Diagnostic performance of a novel antigen-capture ELISA for the detection of SARS-CoV-2

Development of an enzymatic aptasensor for monitoring recombinant His-tagged proteins in microbial biotechnology

The utilization of polyhistidine tags (His-tag) for the purification and analysis of recombinant proteins is a widely adopted technique in biotechnology. Considering the high costs associated with antibody-based methods, the development of cost-effective techniques for protein identification following purification could significantly lower research expenses. This study developed a novel His-tag aptasensor, combining an anti-His tag aptamer with a G-quadruplex-based DNAzyme, which demonstrates limits of detection (LODs) of 0.29 μM and 0.73 μM for a His-tagged protein in calorimetric and point-of-care assays, respectively. These LODs are significantly lower than typical protein concentrations obtained through Ni-NTA affinity chromatography, indicating that the His-tag aptasensor provides an efficient solution for in vitro analysis and post-purification monitoring of His-tagged proteins.

Dual-Mode Immunosensor for Antibody Detection: Harnessing the Versatility of Antibody-Based Nanozymes across Optical and Electrochemical Platforms

In the early years of the 21st century, numerous viral infectious diseases have proliferated, prompting intensified efforts to devise more effective diagnostic methods. In response, various biosensors have emerged with the aim of overcoming the constraints of conventional diagnostic techniques. Nanomaterial-based biosensors have revolutionized conventional approaches, significantly enhancing biosensor performance and effectively tackling these challenges. A diverse array of nanoparticles and nanomaterials has been systematically synthesized, engineered, and employed to augment the functionalities of biosensors. This work capitalizes on the properties of gold-platinum bimetallic nanoclusters (NCs) embedded in the structure of an immunoglobulin (IgG) (Au/Pt NCs-IgG), unveiling a novel double strategy for the detection of antibodies that leverages both their catalytic NC scaffold and the biorecognition element. The detection mechanism revealed the unique oxidase-like properties of Au/Pt NCs-IgG. This distinctive property, in addition to previously reported peroxidase-like activity, positions Au/Pt NCs-IgG as an effective probe in both optical and electrochemical sandwich enzyme-linked immunosorbent assays, facilitating their incorporation in different sensor frameworks and their utilization across various applications. As a study case, anti-SARS-CoV-2 antibodies (anti-RBD IgG antibodies) were employed as the target analyte. A linear detection range was found between 0.5 and 100 ng/mL for optical immunosensors and 50-300 ng/mL for electrochemical immunosensors. The validation of the immunosensor in clinical samples demonstrated its promising diagnostic value. The significantly differential signal obtained between positive and negative clinical samples underscores the suitability of both sensors for point-of-care diagnostic applications.

Extracellular Vesicles as Biomarkers in Infectious Diseases

Extracellular vesicles (EVs) are nanosized vesicles that are secreted by all cells into the extracellular space. EVs are involved in cell-to-cell communication and can be found in different bodily fluids (bronchoalveolar lavage fluid, sputum, and urine), tissues, and in circulation; the composition of EVs reflects the physiological condition of the releasing cell. The ability to use EVs from bodily fluids for minimally invasive detection to monitor diseases makes them an attractive target. EVs carry a snapshot of the releasing cell's internal state, and they can serve as powerful biomarkers for diagnosing diseases. EVs also play a role in the body's immune and pathogen detection responses. Pathogens, such as bacteria and viruses, can exploit EVs to enhance their survival and spread and to evade detection by the immune system. Changes in the number or contents of EVs can signal the presence of an infection, offering a potential avenue for developing new diagnostic methods for infectious diseases. Ongoing research in this area aims to address current challenges and the potential of EVs as biomarkers in diagnosing a range of diseases, including infections and infectious diseases. There is limited literature on the development of EVs as diagnostic biomarkers for infectious diseases using existing molecular biology approaches. We aim to address this gap by reviewing recent EV-related investigations in infectious disease studies.

Comprehensive Review of COVID-19: Epidemiology, Pathogenesis, Advancement in Diagnostic and Detection Techniques, and Post-Pandemic Treatment Strategies

At present, COVID-19 remains a public health concern due to the ongoing evolution of SARS-CoV-2 and its prevalence in particular countries. This paper provides an updated overview of the epidemiology and pathogenesis of COVID-19, with a focus on the emergence of SARS-CoV-2 variants and the phenomenon known as 'long COVID'. Meanwhile, diagnostic and detection advances will be mentioned. Though many inventions have been made to combat the COVID-19 pandemic, some outstanding ones include multiplex RT-PCR, which can be used for accurate diagnosis of SARS-CoV-2 infection. ELISA-based antigen tests also appear to be potential diagnostic tools to be available in the future. This paper also discusses current treatments, vaccination strategies, as well as emerging cell-based therapies for SARS-CoV-2 infection. The ongoing evolution of SARS-CoV-2 underscores the necessity for us to continuously update scientific understanding and treatments for it.

Designing and expression of novel recombinant fusion protein for efficient antigen screening of SARS-CoV-2

Corona virus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), claimed millions globally. After the report of the first incidence of the virus, variants emerged with each posing a unique threat than its predecessors. Though many advanced diagnostic assays like real-time PCR are available for screening of SARS-CoV-2, their applications are being hindered because of accessibility and cost. With the advent of rapid assays for antigenic screening of SARS-CoV-2 made diagnostics far easy as the assays are rapid, cost-effective and can be used at point-of-care settings. In the present study, a fusion construct was made utilising highly immunogenic B cell epitopes from the three important structural proteins of SARS-CoV-2. The protein was expressed; purified capture mAbs generated and rapid antigen assay was developed. Eight hundred and forty nasopharyngeal swab samples were screened for the evaluation of the developed assay which showed 37.14% positivity, 96.51% and 100% sensitivity and specificity respectively. The assay developed was supposed to identify SARS-CoV-2 wild-type as well as variants of concern and variants of importance in real-time conditions.

Diagnosing arthropod-borne flaviviruses: non-structural protein 1 (NS1) as a biomarker

In recent decades, the presence of flaviviruses of concern for human health in Europe has drastically increased,exacerbated by the effects of climate change - which has allowed the vectors of these viruses to expand into new territories. Co-circulation of West Nile virus (WNV), Usutu virus (USUV), and tick-borne encephalitis virus (TBEV) represents a threat to the European continent, and this is further complicated by the difficulty of obtaining an early and discriminating diagnosis of infection. Moreover, the possibility of introducing non-endemic pathogens, such as Japanese encephalitis virus (JEV), further complicates accurate diagnosis. Current flavivirus diagnosis is based mainly on RT-PCR and detection of virus-specific antibodies. Yet, both techniques suffer from limitations, and the development of new assays that can provide an early, rapid, low-cost, and discriminating diagnosis of viral infection is warranted. In the pursuit of ideal diagnostic assays, flavivirus non-structural protein 1 (NS1) serves as an excellent target for developing diagnostic assays based on both the antigen itself and the antibodies produced against it. This review describes the potential of such NS1-based diagnostic methods, focusing on the application of flaviviruses that co-circulate in Europe.

Development of a one-step reverse transcription-quantitative polymerase chain reaction assay for the detection of porcine reproductive and respiratory syndrome virus

Porcine reproductive and respiratory syndrome (PRRS) caused by PRRS virus (PRRSV) is an important disease that severely affects the swine industry and, therefore, warrants rapid and accurate diagnosis for its control. Despite the progress in developing diagnostic tools, including polymerase chain reaction (PCR)-based methods such as reverse transcription quantitative PCR (RT-qPCR) to diagnose PRRSV infection, its diagnosis at the genetic level is challenging because of its high genetic variability. Nevertheless, RT-qPCR is the easiest and fastest method for diagnosing PRRSV. Therefore, this study aimed to develop an RT-qPCR assay for rapid and accurate diagnosis of PRRSV by encompassing all publicly available PRRSV sequences. The developed assay using highly specific primers and probes could detect up to 10 copies of PRRSV-1 and -2 subtypes. Furthermore, a comparison of the performance of the developed assay with those of two commercial kits widely used in South Korea demonstrated the higher efficiency of the developed assay in detecting PRRSV infections in field samples. For PRRSV-1 detection, the developed assay showed a diagnostic agreement of 97.7% with the results of ORF5 sequencing, while for commercial kits, it showed 95.3% and 72.1% agreement. For PRRSV-2, the developed assay showed a diagnostic agreement of 97.7%, whereas the commercial kits showed 93% and 90.7% agreement. In conclusion, we developed an assay with higher accuracy than those of the tested commercial kits, which will contribute markedly to global PRRSV control.

An update on lateral flow immunoassay for the rapid detection of SARS-CoV-2 antibodies

Over the last three years, after the outbreak of the COVID-19 pandemic, an unprecedented number of novel diagnostic tests have been developed. Assays to evaluate the immune response to SARS-CoV-2 have been widely considered as part of the control strategy. The lateral flow immunoassay (LFIA), to detect both IgM and IgG against SARS-CoV-2, has been widely studied as a point-of-care (POC) test. Compared to laboratory tests, LFIAs are faster, cheaper and user-friendly, thus available also in areas with low economic resources. Soon after the onset of the pandemic, numerous kits for rapid antibody detection were put on the market with an emergency use authorization. However, since then, scientists have tried to better define the accuracy of these tests and their usefulness in different contexts. In fact, while during the first phase of the pandemic LFIAs for antibody detection were auxiliary to molecular tests for the diagnosis of COVID-19, successively these tests became a tool of seroprevalence surveillance to address infection control policies. When in 2021 a massive vaccination campaign was implemented worldwide, the interest in LFIA reemerged due to the need to establish the extent and the longevity of immunization in the vaccinated population and to establish priorities to guide health policies in low-income countries with limited access to vaccines. Here, we summarize the accuracy, the advantages and limits of LFIAs as POC tests for antibody detection, highlighting the efforts that have been made to improve this technology over the last few years.