Search Results (138)

Nipah virus (NiV) and Hendra virus (HeV), which both belong to the genus henipavirus, are zoonotic pathogens that cause severe systemic, neurological, and/or respiratory disease in humans and a variety of mammals. Therefore, monitoring viral prevalence in natural reservoirs and rapidly diagnosing cases of henipavirus infection are critical to limiting the spread of these viruses. Current laboratory methods for detecting NiV and HeV include virus isolation, reverse transcription quantitative real-time PCR (RT-qPCR), and antigen detection via an enzyme-linked immunosorbent assay (ELISA), all of which require highly trained personnel and specialized equipment. Here, we describe the development of a point-of-care customized immunochromatographic lateral flow (ILF) assay that uses recombinant human ephrin B2 as a capture ligand on the test line and a NiV-specific monoclonal antibody (mAb) on the conjugate pad to detect NiV and HeV. The ILF assay detects NiV and HeV with a diagnostic specificity of 94.4% and has no cross-reactivity with other viruses. This rapid test may be suitable for field testing and in countries with limited laboratory resources. Full article

Canine distemper, a fatal and highly transmissible disease caused by the canine distemper virus (CDV), poses a major threat to the companion animal industry. An urgent need exists for a rapid, specific, and simple method for the detection of this disease in order to improve its prevention and control. In this research, two monoclonal antibodies (mAbs), 1D3E9 and 1H9B7, were prepared, both of which specifically recognize the nucleoprotein (N protein) of CDV, and an immunochromatographic assay for CDV detection was subsequently developed using these mAbs. The results showed that both mAbs belong to the IgG1 subclass with kappa light chains. 1D3E9 was found to recognize the linear epitope ⁴¹⁰AGPKQSQITFLH⁴²¹, while 1H9B7 targeted the epitope ⁴⁵⁰HFNDERFPGH⁴⁵⁹. The test strips exhibited high specificity and good stability for up to two months when stored at 4, 25, and 37 °C. The assay exhibited a sensitivity of 10^2.39 TCID₅₀/0.1 mL. When compared with RT-PCR for detecting CDV in clinical samples, the concordance rate was 91.67%. Thus, this method shows great potential for facilitating rapid on-site detection of CDV and could be highly beneficial from the viewpoint of disease surveillance and control. Full article

At crime scenes, apart from the detection of blood, it may be important to determine whether a person was alive at the time of blood deposition. Based on the rapid onset of fibrinolysis after death, this pathway could be considered to identify potential biomarkers for postmortem blood. Fibrinolysis is the natural process that breaks down blood clots after healing a vascular injury. One of its products, D-dimer, could be a potential biomarker for postmortem blood. SERATEC^® (SERATEC^® GmbH, Göttingen, Germany) has developed the PMB immunochromatographic assay to simultaneously detect human hemoglobin and D-dimer. The main goals of this study were to assess the possibility of using this test to detect postmortem blood, evaluate D-dimer levels in antemortem, menstrual, and postmortem blood, and assess the ability to obtain STR profiles from postmortem blood. Except for one degraded sample, all postmortem blood samples reacted positively for the presence of D-dimer using the SERATEC^® PMB test. All antemortem blood samples from living individuals showed negative results for D-dimer detection, except for one liquid sample with a weak positive result, probably due to pre-existing health conditions. Menstrual blood samples gave variable results for D-dimer. The DIMERTEST^® Latex assay was used for semi-quantitative measurement of D-dimer concentrations, with postmortem and menstrual blood yielding higher D-dimer concentrations compared to antemortem blood. Full STR profiles were developed for all postmortem samples tested except for one degraded sample, pointing to the possibility of not only detecting postmortem blood at the crime scene but also the potential identification of the victim. Full article

Background/Objectives: The COVID-19 pandemic has highlighted the urgent need for rapid, accurate, and accessible diagnostic testing to effectively manage and contain the spread of SARS-CoV-2. RT-PCR is widely recognized as the gold standard for SARS-CoV-2 detection due to its high sensitivity and specificity. However, RT-PCR testing requires specialized laboratory equipment, highly trained personnel, and extended processing times, which limits its feasibility for large-scale screening and point-of-care applications. This study aims to systematically evaluate the diagnostic performance of RT-PCR and a colloidal gold immunochromatographic assay (GICA). Methods: By comparing these two methods, we seek to determine a GICA’s effectiveness as a complementary or alternative diagnostic tool, particularly in resource-limited settings and scenarios requiring rapid, large-scale testing. We assessed the following key clinical parameters: sensitivity, specificity, NPV, PPV, and accuracy. Additionally, we investigated the correlation between GICA signal intensity and RT-PCR Ct values using regression analysis, receiver operating characteristic curve analysis, and the calculated area under the curve. Results: Our findings indicate that while RT-PCR exhibits superior sensitivity, GICA results demonstrate a strong correlation with RT-PCR results and provide a rapid, cost-effective alternative for SARS-CoV-2 detection. Unlike RT-PCR, which requires extensive resources and prolonged turnaround times, a GICA delivers results within 20 min, making it a viable option for decentralized testing and real-time public health interventions. Conclusions: These results suggest that a GICA can serve as a complementary diagnostic tool alongside RT-PCR, particularly in resource-limited settings and high-throughput screening scenarios. By integrating GICAs into broader testing strategies, healthcare systems can enhance early detection efforts, improve accessibility to diagnostics, and strengthen pandemic response measures. Full article

The development of rapid, sensitive and cost-effective lateral flow assays is crucial for the detection of mycotoxins, ideally at the point-of-care level. This study presents the design and optimization of a competitive lateral flow assay based on gold nanoparticles (AuNPs) for the detection of zearalenone in food samples. Beginning with the synthesis and functionalization of gold nanoparticles, it proceeds to compare the immobilization of antibodies using chemical conjugation and physical adsorption binding strategies, upon optimizing parameters including the pH, antibody concentration and blocking conditions to enhance the stability of the prepared bioconjugates. The bioconjugates are characterized using UV–visible absorption spectroscopy and dynamic light scattering to monitor changes in the spectra and hydrodynamic size of AuNPs upon the addition of antibodies. The assessment of these bioconjugates is based on their ability to bind and manifest a color, developed due to nanoparticle binding with the test zone on the strip with the toxin–protein conjugate. The lateral flow immunochromatographic assay (LFIA) strips are then prepared by dispensing a control line (IgG) and test line (toxin–protein conjugate) on a nitrocellulose membrane using a lateral flow strip dispenser. The sensitivity of the LFIA strips is evaluated after standardizing the conditions by varying the concentration of zearalenone in the spiked samples and optimizing the running buffer solution. The limit of detection and limit of quantification under optimized conditions are determined to be 0.7 ng/mL and 2.37 ng for zearalenone-spiked samples. Furthermore, the mean pixel intensity and RGB values are plotted against the concentration of zearalenone, which can be used in a colorimetric smartphone-based application for the quantification of the amount of mycotoxin in the sample. Full article

Feline leukemia virus (FeLV) and Feline immunodeficiency virus (FIV) are globally prevalent retroviral pathogens that pose significant health risks to domestic cats. This study aimed to compare the diagnostic performance of two point-of-care—the immunochromatographic assay (ICA) and the RNase hybridization-assisted amplification (RHAM) test kit—against reverse transcription quantitative polymerase chain reaction (RT-qPCR), the current gold standard for FeLV and FIV detection. For FeLV detection, ICA demonstrated a sensitivity of 86.89%, specificity of 96.55%, accuracy of 90.00%, and precision of 98.15%, while for FIV detection, the assay showed a sensitivity of 75.86%, specificity of 88.52%, accuracy of 84.44%, and precision of 75.86%. In contrast, the RHAM test exhibited superior performance, with FeLV detection sensitivity of 93.44%, specificity of 98.28%, accuracy of 94.44%, and precision of 98.28%. For FIV detection, RHAM demonstrated a sensitivity of 75.86%, specificity of 100%, accuracy of 92.22%, and precision of 100%. Additionally, the RHAM assay significantly reduced detection time compared to RT-qPCR, enabling expedited clinical decision-making, alleviating laboratory workload, and lowering diagnostic costs. These benefits are particularly relevant in veterinary settings with limited access to PCR-based diagnostics, where the RHAM assay represents a rapid, reliable, and resource-efficient alternative for FeLV and FIV detection. Full article

Procymidone (PCM) is an effective, low-toxicity fungicide commonly used to control plant diseases in grains, vegetables, and fruits. Its usage has significantly increased in recent years, resulting in higher residues in vegetables. This study developed a sensitive and rapid immunoassay method utilizing a gold- and fluorescence-labeled monoclonal antibody (mAb) for detecting PCM residues in vegetable samples. Under optimal conditions, the fluorescent microsphere-labeled monoclonal antibody immunochromatographic strips achieved a limit of detection (LOD) of 1.67 ng/mL, with a visual LOD of 50 ng/mL. Intra-batch accuracy ranged from 94.98% to 103.82%, with a coefficient of variation (CV) of 1.97% to 8.26%. Inter-batch accuracy ranged from 96.16% to 102.51%, with a CV of 4.62% to 8.91%. The visual detection range of the gold nanoparticle-labeled monoclonal antibody immunochromatographic strips was 50 to 200 ng/g. The method demonstrated excellent performance in actual vegetable samples, confirming its applicability across various matrices. This dual-method approach enables rapid screening of negative samples with gold test strips, followed by accurate quantitative analysis of positive samples using fluorescent test strips, thereby enhancing efficiency and addressing diverse detection needs. Consequently, this method holds significant market potential for practical applications. Full article

Background and Objectives: Chlamydial infection is the most common asymptomatic infection worldwide. Despite all national programs, strategies and guidelines, chlamydial infection is still the leading infection worldwide, especially in young populations. We have tried to summarize the best diagnostic tools for its detection. Materials and Methods: In the study, 225 sexually active patients who were tested for chlamydial infection at the Institute of Public Health Kragujevac participated. Results: Combinations of direct immunofluorescence (DIF) and a rapid lateral immunochromatographic test (RT) and combinations of an RT and immunoglobulin G (IgG) do not improve diagnostic efficiency when compared to a rapid test that individually had the best parameters. In situations that require high specificity, the recommended combination is RT/IgA, which as a highly specific test has few false positive results, while the combinations of DIF + RT and RT + IgG, although showing a specificity of 100%, have low sensitivity (33.30%), due to which we prefer the RT/IgA combination. The combinations DIF + RT, DIF + RT + IgG and RT + IgG, although with low sensitivity, have the highest values of specificity, and the positive predictive value (PPV) and negative predictive value (NPV) show the highest values of the extended Youden index of 130.30% and the highest values of total diagnostic accuracy of 97.00%. Based on the results of the extended Youden index, taking into account PPV and NPV, the RT/IgA combination shows the highest value of 94.60%, as well as the highest value of total diagnostic accuracy of 93.00%. Conclusions: “Two or more positive tests” or “any test positive” did not improve the diagnostic efficiency compared to a single “rapid test”. Full article

Animal-derived foods constitute a crucial source of nutrients for humans. The judicious application of steroid hormones in the breeding process can serve multiple purposes, including growth promotion, weight gain, and anti-inflammatory effects, among others. However, excessive misuse poses a considerable risk to both food safety and consumer health. Currently, the primary means of detecting steroid hormones involve liquid chromatography, gas chromatography, and their combination with mass spectrometry. These methods necessitate advanced instrumentation, intricate pretreatment procedures, and the expertise of specialized laboratories and technicians. In recent years, the swift evolution of analytical science, technology, and instrumentation has given rise to various rapid detection techniques for steroid hormone residues, providing a robust technical foundation for ensuring food safety. This review commences by delineating the roles of steroid hormones, the associated residue hazards, and the pertinent residue restriction standards. Subsequently, it delves deeply into the analysis of the most recent rapid detection techniques for steroid hormones, ultimately culminating in an assessment of the challenges currently confronting the field, along with an exploration of potential future advancements. We sincerely hope that this review will inspire and provide valuable insights to the pertinent researchers. Full article

Occult HCV infection (OCI) is defined by the presence of HCV RNA in hepatocytes and/or peripheral blood mononuclear cells (PBMCs) without detectable HCV RNA or anti-HCV antibodies in plasma. OCI is underrecognized and may contribute to HCV transmission. This study estimated OCI prevalence and associated risk factors in adults from Mexico City. Methods: A retrospective cross-sectional study was conducted, analyzing 507 general population volunteers. Demographic data and potential risk factors were collected via questionnaire. Anti-HCV detection was performed using two techniques: immunochromatographic rapid test and chemiluminescent microparticle immunoassay (CMIA). Nested PCR was employed to detect HCV RNA in plasma and PBMCs. Positive samples were genotyped through sequencing and phylogenetic analysis of the Core/E1 region. Results: Of 507 participants, four were anti-HCV positive. HCV RNA was found in PBMCs of 27 individuals, while plasma samples tested negative, indicating a 5.3% OCI prevalence. OCI was significantly associated with blood donation (p = 0.015), drug use (p = 0.019), particularly cocaine (p = 0.001), and endoscopy (p = 0.043). Genotypes 1b, 1a, 2b, 3a, and 2j were detected in OCI cases. Conclusions: OCI prevalence in Mexico City’s general population is notable, with significant links to blood donation, cocaine use, and endoscopy. Enhanced diagnostic strategies are crucial to detect OCI and mitigate HCV transmission. Full article

Background/Objectives: Rabies is almost invariably fatal once clinical symptoms manifest. Timely and accurate diagnosis is essential for effective treatment and prevention. Dogs are the principal reservoirs of the virus, particularly in developing nations, highlighting the importance of precise diagnostic and control measures to prevent human cases. This systematic review and meta-analysis assessed the accuracy of laboratory tests for diagnosing rabies in humans and dogs. Methods: The PubMed database was searched for published studies on rabies diagnosis between 1990 and 2024. Following PRISMA statement recommendations, we included 60 studies that met the selection criteria. Results: The results demonstrated the effectiveness of immunological tests like the Enzyme-Linked Immunosorbent Assay (ELISA) and molecular tests such as Reverse Transcription Polymerase Chain Reaction (RT-PCR) for both humans and dogs. In this study, the Direct Fluorescent Antibody Test (DFAT) exhibited lower diagnostic performance, with an area under the curve for false positive rates (AUC_FPR = 0.887). In contrast, ELISA (AUC_FPR = 0.909) and RT-PCR (AUC_FPR = 0.905) provided more consistent results. Notably, the Rapid Immunochromatographic Test (RIT) showed the best performance (AUC_FPR = 0.949), highlighting its superior diagnostic capabilities compared to DFAT. Conclusions: These findings underscore the need to modernize rabies diagnostic protocols by incorporating advanced methodologies to improve diagnostic accuracy, reduce transmission, and decrease mortality rates. Full article

Pesticide residues still pose a risk to human health. With the rapid development of rapid testing technology, the levels of different types of pesticide residues in agricultural products can be identified in a shorter period; thus, the safety of food can be guaranteed. However, the effectiveness of commercially available testing products has yet to be evaluated. In this study, colloidal gold immunochromatographic qualitative testing products manufactured by 34 companies were tested for their assay performance on Emamectin Benzoate, Isocarbophos, and fipronil with standardized cowpea samples. The results indicated that most of the evaluated products were identified as having ‘passed’. Most pesticide residue rapid test immunoassay products can be considered ideal means for testing certain pesticide residues. However, further evaluation of pesticide residue rapid test immunoassay products is needed, as detection technologies are still developing. Full article

In this study, a novel rapid immunochromatographic (IC) test for African swine fever virus (ASFV) antibodies is presented. An immunochromatographic test (IC) is a detection technique that combines membrane chromatography with immunolabeling. This approach saves time for antibody preparation, resulting in a shorter production cycle. p54 is an important structural protein of African swine fever, and an ideal protein for serotype diagnosis. Gold nanoparticles are attached to the ASFV p54-Fc fusion protein, and the ASFV-specific antigen p54 and Staphylococcus aureus protein A (SPA) are labeled on a nitrocellulose membrane, at positions T and C, respectively. We developed a SPA double sandwich IC test strip, and assessed its feasibility using ASFV p54 and p54-Fc fusion proteins as antigens. ASFV p54 and p54-Fc fusion proteins were expressed and purified. A sandwich cross-flow detection method for p54, which is the primary structural protein of ASFV, was established, using colloidal gold conjugation. Our method can detect ASFV antibodies in field serum samples in about 15 min using a portable colloidal gold detector, demonstrating high specificity and sensitivity (1:320), and the coincidence rate was 98% using a commercial ELISA kit. The dilution of the serum sample can be determined by substituting the absorbance (T-line) interpreted by portable devices into the calibration curve function formula of an African swine fever virus standard serum. In summary, our method is rapid, cost-effective, precise, and highly selective. Additionally, it introduces a new approach for constructing IC test strips using SPA protein without antibody preparation, making it a reliable on-site antibody test for ASFV. Full article

The livestock industry uses ofloxacin, an antibiotic, to prevent several animal diseases; however, the overdose of ofloxacin used in animal farming treatments may appear in food products and cause some adverse human health effects. Hence, there is an immediate need to develop a method suitable for on site large-scale detection of ofloxacin residues in animal-derived foods. This study aimed to prepare a monoclonal antibody with high sensitivity and affinity for ofloxacin by re-synthesizing the ofloxacin hapten and synthesizing the corresponding complete antigen. The IC₅₀ of the enzyme-linked immunosorbent assay (ic-ELISA) was 0.13 ng/mL, and the detection limit was 0.033 ng/mL. The visual detection limit of the established colloidal gold immunochromatographic test strip, for the visual detection of actual samples, was 1 ng/g. In summary, this work establishes a rapid detection method of ofloxacin residues on the basis of colloidal gold immunochromatography that is suitable for actual detection. Full article

Rotavirus group A (RVA) is a major cause of pediatric acute gastroenteritis (AGE). Vaccination is an effective public health strategy and Angola implemented it in 2014. This hospital-based study aimed to estimate the prevalence of RVA infection and the severity of AGE in children under five years of age treated at six hospitals in Luanda Province. Between April 2021 and May 2022, 1251 fecal samples were screened by an immunochromatographic rapid test (SD Bioline). Data on socio-demographic profile, nutritional status, and clinical assessment were obtained. The association of RVA infection and AGE severity with possible risk factors was evaluated with a binary logistic regression model. Overall, the detection rate was 57.8% and girls tend to be more often infected than boys (55.2%). Infection was more common in the youngest group (1 to 6 months, 60.3%). Important sources of RVA infection were drinking water kept in tanks (57.9%) and private sanitary facilities with piped water (61%). Surprisingly, according to the Vesikari Scale score, the most severe symptoms were observed in children vaccinated with two doses (80.7%). RVA prevalence remains high despite vaccination, and further studies should address the association between infection sources and disease severity, as well as the causes underlying vaccine (un)effectiveness. Full article