity, specificity, and positive predictive value (PPV) in NPSs for Hi antigen, and 3) high specificity, and PPV in NPSs for Sp antigen. Regarding predictive value of nasopharyngeal culture and antigen detection for causative middle ear pathogens, similar results were observed between AOS-116 and culture, which was characterized with high sensitivity and NPV for both pathogens. MEFs/NPSs positive for Hi antigen were significantly associated with eardrum findings, and severity. MEFs/NPSs positive for pneumococcal antigen were significantly associated with severity of otalgia, fever, and otorrhea. Among patients with prior antimicrobial treatment, improvement tended to be slower in cases positive for Hi than in cases negative. CONCLUSION: The rapid antigen detection test is useful as a decision-making tool for prescribing antimicrobial agents and may play an important role in promoting appropriate antimicrobial use.

Development of a dual immunochromatographic test strip to detect E2 and Erns antibodies against classical swine fever.

Background: It is essential to consider a practical antibody test to successfully implement marker vaccines and validate vaccination efficacy against classical swine fever virus (CSFV). The test should include a serological antibody assay, combined with a tool for differentiating infected from vaccinated animals (DIVA). The immunochromatographic test strip (ICS) has been exclusively designed for detecting CSFV E2 antibodies while lacking in detecting Erns antibodies, which can be employed and satisfy DIVA strategy. This study developed a novel ICS for detecting CSFV E2/Erns dual-antibody. The effectiveness of ICS in evaluating the DIVA capability of two novel chimeric pestivirus vaccine candidates was assessed. Methods: Recombinant E2 or Erns protein was transiently expressed in the plant benthamiana using Agrobacterium tumefaciens. ICS was subsequently assembled, and goat anti-rabbit IgG and recombinant CSFV E2 or Erns protein were plated onto the nitrocellulose membrane as control and test lines, respectively. The sensitivity and specificity of ICS were evaluated using sera with different neutralizing antibody titers or positive for antibodies against CSFV and other pestiviruses. The coincidence rates for detecting E2 and Erns antibodies between ICS and commercial enzyme-linked immunosorbent assay (ELISA) kits were also computed. ICS performance for DIVA capability was evaluated using sera from pigs vaccinated with conventional vaccine or chimeric vaccine candidates. Results: E2 and Erns proteins were successfully expressed in N. benthamiana-produced recombinant proteins. ICS demonstrated high sensitivity in identifying CSFV E2 and Erns antibodies, even at the low neutralizing antibody titers. No cross-reactivity with antibodies from other pestiviruses was confirmed using ICS. There were high agreement rates of 93.0 and 96.5% between ICS and two commercial ELISA kits for E2 antibody testing. ICS also achieved strong coincidence rates of 92.9 and 89.3% with two ELISA kits for Erns antibody detection. ICS confirmed the absence of CSFV Erns-specific antibodies in sera from pigs vaccinated with chimeric vaccine candidates. Conclusion: E2 and Erns proteins derived from the plant showed great potential and can be used to engineer a CSFV E2/Erns dual-antibody ICS. The ICS was also highly sensitive and specific for detecting CSFV E2 and Erns antibodies. Significantly, ICS can fulfill the DIVA concept by incorporating chimeric vaccine candidates.

Assessment of Blood and Semen Detection and DNA Collection from Swabs up to Three Months after Deposition on Five Different Cloth Materials.

Body fluid identification plays a crucial role in criminal investigations. Because of their presence in many cases, blood and semen are the most relevant body fluids in forensic sciences. Based on antigen-antibody reactions binding unique proteins for each body fluid, serological assays represent one of the most rapid and highly specific tests for blood and semen. Currently, few studies have assessed the factors affecting body fluid identification by applying these assays. This work aimed to study the effect of different fabrics from clothes and time since deposition on identification through immunochromatographic tests for blood and semen, DNA isolation, and STR profiling from these samples. Body fluids were deposited on black- and white-dyed denim and cotton fabrics, and on leather. Afterward, blood and semen were sampled at 1 day, 30 days, and 90 days after deposition and identified by using the SERATEC® HemDirect Hemoglobin Test and the PSA Semiquant and SERATEC® BLOOD CS and SEMEN CS tests, respectively. Laboratory and crime scene tests presented similar performances for the detection of blood and semen stains on every tested fabric. No differences were found on band intensities between timepoints for all fabrics. It was possible to recover and identify blood and semen samples up to three months after deposition and to obtain full STR profiles from all the tested fabrics. Both body fluid STR profiles showed differences in their quality between 1 and 90 days after deposition for all fabrics except for black cotton for semen samples. Future research will expand the results, assessing body fluid identification on other substrates and under different environmental conditions.

Diagnostic performance of a rapid immunochromatographic test for the simultaneous detection of antibodies to Theileria equi and Babesia caballi in horses and donkeys.

BACKGROUND: Equine piroplasmosis is caused by two tick-borne protozoan parasites, Theileria equi and Babesia caballi,, which are clinically relevant in susceptible horses, donkeys, and mules. Moreover, equine piroplasmosis significantly constrains international trading and equestrian events. Rapidly diagnosing both parasites in carrier animals is essential for implementing effective control measures. Here, a rapid immunochromatographic test for the simultaneous detection of antibodies to T. equi and B. caballi was evaluated using samples from horses and donkeys collected in Greece, Israel, and Italy. The results were compared with an improved competitive enzyme-linked immunosorbent assay (cELISA) for detecting antibodies to both parasites using the same panel of samples. METHODS: Blood samples were collected from 255 horses and donkeys. The panel consisted of 129 horses sampled at four locations in northern Greece, 105 donkeys sampled at four locations in Sicily, and 21 horses sampled at two locations in Israel. The rapid test and the cELISA were performed according to the manufacturer's instructions, and the results were subjected to a statistical analysis to determine the sensitivity and specificity of both tests and their association. RESULTS: The immunochromatographic test provided a result within 15 min and can be performed in the field, detecting both pathogens simultaneously. The overall coincidence rate between the rapid test and the cELISA for detecting antibodies against T. equi was 93% and 92.9% for B. caballi. The rapid test's sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for T. equi were above 91.5%. Sixteen samples were positive for both parasites in the rapid test and eight in the cELISA. Either test had no significant association between T. equi and B. caballi detection. The detection rates of both parasites were significantly higher in Italy than in Greece or Israel and in donkeys than in horses. The agreement for T. equi between the results of both tests was high in Greece (93.8%) and Italy (95.2%) and moderate in Israel (76.2%). For B. caballi, the specificity and NPV of the rapid test were high (94.2% and 98.3%, respectively), although the sensitivity and PPV were moderate (69.2% and 39.1%, respectively) due to the small sample size. However, for B. caballi, the sensitivity was higher with the rapid test. CONCLUSIONS: The rapid test detected T. equi and B. caballi simultaneously in the field, potentially replacing laborious cELISA testing and is recommended for import/export purposes. The test can also be helpful for the differential diagnosis of clinical cases, since seropositivity may rule out equine piroplasmosis since it does not indicate current or active infection.

Evaluation of a novel triplex immunochromatographic test for rapid simultaneous detection of norovirus, rotavirus, and adenovirus on a single strip test.

BACKGROUND: Acute gastroenteritis is one of the major causes of morbidity and mortality in young children worldwide. Among these, rotavirus, norovirus, and adenovirus have been reported as the primary viral pathogens associated with the disease. Rapid diagnosis of viral pathogens is crucial when diarrhea outbreaks occur to ensure the timely administration of appropriate treatment and control measures. METHODS: We evaluated three immunochromatographic test kits designed for the detection of norovirus, rotavirus, and adenovirus in 71 stool specimens collected from children with diarrhea who visited clinics in Japan. The first kit is a triplex immunochromatographic test kit designed for simultaneous detections of norovirus, rotavirus, and adenovirus on a single strip (this kit was referred to as IC-A). The other two immunochromatographic test kits are a dual detection kit for rotavirus and adenovirus, and a single detection kit for norovirus (IC-B). The RT-PCR/PCR was used as the gold standard method. RESULTS: The results revealed that both IC-A and IC-B kits exhibited the same level of sensitivity of detection for rotavirus (72.7%) and adenovirus (22.7%), although the detection rate was lower than that of the RT-PCR/PCR method. However, there was a slight difference in the sensitivity of detection for norovirus between IC-A and IC-B, at 86.7% and 93.3%, respectively. The sensitivity of detection for adenovirus of both kits was relatively lower than those of RT-PCR method. This could be due to low viral load of adenovirus in clinical specimens below the detection limit of IC-A and IC-B kits. However, both immunochromatographic test kits (IC-A and IC-B) exhibited 100% specificity for norovirus, rotavirus, and adenovirus. CONCLUSIONS: The triplex immunochromatographic test kit (IC-A) designed for simultaneous detection of norovirus, rotavirus, and adenovirus has been proved to be more practical and convenient than the use of single or dual detection kits with more or less the same sensitivity and specificity of detections.

Lateral Flow Immunochromatographic Assay for Competitive Detection of Crustacean Allergen Tropomyosin Using Phage-Displayed Shark Single-Domain Antibody.

The common food allergy crustacean tropomyosin (TM) poses a significant food safety challenge, which requires rapid and sensitive methods for screening TM in food. Herein, the variable new antigen receptor (VNAR) single-domain antibodies specific for the crustacean TM were isolated from a naïve phage-displayed shark VNAR library. Subsequently, a lateral flow immunochromatographic assay (LFIA) based on the gold nanoparticle-labeled phage-displayed shark VNAR (AuNPs@PSV) probe was developed for the detection of TM in food. The AuNPs@PSV-LFIA took 15 min for one test and had a visual limit of detection (vLOD) of 0.1 µg/mL and an instrumental LOD of 0.02 µg/mL. Good selectivity, accuracy, precision, and stability were confirmed for the AuNPs@PSV-LFIA. Moreover, the test results of 21 commercially available food products consisted of the allergen labels and were validated by a commercial ELISA kit. Therefore, this work demonstrated the great potential of VNAR for detecting TM in food by LFIA.

Development and evaluation of a test strip for the rapid detection of antibody against equine infectious anemia virus.

Equine infectious anemia (EIA) is a contagious disease of horses caused by the equine infectious anemia virus (EIAV). The clinical signs at the acute phase include intermittent high fever, thrombocytopenia, hemorrhage, edema, and anemia. The clinical signs at chronic and relapsing subclinical levels include emaciation and progressive weakness. Surviving horses become lifelong carriers because of the integration of the viral genome into that of the host, and these horses can produce and transmit the virus to other animals. This increases the difficulty of imposing practical control measures to prevent epidemics of this disease. Serological tests measuring the antibodies in equine sera are considered to be a reliable tool for the long-term monitoring of EIA. However, the standard serological tests for EIV either have low sensitivity (e.g., agar gel immunodiffusion test, AGID) or are time consuming to perform (e.g., ELISA and western blotting). The development of a rapid and simple method for detecting the disease is therefore critical to control the spread of EIA. In this study, we designed and developed a colloidal gold immunochromatographic (GICG) test strip to detect antibodies against EIAV based on the double-antigen sandwich. Both the p26 and gp45 proteins were used as the capture antigens, which may help to improve the positive detection rate of the strip. We found that the sensitivity of the test strip was 8 to 16 times higher than those of two commercially available ELISA tests and 128 to 256 times higher than AGID, but 8 to 16 times lower than that of western blotting. The strip has good specificity and stability. When serum samples from experimental horses immunized with the attenuated EIAV vaccine (n = 31) were tested, the results of the test strip showed 100% coincidence with those from NECVB-cELISA and 70.97% with AGID. When testing clinical serum samples (n = 1014), the test strip surprisingly provided greater sensitivity and a higher number of "true positive" results than other techniques. Therefore, we believe that the GICG test strip has demonstrated great potential in the field trials as a simple and effective tool for the detection of antibodies against EIAV. KEY POINTS: • A colloidal gold immunochromatographic (GICG) fast test strip was developed with good specificity, sensitivity, stability, and repeatability • The test strip can be used in point-of-care testing for the primary screening of EIAV antibodies • Both the p26 and gp45 proteins were used as the capture antigens, giving a high positive detection rate in the testing of experimentally infected animal and field samples.

Development and evaluation of mild TBI rapid diagnostic strips based on GFAP labeled with quantum dots / 军事医学

Objective To establish an auxiliary method for diagnosis of mild traumatic brain injury based on serum GFAP rapid detection test strips using immunochromatographic technology labeled with quantum dot microspheres.Methods The quantum dot microspheres were coupled with GFAP antibodies.The detection conditions were optimized to obtain the fluorescence probe in order to prepare the immunochromatographic test strips.An auxiliary diagnostic method was established after optimization of detection conditions.Finally,the auxiliary diagnostic effect of the test strips was evaluated using clinical samples.Results The serum concentration of GFAP could be detected by the optimized test strips within 13 mins with a detection limit of 0.15 ng/mL,and no more than 70μL of the serum sample was required.In addition,good reproducibility was achieved by different batches of test strips(CV=10.7%).The detection sensitivity and specificity of the strips to mild traumatic brain injury using 51 clinical samples were 95.24%and 96.67%respectively,indicating good effects of detection.Conclusion The developed test strips are user-friendly with reliable results,which can facilitate field rapid diagnosis of mild traumatic brain injury in complicated wartime environments.