Rapid Lateral Flow Immunochromatographic Assay Research Articles

Technical performance of a lateral flow immunoassay for detection of anti-SARS-CoV-2 IgG in the outpatient follow-up of non-severe cases and at different times after vaccination: comparison with enzyme and chemiluminescent immunoassays.

ABSTRACTThis study assessed the technical performance of a rapid lateral flow immunochromatographic assay (LFIA) for the detection of anti-SARS-CoV-2 IgG and compared LFIA results with chemiluminescent immunoassay (CLIA) results and an in-house enzyme immunoassay (EIA). To this end, a total of 216 whole blood or serum samples from three groups were analyzed: the first group was composed of 68 true negative cases corresponding to blood bank donors, healthy young volunteers, and eight pediatric patients diagnosed with other coronavirus infections. The serum samples from these participants were obtained and stored in a pre-COVID-19 period, thus they were not expected to have COVID-19. In the second group of true positive cases, we chose to replace natural cases of COVID-19 by 96 participants who were expected to have produced anti-SARS-CoV-2 IgG antibodies 30-60 days after the vaccine booster dose. The serum samples were collected on the same day that LFIA were tested either by EIA or CLIA. The third study group was composed of 52 participants (12 adults and 40 children) who did or did not have anti-SARS-CoV-2 IgG antibodies due to specific clinical scenarios. The 12 adults had been vaccinated more than seven months before LFIA testing, and the 40 children had non-severe COVID-19 diagnosed using RT-PCR during the acute phase of infection. They were referred for outpatient follow-up and during this period the serum samples were collected and tested by CLIA and LFIA. All tests were performed by the same healthcare operator and there was no variation of LFIA results when tests were performed on finger prick whole blood or serum samples, so that results were grouped for analysis. LFIA’s sensitivity in detecting anti-SARS-CoV-2 IgG antibodies was 90%, specificity 97.6%, efficiency 93%, PPV 98.3%, NPV 86.6%, and likelihood ratio for a positive or a negative result were 37.5 and 0.01 respectively. There was a good agreement (Kappa index of 0.677) between LFIA results and serological (EIA or CLIA) results. In conclusion, LFIA analyzed in this study showed a good technical performance and agreement with reference serological assays (EIA or CLIA), therefore it can be recommended for use in the outpatient follow-up of non-severe cases of COVID-19 and to assess anti-SARS-CoV-2 IgG antibody production induced by vaccination and the antibodies decrease over time. However, LFIAs should be confirmed by using reference serological assays whenever possible.

Comparison of diagnostic accuracy for eight SARS-CoV-2 serological assays.

IntroductionSevere acute respiratory syndrome coronavirus 2 (SARS-CoV-2) serological tests have been suggested as an additional diagnostic tool in highly suspected cases with a negative molecular test and determination of seroprevalence in population. We compared the diagnostic performance of eight commercial serological assays for IgA, IgM, and IgG antibodies to the SARS-CoV-2 virus.Materials and methodsThe comparison study was performed on a total of 76 serum samples: 30 SARS-CoV-2 polymerase chain reaction (PCR)-negative and 46 SARS-CoV-2 PCR-positive patients with asymptomatic to severe disease and symptoms duration from 3-30 days. The study included: three rapid lateral flow immunochromatographic assays (LFIC), two enzyme-linked immunosorbent assays (ELISA), and three chemiluminescence immunoassays (CLIA).ResultsAgreement between IgM assays were minimal to moderate (kappa 0.26 to 0.63) and for IgG moderate to excellent (kappa 0.72 to 0.92). Sensitivities improved with > 10 days of symptoms and were: 30% to 89% for IgM; 89% to 100% for IgG; 96% for IgA; 100% for IgA/IgM combination; 96% for total antibodies. Overall specificities were: 90% to 100% for IgM; 85% to 100% for IgG; 90% for IgA; 70% for IgA/IgM combination; 100% for total antibodies. Diagnostic accuracy for IgG ELISA and CIA assays were excellent (AUC ≥ 0.90), without significant difference. IgA showed significantly better diagnostic accuracy than IgM (P < 0.001).ConclusionThere is high variability between IgM assays independently of the assay format, while IgG assays showed moderate to perfect agreement. The appropriate time for testing is crucial for the proper immunity investigation.

Suitability of two rapid lateral flow immunochromatographic assays for predicting SARS‐CoV‐2 neutralizing activity of sera

Assessment of commercial severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) immunoassays for their capacity to provide reliable information on sera neutralizing activity is an emerging need. We evaluated the performance of two commercially available lateral flow immunochromatographic assays (LFIC; Wondfo SARS‐CoV‐2 Antibody test and the INNOVITA 2019‐nCoV Ab test) in comparison with a SARS‐CoV‐2 neutralization pseudotyped assay for coronavirus disease 2019 (COVID‐19) diagnosis in hospitalized patients and investigate whether the intensity of the test band in LFIC associates with neutralizing antibody (NtAb) titers. Ninety sera were included from 51 patients with moderate to severe COVID‐19. A green fluorescent protein (GFP) reporter‐based pseudotyped neutralization assay (vesicular stomatitis virus coated with SARS‐CoV‐2 spike protein) was used. Test line intensity was scored using a 4‐level scale (0 to 3+). The overall sensitivity of LFIC assays was 91.1% for the Wondfo SARS‐CoV‐2 Antibody test, 72.2% for the INNOVITA 2019‐nCoV IgG, 85.6% for the INNOVITA 2019‐nCoV IgM, and 92.2% for the NtAb assay. Sensitivity increased for all assays in sera collected beyond day 14 after symptoms onset (93.9%, 79.6%, 93.9%, and 93.9%, respectively). Reactivities equal to or more intense than the positive control line (≥2+) in the Wondfo assay had a negative predictive value of 100% and a positive predictive value of 96.4% for high NtAb50 titers (≥1/160). Our findings support the use of LFIC assays evaluated herein, particularly the Wondfo test, for COVID‐19 diagnosis. We also find evidence that these rapid immunoassays can be used to predict high SARS‐CoV‐2‐S NtAb50 titers.

Comparison of diagnostic accuracies of rapid serological tests and ELISA to molecular diagnostics in patients with suspected coronavirus disease 2019 presenting to the hospital

ObjectivesTo assess the diagnostic performance of rapid lateral flow immunochromatographic assays (LFAs) compared with an ELISA and nucleic acid amplification tests (NATs) in individuals with suspected coronavirus disease 2019 (COVID-19). MethodsPatients presenting to a Dutch teaching hospital were eligible between 17 March and 10 April 2020, when they had respiratory symptoms that were suspected for COVID-19. The performances of six different LFAs were evaluated in plasma samples obtained on corresponding respiratory sample dates of NATs testing. Subsequently, the best performing LFA was evaluated in 228 patients and in 50 sera of a historical patient control group. ResultsIn the pilot analysis, sensitivity characteristics of LFA were heterogeneous, ranging from 2/20 (10%; 95% CI 0%–23%) to 11/20 (55%; 95% CI 33%–77%). In the total cohort, Orient Gene Biotech COVID-19 IgG/IgM Rapid Test LFA had a sensitivity of 43/99 (43%; 95% CI 34%–53%) and specificity of 126/129 (98%; 95% CI 95%–100%). Sensitivity increased to 31/52 (60%; 95% CI 46%–73%) in patients with at least 7 days of symptoms, and to 21/33 (64%; 95% CI 47%–80%) in patients with C-reactive protein (CRP) ≥100 mg/L. Sensitivity and specificity of Wantai SARS-CoV-2 Ab ELISA was 59/95 (62%; 95% CI 52%–72%) and 125/128 (98%; 95% CI 95%–100%) in all patients, respectively, but sensitivity increased to 38/48 (79%; 95% CI 68%–91%) in patients with at least 7 days of symptoms. ConclusionsThere is large variability in diagnostic test performance between rapid LFAs, but overall limited sensitivity and high specificity in acutely admitted patients. Sensitivity improved in patients with longer existing symptoms or high CRP. LFAs should only be considered as additional triage tools when these may lead to the improvement of hospital logistics.

Ultrasensitive detection of praziquantel in sea bass (Lateolabrax japonicus) using a lateral flow immunochromatographic assay

ABSTRACT Praziquantel (PZQ) is a compound that usually used as insecticide, drug residue could be harm to human health. In this study, we have developed a simple, sensitive, and rapid lateral flow immunochromatographic assay (LFIA) for the detection of PZQ in fish (Lateolabrax Japonicus). We produced a sensitive mAb using enzyme-linked immunosorbent assay with half-maximal inhibitory concentration (2A11, IC50) of 2.06 ng/mL. The coating antigen (PZQ-HS-GA-OVA) and goat anti-mouse IgG antibody were sprayed onto a nitrocellulose membrane as the test and control lines, respectively. Under optimal conditions, the cut-off limits for PZQ detection on the test strips were determined to be 5 ng/mL in both 0.01 M phosphate buffered saline and fish samples, and results were obtained within 5 min. Our data suggests that this LFIA can be used for the sensitive, rapid, and specific on-site screening for PZQ in fish.

Norovirus Infection among Children Under 5 Years of Age In Niger-Delta Zone, Nigeria

Background: Norovirus is now recognized as a major cause of gastroenteritis among children worldwide. This study aimed to determine the prevalence of Norovirus infection among children that are less than five years of age in Niger-Delta zone, Nigeria. Methods: A total of 263 subjects consisted of 163 children with diarrhea attending Paediat-ric clinics at the Central Hospital, Warri and Federal Medical Center, Yenagoa as well as 100 aged- and sex-matched healthy individuals that served as controls were recruited for this study. Demographic information was obtained through the aid of a well-structured questionnaires. Norovirus was detected by using a rapid lateral flow immunochromatographic assay kit (Biopanda reagents, Belfast, United Kingdom). Results: The overall prevalence of Norovirus infection was 15.3%. The prevalence of Norovirus infection was significantly higher in Delta State than in Bayelsa State (22.9 % vs. 6.7%; OR= 3.6615; 95% CI = 1.378, 9.725; P=0.0092). Children that are less than 5 years of age attending day care centers are greatly affected by Norovirus infection (P=0.0044). Also, poor hand hygiene practice was also a significant risk factor for Norovirus infection among study subjects (P=0.0036). Furthermore, secretors were found to have a 1 to 334 fold increased risk of acquiring Norovirus infection in Delta State than in Bayelsa State (OR=19.28, 95% C.I, 1.1102, 334.68, P=0.0422). Conclusion: The need for routine screening for Norovirus infection among children with diarrhea is advocated. Data from this study as well suggests that genetic and environmental factors play a role in Norovirus infection.

Upconversion luminescence nanoparticles-based immunochromatographic assay for quantitative detection of triamcinolone acetonide in cosmetics

Triamcinolone acetonide (TCA) abuse in cosmetics is a common phenomenon. A rapid lateral flow immunochromatographic assay (ICA) was developed for the quantitative detection of TCA using a probe based on upconversion luminescence nanoparticles. Lanthanide-doped upconversion nanoparticles (UCNPs) were synthesized in a system comprising water and ethylene glycol, and a silicon dioxide layer was covered at the carboxyl site. A binding site protection strategy was used to decrease the background signal of UCNPs-ICA. Using dexamethasone derivative as a coating antigen, the optimal UCNPs-ICA exhibits good dynamic linear detection for TCA in the range 1.0-100 ng mL-1 with a median inhibitory concentration of 9.8 ng mL-1. The detection limits for TCA in a cosmetic sample are 20 μg kg-1. The pretreatment of samples only needs dilution with water, suggesting the assay can quantitate TCA on-site using a portable upconversion luminescence reader with a cumulative analysis time of only 10 min.

Immunochromatographic test for rapid serological diagnosis of human angiostrongyliasis

ObjectivesThe serological diagnosis of human infection with Angiostrongylus cantonensis remains problematic because there are no commercially available validated tests. Most laboratories use domestically prepared tests such as the enzyme-linked immunosorbent assay (ELISA) or immunoblotting. Since laboratory facilities are not always available in endemic areas, we developed and assessed a rapid lateral flow immunochromatographic assay (AcQuickDx Test) to detect anti-A. cantonensis antibodies in human serum. MethodsThe test device was assembled with purified 31-kDa glycoprotein as diagnostic antigen and with gold-labelled anti-human immunoglublin-G as the detector reagent. A total of 97 serum samples were tested – 19 samples from clinically diagnosed patients with detectable A. cantonensis-specific antibody in immunoblotting; 43 samples from patients with other parasitic diseases, i.e. gnathostomiasis (n=13), toxocariasis (n=2), trichinellosis (n=2), hookworm infection (n=4), filariasis (n=5), cysticercosis (n=9), paragonimiasis (n=2), opisthorchiasis (n=3), and malaria (n=3); and 35 samples from normal healthy subjects. ResultsThe sensitivity, specificity, positive predictive value and negative predictive value of AcQuickDx Test to detect anti-A. cantonensis specific antibodies in serologically confirmed angiostrongyliasis cases, were 100%, 98.72%, 95% and 100%, respectively. Positive AcQuickDx was observed in 1 of 4 cases with hookworm infections. No positive AcQuickDx was observed in cases with other parasitic diseases, and the individual healthy subjects. ConclusionsAcQuickDx Test is rapid, highly sensitive and specific, and easy to perform without additional equipment or ancillary supplies. It yields results that are interpreted visually, and possesses a long shelf-life at room temperature. Thus, it can be applied as an additional test for clinical diagnostic support of angiostrongyliasis either in conventional laboratories or for remote areas where laboratory infrastructure is not available.

Visual and rapid lateral flow immunochromatographic assay for enrofloxacin using dyed polymer microspheres and quantum dots

The authors describe two kinds of immunochromatographic assays. The first is based on the use of dyed polymer microspheres (MICA), the another on the use of quantum dots (QICA). Both enable visual detection of enrofloxacin (ENR) in animal tissue and milk. Both the MICA and the QICA have visual limits of detection of 1 μg·L−1 when working in buffer, of 5 μg·kg−1 in case of animal tissue, and of 10 μg·L−1 in case of milk. Other quinolones do not interfere. The MICA and QICA described here are convenient and fairly rapid in that the detection process (including sample pretreatment and assay) takes 20 min only which is far less than the commercial enzyme-linked immunosorbent assay (ELISA) test kit which requires 120 min. The MICA and QICA are more sensitive than the immunochromatographic assay using colloidal gold labels and the same polyclonal antibody. The results of analysis of spiked samples via MICA and QICA are in good agreement with those obtained by the commercial ELISA test kit.

Molecular diversity and frequency of the diarrheagenic enteric protozoan Giardia duodenalis and Cryptosporidium spp. in a hospital setting in Northern Spain.

BackgroundHuman giardiosis and cryptosporidiosis are caused by the enteric protozoan parasites Giardia duodenalis and Cryptosporidium spp. Both pathogens are major contributors to the global burden of diarrhoeal disease, affecting primarily children and immunodebilitated individuals in resource-poor settings. Giardiosis and cryptosporidiosis also represent an important, often underestimate, public health threat in developed countries. In Spain only limited information is currently available on the epidemiology of these infections. Molecular data on the diversity, frequency, geographical distribution, and seasonality of G. duodenalis assemblages/sub-assemblages and Cryptosporidium species/sub-genotypes are particularly scarce.MethodsA longitudinal molecular epidemiological survey was conducted between July 2015 to September 2016 in patients referred to or attended at the Hospital San Pedro (La Rioja, Northern Spain) that tested positive for G. duodenalis (N = 106) or Cryptosporidium spp. (N = 103) by direct microscopy and/or a rapid lateral flow immunochromatographic assay. G. duodenalis infections were subsequently confirmed by real-time PCR and positive isolates assessed by multi-locus sequence genotyping of the glutamate dehydrogenase and β-giardin genes of the parasite. Cryptosporidium species and sub-genotypes were investigated at the 60 kDa glycoprotein or the small subunit ribosomal RNA genes of the parasite. Sociodemographic and clinical parameters of infected patients were also gathered and analysed.Principal findingsOut of 90 G. duodenalis-positive isolates by real-time PCR a total of 16 isolates were successfully typed. AII (44%, 7/16) was the most prevalent sub-assemblage found, followed by BIV (31%, 5/16) and BIII (19%, 3/16). A discordant genotype result AII/AIII was identified in an additional (6%, 1/16) isolate. No mixed infections A+B were detected. Similarly, a total of 81 Cryptosporidium spp. isolates were successfully typed, revealing the presence of C. hominis (81%, 66/81) and C. parvum (19%, 15/81). Obtained GP60 sequences were assigned to sub-type families Ib (73%, 59/81) within C. hominis, and IIa (7%, 6/81) and IId (2%, 2/81) within C. parvum. A marked inter-annual variation in Cryptosporidium cases was observed.ConclusionsHuman giardiasis and cryptosporidiosis are commonly identified in patients seeking medical care in Northern Spain and represent a more important health concern than initially thought. Assemblage A within G. duodenalis and sub-genotype IbA10G2 within C. hominis were the genetic variants of these parasite species more frequently found circulating in the population under study. Molecular data presented here seem to suggest that G. duodenalis and Cryptosporidium infections arise through anthroponotic rather than zoonotic transmission in this Spanish region.

Comparison of BD Directigen™ EZ RSV and Binax NOW® RSV tests for rapid detection of respiratory syncytial virus from nasopharyngeal aspirates in a pediatric population

The BD Directigen™ EZ RSV (BD) assay and the Binax NOW ® RSV (BN) assays are lateral flow immunochromatographic assays used in the rapid diagnosis of respiratory syncytial virus (RSV) infection. A prospective study was undertaken to compare the performance characteristics of the BD and BN assays using 99 fresh nasopharyngeal aspirate specimens from children. All specimens were cultured by tube cultures and R-mix shell vials. Culture-negative specimens that tested positive by 1 or both antigen tests were analyzed by reverse transcriptase polymerase chain reaction (RT-PCR) for the presence of RSV nucleic acids. Specimens positive by culture and/or RT-PCR were considered true positives. The sensitivity, specificity, positive predictive value, and negative predictive value for BD were 90%, 94%, 94%, and 90%, respectively, and those for BN were 90%, 100%, 100%, and 90% respectively. The overall agreement between the 2 assays was 93% (confidence interval, 86.3–96.6%). Three specimens negative by both assays were positive by viral culture. The rapid lateral flow immunochromatographic assays were easy to perform and easy to interpret, and the results are available in less than 30 min. The reduced turnaround time offered by these assays is particularly useful in the rapid detection of RSV infections in children from outpatient settings.

Rapid, Sensitive, and Specific Lateral-Flow Immunochromatographic Device To Measure Anti-Anthrax Protective Antigen Immunoglobulin G in Serum and Whole Blood

Evidence from animals suggests that anti-anthrax protective antigen (PA) immunoglobulin G (IgG) from vaccination with anthrax vaccine adsorbed (AVA) is protective against Bacillus anthracis infection. Measurement of anti-PA IgG in human sera can be performed using either enzyme-linked immunosorbent assay or fluorescent covalent microsphere immunoassay (ELISA) (R. E. Biagini, D. L. Sammons, J. P. Smith, B. A. MacKenzie, C. A. Striley, V. Semenova, E. Steward-Clark, K. Stamey, A. E. Freeman, C. P. Quinn, and J. E. Snawder, Clin. Diagn. Lab. Immunol. 11:50-55, 2004). Both these methods are laboratory based. We describe the development of a rapid lateral-flow immunochromatographic assay (LFIA) test kit for the measurement of anti-PA IgG in serum or whole-blood samples (30-microl samples) using colloidal gold nanoparticles as the detection reagent and an internal control. Using sera from 19 anthrax AVA vaccinees (anti-PA IgG range, 2.4 to 340 microg/ml) and 10 controls and PA-supplemented whole-blood samples, we demonstrated that the LFIA had a sensitivity of approximately 3 microg/ml anti-PA IgG in serum and approximately 14 microg/ml anti-PA IgG in whole blood. Preabsorption of sera with PA yielded negative anti-PA LFIAs. The diagnostic sensitivity and specificity of the assay were 100% using ELISA-measured anti-PA IgG as the standard. This kit has utility in determining anti-PA antibody reactivity in the sera of individuals vaccinated with AVA or individuals with clinical anthrax.