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A rapid test for detecting total immunoglobulins directed towards the nucleocapsid protein (N) of severe acute syndrome coronavirus 2 (SARS CoV-2) was developed, based on a multi-target lateral flow immunoassay comprising two test lines. Both test lines bound to several classes of immunoglobulins (G, M, and A). Specific anti-SARS immunoglobulins were revealed by a colorimetric probe formed by N and gold nanoparticles. Targeting the total antibodies response to infection enabled achieving 100% diagnostic specificity (95.75–100, C.I. 95%, n = 85 healthy and with other infections individuals) and 94.6% sensitivity (84.9–98.9, C.I. 95%, n = 62 SARS CoV-2 infected subjects) as early as 7 days post confirmation of positivity. Agreeing results with a reference serological ELISA were achieved, except for the earlier detection capability of the rapid test. Follow up of the three seroconverting patients endorsed the hypothesis of the random rise of the different immunoglobulins and strengthened the 'total antibodies' approach for the trustworthy detection of serological response to SARS CoV-2 infection. Image 1 A rapid test based on the lateral flow immunoassay technology was established to detect the total serological response to the SARS CoV-2 infection. • A sensitive and specific lateral flow immunoassay for detecting antibodies to Covid-19. • Broad-specific agents to capture total immunoglobulins enabled increasing the sensitivity. • Two test lines were combined to guarantee no false positive results. • Diagnosis based on the multi-target LFIA can complement molecular assays. [ABSTRACT FROM AUTHOR]

• Reliable detection of urinary PSA was performed in 10 minutes through a new intuitive lateral flow biosensor. • The lateral flow biosensor showed a limit of detection and a range of quantification of 20 ng mL-1 and 37 – 420 ng mL-1, respectively. • The biosensor showed 92% of accuracy and an almost perfect concordance with the reference ECLIA method. • The biosensors showed acceptable precision with CV % ≤ 13% and diagnostic sensitivity, specificity, positive predictive value and negative predictive value of 100%, 64%, 74% and 100%, respectively. • The uPSA biosensor is a convenient tool to guide clinical decision-making in prostate cancer diagnosis management process. This work describes the development and the application of a lateral flow biosensor for the detection of the prostate specific antigen in urine (uPSA). The biosensor allowed uPSA detection in 10 minutes with a limit of detection and a range of quantification respectively of 20 ng mL-1 and 37 – 420 ng mL-1, showing within and between-day coefficients of variation ≤ 13%. It showed 92% of accuracy and an almost perfect concordance with the reference electrochemiluminescence immunoassay method. The biosensor design provides the disappearance of the Test line signal at the cut-off concentration. This was achieved with a double layer sensing strategy, in which gold nanoparticles were functionalized with Staphylococcal protein A – a mediator – instead of anti-PSA antibody. This strategy allow making a fine-tune on the concentration of the specific antibody, obtaining an on/off switch of the Test line at the cut-off value. The cut-off value was also established in this work, based on the distribution of uPSA levels from 140 patients, who were suspected of prostate cancer and who underwent to first biopsy. The clinical application of the biosensor to predict repeat biopsy outcome in 28 patients showed sensitivity, specificity, positive and negative predictive values of 100%, 64%, 74% and 100%, respectively. [ABSTRACT FROM AUTHOR]

• A rapid immunochromatographic strip test was developed for LMG detection. • The qualitative sensitivity for LMG detection was 2 µg/L. • The quantitative LOD was 0.28 µg/L. • The developed immunochromatographic strip test can be performed use easily with short analysis time. A rapid and simple immunochromatographic strip test assay based on competitive format was developed for leucomalachite green (LMG) detection. LMG-bovine serum albumin and rabbit anti-sheep IgG were immobilized on nitrocellulose membrane for the test line and control line, respectively. Anti-LMG-colloidal gold conjugate was immobilized onto the conjugate pad. For qualitative detection, the cut-off limit of the strip test was determined at 2 µg/L by the naked eye. For quantitative analysis, the working range of the LMG detection was 0.7–2 µg/L with LOD at 0.28 µg/L. A one-step immunochromatographic strip test for LMG detection can be completed within 5 min without any incubation, washing and blocking steps. Analysis results of LMG in aquatic animals obtained from the immunochromatographic strip test were in good agreement with those realized from enzyme-link immunosorbent assay. The developed the immunochromatographic strip test offered rapid detection as a simple (one-step), cost-effective, instrument-free assay and no need for handling reagents. [ABSTRACT FROM AUTHOR]

A rapid, portable, and semi-quantitative immunochromatographic strip was developed for rapid and visual detection of alternariol monomethyl ether (AME). For this purpose, the anti-AME monoclonal antibody (mAb) was prepared and identified. AME coupled to bovine serum albumin (BSA) via methyl 4-bromobutanoate was prepared as immunogen. The recoveries of AME in spiked cherry and orange fruits determined by competitive ELISA were 86.1% and 80.7%, respectively. A colloidal gold nanoparticle (CGN) and CGNs-mAb conjugate were synthesized, and on this basis, a competitive colloidal gold immunochromatographic strip was developed and applied to the detection of AME toxin in fruit samples. The intensity of red density of the test line (T line) is inversely proportional to AME concentration in the range 0.1-10 ng/mL. The visual limit of detection (LOD) of AME was found to be about 10 ng/mL. The semi-quantitative detection can be completed in 10 min. Moreover, the immunochromatographic strip has lower cross-reactivity with AME analogues, and it has a good stability performance (following 3 months of storage). Hence, the colloidal gold immunochromatographic strip could be used as a semi-quantitative tool for the on-site, rapid, and visual detection of AME in fruit.

A switch of viral hemagglutinin receptor binding specificity from bird-type α2,3- to human-type α2,6-linked sialic acid is necessary for an avian influenza virus to become a pandemic virus. In this study, an easy-to-use strip test to detect receptor binding specificity of influenza virus was developed. A biotinylated anti-hemagglutinin antibody that bound a broad range of group 1 influenza A viruses and latex-conjugated α2,3 (blue) and α2,6 (red) sialylglycopolymers were used in an immunochromatographic strip test, with avidin and lectin immobilized on a nitrocellulose membrane at test and control lines, respectively. Accumulation of a sialylglycopolymer-virus-antibody complex at the test line was visualized by eye. The strip test could be completed in 30min and did not require special equipment or skills, thereby avoiding some disadvantages of current methods for analyzing receptor binding specificity of influenza virus. The strip test could detect the receptor binding specificity of a wide range of influenza viruses, as well as small increases in the binding affinity of variant H5N1 viruses to α2,6 sialylglycans at viral titers >128 hemagglutination units. The strip test results were in agreement with those of ELISA virus binding assays, with correlations >0.95. In conclusion, the immunochromatographic strip test developed in this study should be useful for monitoring potential changes in the receptor binding specificity of group 1 influenza A viruses in the field., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Among shrimp viral pathogens, white spot syndrome virus (WSSV) and yellow head virus (YHV) are the most lethal agents, causing serious problems for both the whiteleg shrimp, Penaeus (Litopenaeus) vannamei, and the black tiger shrimp, Penaeus (Penaeus) monodon. Another important virus that infects P. vannamei is infectious myonecrosis virus (IMNV), which induces the white discoloration of affected muscle. In the cases of taura syndrome virus and Penaeus stylirostris densovirus (PstDNV; formerly known as infectious hypodermal and hematopoietic necrosis virus), their impacts were greatly diminished after the introduction of tolerant stocks of P. vannamei. Less important viruses are Penaeus monodon densovirus (PmDNV; formerly called hepatopancreatic parvovirus), and Penaeus monodon nucleopolyhedrovirus (PemoNPV; previously called monodon baculovirus). For freshwater prawn, Macrobrachium rosenbergii nodavirus and extra small virus are considered important viral pathogens. Monoclonal antibodies (MAbs) specific to the shrimp viruses described above have been generated and used as an alternative tool in various immunoassays such as enzyme-linked immunosorbent assay, dot blotting, Western blotting and immunohistochemistry. Some of these MAbs were further developed into immunochromatographic strip tests for the detection of WSSV, YHV, IMNV and PemoNPV and into a dual strip test for the simultaneous detection of WSSV/YHV. The strip test has the advantages of speed, as the result can be obtained within 15 min, and simplicity, as laboratory equipment and specialized skills are not required. Therefore, strip tests can be used by shrimp farmers for the pond-side monitoring of viral infection.