Overlooked benefits of using polyclonal antibodies

Current development of severe acute respiratory syndrome coronavirus 2 neutralizing antibodies (Review)

The coronavirus disease 2019 pandemic due to severe acute respiratory syndrome coronavirus 2 (SARS‑CoV‑2) seriously affected global public health security. Studies on vaccines, neutralizing antibodies (NAbs) and small molecule antiviral drugs are currently ongoing. In particular, NAbs have emerged as promising therapeutic agents due to their well‑defined mechanism, high specificity, superior safety profile, ease of large‑scale production and simultaneous application for both prevention and treatment of viral infection. Numerous NAb therapeutics have entered the clinical research stages, demonstrating promising therapeutic and preventive effects. These agents have been used for outbreak prevention and control under urgent authorization processes. The present review summarizes the molecular targets of SARS‑CoV‑2‑associated NAbs and screening and identification techniques for NAb development. Moreover, the current shortcomings and challenges that persist with the use of NAbs are discussed. The aim of the present review is to offer a reference for the development of NAbs for any future emergent infectious diseases, including SARS‑CoV‑2.

Serological and Molecular Detection of Citrus Tristeza Virus: A Review

Citrus tristeza virus (CTV) is a globally pervasive and economically significant virus that negatively impacts citrus trees, leading to substantial reductions in fruit yield. CTV occurs within the phloem of infected plants, causing a range of disease phenotypes, such as stem pitting (SP), quick decline (QD), and other detrimental diseases. Research on CTV is challenging due to the large size of its RNA genome and the diversity of CTV populations. Comparative genomic analyses have uncovered genetic diversity in multiple regions of CTV isolates' genomes, facilitating the classification of the virus into distinct genotypes. Despite these challenges, notable advancements have been made in identifying and controlling CTV strains through serological and molecular methods. The following review concentrates on the techniques of nucleic acid identification and serological analysis for various CTV isolates, assisting in the comparison and evaluation of various detection methods, which are crucial for the effective management of CTV diseases, and so contributes to the innovation and development of CTV detection methods.

A high throughput immuno-affinity mass spectrometry method for detection and quantitation of SARS-CoV-2 nucleoprotein in human saliva and its comparison with RT-PCR, RT-LAMP, and lateral flow rapid antigen test

OBJECTIVES

Many reverse transcription polymerase chain reaction (RT-PCR) methods exist that can detect SARS-CoV-2 RNA in different matrices. RT-PCR is highly sensitive, although viral RNA may be detected long after active infection has taken place. SARS-CoV-2 proteins have shorter detection windows hence their detection might be more meaningful. Given salivary droplets represent a main source of transmission, we explored the detection of viral RNA and protein using four different detection platforms including SISCAPA peptide immunoaffinity liquid chromatography-mass spectrometry (SISCAPA-LC-MS) using polyclonal capture antibodies.

METHODS

The SISCAPA-LC MS method was compared to RT-PCR, RT-loop-mediated isothermal amplification (RT-LAMP), and a lateral flow rapid antigen test (RAT) for the detection of virus material in the drool saliva of 102 patients hospitalised after infection with SARS-CoV-2. Cycle thresholds (Ct) of RT-PCR (E gene) were compared to RT-LAMP time-to-positive (TTP) (NE and Orf1a genes), RAT optical densitometry measurements (test line/control line ratio) and to SISCAPA-LC-MS for measurements of viral protein.

RESULTS

SISCAPA-LC-MS showed low sensitivity (37.7 %) but high specificity (89.8 %). RAT showed lower sensitivity (24.5 %) and high specificity (100 %). RT-LAMP had high sensitivity (83.0 %) and specificity (100.0 %). At high initial viral RNA loads (<20 Ct), results obtained using SISCAPA-LC-MS correlated with RT-PCR (R2 0.57, p-value 0.002).

CONCLUSIONS

Detection of SARS-CoV-2 nucleoprotein in saliva was less frequent than the detection of viral RNA. The SISCAPA-LC-MS method allowed processing of multiple samples in <150 min and was scalable, enabling high throughput.

Antibody mimetics: The next generation antibody engineering, a retrospective and prospective analysis

Antibody mimetics represent the fourth generation of antibody engineering, following polyclonal antibodies, monoclonal antibodies, and genetically engineered antibody fragments. Despite cumulative studies highlighting the advantages of antibody mimetics, including enhanced recognition properties, superior affinity, stability, penetrability, and cost-effectiveness, a comprehensive review of this evolving field is notably absent. In this study, spanning 1986-2023 and analyzing 24,318 publications, we undertake a retrospective and prospective analysis to elucidate the evolution roadmap of antibody mimetics, providing insights into the current landscape, global contributions, and future trajectories. Concurrently, our aim is to establish standardized terminology and delineate the research scope within the realm of antibody mimetics. These endeavors not only chart the trajectory and scope of antibody mimetics research but also underscore its potential to revolutionize medicine, technology, and science.

Sandwich ELISA for the Quantification of Nucleocapsid Protein of SARS-CoV-2 Based on Polyclonal Antibodies from Two Different Species

In this study, a cost-effective sandwich ELISA test, based on polyclonal antibodies, for routine quantification SARS-CoV-2 nucleocapsid (N) protein was developed. The recombinant N protein was produced and used for the production of mice and rabbit antisera. Polyclonal N protein-specific antibodies served as capture and detection antibodies. The prototype ELISA has LOD 0.93 ng/mL and LOQ 5.3 ng/mL, with a linear range of 1.52-48.83 ng/mL. N protein heat pretreatment (56 °C, 1 h) decreased, while pretreatment with 1% Triton X-100 increased analytical ELISA sensitivity. The diagnostic specificity of ELISA was 100% (95% CI, 91.19-100.00%) and sensitivity was 52.94% (95% CI, 35.13-70.22%) compared to rtRT-PCR (Ct < 40). Profoundly higher sensitivity was obtained using patient samples mostly containing Wuhan-similar variants (Wuhan, alpha, and delta), 62.50% (95% CI, 40.59 to 81.20%), in comparison to samples mostly containing Wuhan-distant variants (Omicron) 30.00% (6.67-65.25%). The developed product has relatively high diagnostic sensitivity in relation to its analytical sensitivity due to the usage of polyclonal antibodies from two species, providing a wide repertoire of antibodies against multiple N protein epitopes. Moreover, the fast, simple, and inexpensive production of polyclonal antibodies, as the most expensive assay components, would result in affordable antigen tests.

A Sensitive and Specific Monoclonal Antibody Based Enzyme-Linked Immunosorbent Assay for the Rapid Detection of Pretilachlor in Grains and the Environment

Pretilachlor is a chloroacetamide herbicide mainly used for weed and broadleaf weed control in rice, that is widely utilized in China. In order to detect the residue of pretilachlor in the environment and food, a highly sensitive and specific monoclonal antibody (mAb) against pretilachlor was prepared, and the half maximum inhibitory concentration (IC50) of the monoclonal antibody was validated to be 31.47 ± 2.35 μg/L. An indirect competitive ELISA (ic-ELISA) based on the antibody with a linear range of 6.25~100 μg/L was developed. The specificity of the antibody was explained by computer simulations and experimental validation. The mAb exhibited negligible cross-reactivity towards alachlor, acetochlor, propisochlor, butachlor, and metalaxyl, and the limits of detection (LOD) for pretilachlor in lake, rice, and soil samples were 4.83~5.23 μg/L. The recoveries of all samples were 78.3~91.3%. The reliability of the ic-ELISA method for residue detection of pretilachlor in the environment and grains was confirmed using high performance liquid chromatography.

High-density Au nanoshells assembled onto Fe3O4 nanoclusters for integrated enrichment and photothermal/colorimetric dual-mode detection of SARS-CoV-2 nucleocapsid protein

Traditional lateral flow immunoassays (LFIA) suffer from insufficient sensitivity, difficulty for quantitation, and susceptibility to complex substrates, limiting their practical application. Herein, we developed a polyethylenimine (PEI)-mediated approach for assembling high-density Au nanoshells onto Fe3O4 nanoclusters (MagAushell) as LFIA labels for integrated enrichment and photothermal/colorimetric dual-mode detection of SARS-CoV-2 nucleocapsid protein (N protein). PEI layer served not only as "binders" to Fe3O4 nanoclusters and Au nanoshells, but also "barriers" to ambient environment. Thus, MagAushell not only combined magnetic and photothermal properties, but also showed good stability. With MagAushell, N protein was first separated and enriched from complex samples, and then loaded to the strip for detection. By observation of the color stripes, qualitative detection was performed with naked eye, and by measuring the temperature change under laser irradiation, quantification was attained free of sophisticated instruments. The introduction of Fe3O4 nanoclusters facilitated target purification and enrichment before LFIA, which greatly improved the anti-interference ability and increased the detection sensitivity by 2 orders compared with those without enrichment. Moreover, the high loading density of Au nanoshells on one Fe3O4 nanocluster enhanced the photothermal signal of the nanoprobe significantly, which could further increase the detection sensitivity. The photothermal detection limit reached 43.64 pg/mL which was 1000 times lower than colloidal gold strips. Moreover, this method was successfully applied to real samples, showing great application potential in practice. We envision that this LFIA could serve not only for SARS-CoV-2 detection but also as a general test platform for other biotargets in clinical samples.

Enhanced Stability Differentiation of Therapeutic Polyclonal Antibodies with All Ion Unfolding-Ion Mobility-Mass Spectrometry

Compared with monoclonal antibodies, polyclonal antibodies (pAbs) have rather significant characteristics, including lower cost, shorter production cycle, and higher affinity. Therefore, to facilitate their applications in clinic, it is equally critical to comprehensively characterize the conformational stabilities of pAb at the molecular weight-resolved scale, which is technically challenging due to the lack of an effective analytical tool capable of simultaneously providing both stability and molecular weight information within an acceptable error range. Ion mobility-mass spectrometry (IM-MS) has grown as an alternative to rapidly assess protein conformational stability with accurate molecular weight information maintained, especially when equipped with a collision-induced unfolding (CIU) regime. Dynamic and transient conformational intermediates can be captured with the CIU-IM-MS technique, adding to traditional static structural measurements with collisional cross section. Most CIU-IM-MS-centered protocols are focusing on the application to isolated, targeted protein ions, namely, analyzing one single charge state at one time, limiting its analytical throughput and speed. In this study, we employed an enhanced unfolding regime, all ion unfolding (AIU), capable of the simultaneous operation of numerous ions at a time during stepped unfolding processes to analyze pAb. Results show that AIU can quantitatively characterize the subtle differences in conformational stability among four structurally similar pAbs with improved resolving capability by around a 2-4-fold increment in both stability and structure differentiating parameters. Besides, AIU also benefits from considerably saved time cost and improved spectrum quality with an elevated signal-to-noise ratio.

A Proof-of-Concept Sandwich Enzyme-Linked Immunoassay Development for Small Molecules

A sandwich immunoassay theoretically exhibits higher sensitivity and specificity compared to a competitive counterpart; however, it is extremely difficult to obtain a pair of antibodies that can bind to a small molecule simultaneously, which is always thought to be a single epitope. In the present study, abamectin (ABM) was selected to prove the effect of hapten design and antibody recognition properties on the development of a sandwich immunoassay for small molecules. First, the epitopes of ABM were roughly located, and epitope distances were determined. Then, two haptens were designed by introducing spacer arms at the C4″-OH and C5-OH of ABM, respectively, aiming to provide the longest epitope distances. A total of seven rabbit polyclonal antibodies (pAbs) and 21 mouse monoclonal antibodies (mAbs) with various recognition properties were obtained. Extensive combinatorial associations of antibody pairs for simultaneously binding to ABM were performed, and only two mAb-mAb pairs were observed to achieve a sandwich immunoassay for ABM with a total success rate of 0.27%. The best mAb pair for sandwich immunoassay was confirmed by surface plasmon resonance, used to develop a sandwich immunoassay, and then evaluated by cross-reactivities and molecular docking with structurally similar analogues and abamectin. Altogether, the study provided a theoretical foundation as well as practical experience and demonstrated the importance of careful hapten design and extensive antibody screening to successfully establish the sandwich immunoassay for small molecules.

Potential of an anti-bevacizumab idiotype scFv DNA-based immunization to elicit VEGF-binding antibody response

Anti-idiotype antibodies have been considered for vaccination approaches against different diseases, including cancers. Based on that, we previously described an anti-bevacizumab idiotype monoclonal antibody, 10.D7, that revealed detectable antitumor effects on a vascular endothelial growth factor (VEGF)-dependent tumor model. Herein, we evaluated the possible applicability of a single-chain variable fragment (scFv) for the 10.D7 antibody in a gene immunization strategy. After checking that mammalian cells transfected to express the 10.D7 scFv are recognized by bevacizumab, it was explored the ability of our scFv construction, in a gene-based scheme, to elicit an immune response containing VEGF-binding antibodies. The results provide evidence that the designed 10.D7 scFv construct maintains the anti-bevacizumab idiotype features and has potential to activate an immune response recognizing VEGF.

Longitudinal Evaluation of AFP and CEA External Proficiency Testing Reveals Need for Method Harmonization

The glycoproteins alpha-fetoprotein (AFP) and carcinoembryonic antigen (CEA) have long been approved as biomarkers for diagnosing and monitoring tumors. International Reference Preparations (IRPs) have been around since 1975. Nevertheless, manufacturer-dependent differences have been reported, indicating a lack of harmonization. This paper analyzes data from 15 external quality assessment (EQA) surveys conducted worldwide between 2018 and 2022. The aim was to gain insight into the longitudinal development of manufacturer-dependent differences for CEA and AFP. In each survey, participating laboratories received two samples with different tumor marker levels. Inter- and intra-assay variability was analyzed and the mean 80% and 90% of the manufacturer collectives were compared to the evaluation criteria of the German Medical Association (RiliBÄK). The median EQA results for CEA revealed manufacturer-dependent differences between the highest and lowest collective of up to 100%; for AFP, the median differences mostly remained below 40%. The coefficients of variation were predominantly low for both markers. We concluded that the current assays for AFP and CEA detection are better harmonized than previously reported. The assays displayed a good robustness; however, a narrowing of the current assessment limits in EQA schemes could further enhance the quality of laboratory testing.

Nano magnetic-based ELISA and nano magnetic-based latex agglutination test for diagnosis of experimental trichinellosis

Human trichinellosis is a worldwide foodborne public health threat. Detecting circulating antigens of Trichinella spiralis "T. spiralis" allows for an early diagnosis before larval encystation develops in skeletal muscles. For the first time, the present study aimed to formulate an effective nanomagnetic beads based-ELISA and -latex agglutination test (NMB-ELISA and NMB-LAT) to recognize T. spiralis adult worm crude extract antigen (AWCEA) in sera of experimentally infected mice. The study included thirty-eight mice classified into 3 groups; T. spiralis-infected group (GI) which was euthanized 6, 8, 10, 12, 14 days post-infection (dpi), other parasitic infections group (GII) and healthy control group (GIII). Rabbit anti-T. spiralis polyclonal antibodies (pAbs) were utilized to detect AWCEA in serum samples by sandwich ELISA, NMB-ELISA, and NMB-LAT. Using NMB-ELISA, AWCEA was detected in sera collected at 6 and 8 dpi, with a sensitivity of 50% and 75%, respectively, and a specificity of 100%. Whereas, sandwich ELISA and NMB-LAT couldn't detect the antigen at the same time intervals. Both ELISA formats were able to detect the antigen in samples collected at 10, 12, and 14 dpi with a sensitivity of 100% for NMB-ELISA and 25%, 75%, and 100% respectively, for sandwich-ELISA. Yet, NMB-LAT couldn't detect AWCEA until 12 dpi with a sensitivity of 50% and specificity of 75%. In conclusion, NMB-ELISA is a promising sensitive tool for early and specific diagnosis of acute trichinellosis. The use of NMB-LAT could be a helpful screening procedure in field surveys.

Current and emerging trends in techniques for plant pathogen detection

Plant pathogenic microorganisms cause substantial yield losses in several economically important crops, resulting in economic and social adversity. The spread of such plant pathogens and the emergence of new diseases is facilitated by human practices such as monoculture farming and global trade. Therefore, the early detection and identification of pathogens is of utmost importance to reduce the associated agricultural losses. In this review, techniques that are currently available to detect plant pathogens are discussed, including culture-based, PCR-based, sequencing-based, and immunology-based techniques. Their working principles are explained, followed by an overview of the main advantages and disadvantages, and examples of their use in plant pathogen detection. In addition to the more conventional and commonly used techniques, we also point to some recent evolutions in the field of plant pathogen detection. The potential use of point-of-care devices, including biosensors, have gained in popularity. These devices can provide fast analysis, are easy to use, and most importantly can be used for on-site diagnosis, allowing the farmers to take rapid disease management decisions.

Preparation of polyclonal antibody against a universal bacterial antigen OmpA deduced by bioinformatic analysis and preliminary evaluation of concentration effects on foodborne pathogens

Rapid and ultrasensitive microbial detection in actual samples have challenges because of target pathogen diversity and low abundance. In this study, we attempted to capture and concentrate multiple pathogens by combining magnetic beads with polyclonal antibodies against a universal antigen of ompA, LAMOA-1, before further detection. A protein sequence consisting of 241 amino acids with spatial conformation similar to E. coli ompA was identified and expressed as a recombinant protein in prokaryotes according to the results of sequence alignment among 432 sequences of ompA belonging to intestinal bacteria from gram-negative bacteria. Purified from immunized rabbits, the anti-LAMOA-1 antibody was shown to effectively recognize 12 foodborne bacterial species. Antibody-conjugated beads were used to concentrate the bacteria when the bacterial concentration in artificially contaminated samples is between 10 and 100 CFU/mL, which shortens detection duration by 8-24 h. The enrichment strategy is potentially beneficial for detection of foodborne pathogens.

Capture ELISA for KPC Detection in Gram-Negative Bacilli: Development and Standardisation

The detection of KPC-type carbapenemases is necessary for guiding appropriate antibiotic therapy and the implementation of antimicrobial stewardship and infection control measures. Currently, few tests are capable of differentiating carbapenemase types, restricting the lab reports to their presence or not. The aim of this work was to raise antibodies and develop an ELISA test to detect KPC-2 and its D179 mutants. The ELISA-KPC test was designed using rabbit and mouse polyclonal antibodies. Four different protocols were tested to select the bacterial inoculum with the highest sensitivity and specificity rates. The standardisation procedure was performed using 109 previously characterised clinical isolates, showing 100% of sensitivity and 89% of specificity. The ELISA-KPC detected all isolates producing carbapenemases, including KPC variants displaying the ESBL phenotype such as KPC-33 and -66.

Enhanced in vivo anti-tumor efficacy of whole tumor lysate in combination with whole tumor cell-specific polyclonal antibody

Background and purpose

Despite the widespread utilization of cancer vaccines with specified antigens, the use of whole tumor cell lysates in tumor immunotherapy would be a very promising approach that can overcome several significant obstacles in vaccine production. Whole tumor cells provide a broad source of tumor-associated antigens and can activate cytotoxic T lymphocytes and CD4+ T helper cells concurrently. On the other hand, as an effective immunotherapy strategy, recent investigations have shown that the multi-targeting of tumor cells with polyclonal antibodies, which are also more effective than monoclonal antibodies at mediating effector functions for target elimination, might minimize the escape variants.

Experimental approach

We prepared polyclonal antibodies by immunizing rabbits with the highly invasive 4T1 breast cancer cell line.

Findings/Results

In vitro investigation indicated that the immunized rabbit serum inhibited cell proliferation and induced apoptosis in target tumor cells. Moreover, in vivo analysis showed enhanced anti-tumor efficacy of whole tumor cell lysate in combination with tumor cell-immunized serum. This combination therapy proved beneficial in significant inhibition of the tumor growth and the established tumor was entirely eradicated in treated mice.

Conclusion and implications

Serial intravenous injections of tumor cell immunized rabbit serum significantly inhibited tumor cell proliferation and induced apoptosis in vitro and in vivo in combination with whole tumor lysate. This platform could be a promising method for developing clinical-grade vaccines and open up the possibility of addressing the effectiveness and safety of cancer vaccines.

Analytical Techniques for the Characterization and Quantification of Monoclonal Antibodies

Monoclonal antibodies (mAbs) are a fast-growing class of biopharmaceuticals. They are widely used in the identification and detection of cell makers, serum analytes, and pathogenic agents, and are remarkably used for the cure of autoimmune diseases, infectious diseases, or malignancies. The successful application of therapeutic mAbs is based on their ability to precisely interact with their appropriate target sites. The precision of mAbs rely on the isolation techniques delivering pure, consistent, stable, and safe lots that can be used for analytical, diagnostic, or therapeutic applications. During the creation of a biologic, the key quality features of a particular mAb, such as structure, post-translational modifications, and activities at the biomolecular and cellular levels, must be characterized and profiled in great detail. This implies the requirement of powerful state of the art analytical techniques for quality control and characterization of mAbs. Until now, various analytical techniques have been developed to characterize and quantify the mAbs according to the regulatory guidelines. The present review summarizes the major techniques used for the analyses of mAbs which include chromatographic, electrophoretic, spectroscopic, and electrochemical methods in addition to the modifications in these methods for improving the quality of mAbs. This compilation of major analytical techniques will help students and researchers to have an overview of the methodologies employed by the biopharmaceutical industry for structural characterization of mAbs for eventual release of therapeutics in the drug market.

Resolving Molecular Heterogeneity with Single-Molecule Centrifugation

For many classes of biomolecules, population-level heterogeneity is an essential aspect of biological function─from antibodies produced by the immune system to post-translationally modified proteins that regulate cellular processes. However, heterogeneity is difficult to fully characterize for multiple reasons: (i) single-molecule approaches are needed to avoid information lost by ensemble-level averaging, (ii) sufficient statistics must be gathered on both a per-molecule and per-population level, and (iii) a suitable analysis framework is required to make sense of a potentially limited number of intrinsically noisy measurements. Here, we introduce an approach that overcomes these difficulties by combining three techniques: a DNA nanoswitch construct to repeatedly interrogate the same molecule, a benchtop centrifuge force microscope (CFM) to obtain thousands of statistics in a highly parallel manner, and a Bayesian nonparametric (BNP) inference method to resolve separate subpopulations with distinct kinetics. We apply this approach to characterize commercially available antibodies and find that polyclonal antibody from rabbit serum is well-modeled by a mixture of three subpopulations. Our results show how combining a spatially and temporally multiplexed nanoswitch-CFM assay with BNP analysis can help resolve complex biomolecular interactions in heterogeneous samples.

Immune Checkpoint Glycoproteins Have Polymorphism: Are Monoclonal Antibodies Too Specific?

Since the 2018 Nobel prize in medicine was granted to the discovery of immune escape by cancer cells, billions of dollars have been spent on a new form of cancer immunotherapy called immune checkpoint inhibition (ICI). In this treatment modality, monoclonal antibodies (mAbs) are used to block cell-surface glycoproteins responsible for cancer immune escape. However, only a subset of patients benefit from this treatment. In this commentary, we focus on the polymorphism in the target molecules of these mAbs, namely PD-1, PD-L1 and CTLA4; we explain that using a single mAb from one clone is unlikely to succeed in treating all humans because humans have a genotype and phenotype polymorphism in these molecules. Monoclonal antibodies are highly specific and are capable of recognizing only one epitope ("monospecific"), which makes them ideal for use in laboratory animals because these animals are generationally inbred and genetically identical (isogenic). In humans, however, the encoding genes for PD-1, PD-L1 and CTLA4 have variations (alleles), and the final protein products have phenotype polymorphism. This means that small differences exist in these proteins among individual humans, rendering one mAb too specific to cover all patients. Our suggestion for the next step in advancing this oncotherapy is to focus on methods to tailor the mAb treatment individually for each patient or replace a single clone of mAb with less specific alternatives, e.g., a "cocktail of mAbs", oligoclonal antibodies or recombinant polyclonal antibodies. Fortunately, there are ongoing clinical trials on oligoclonal antibodies at the moment.

The agony of choice: Impact of the host animal species on the enzyme-linked immunosorbent assay performance for host cell protein quantification

Host cell proteins (HCPs) are inevitable process-related impurities in biotherapeutics commonly monitored by enzyme-linked immunosorbent assays (ELISAs). Of particular importance for their reliable detection are the anti-HCP polyclonal antibodies (pAbs), supposed to detect a broad range of HCPs. The present study focuses on the identification of suitable host animal species for the development of high-performance CHO-HCP ELISAs, assuming the generation of pAbs with adequate coverage and specificity. Hence, antibodies derived from immunization of sheep, goats, donkeys, rabbits, and chickens were compared concerning their amount of HCP-specific antibodies, coverage, and performance in a sandwich ELISA. Immunization of sheep, goats, donkeys, and rabbits met all test criteria, whereas the antibodies from chickens cannot be recommended based on the results of this study. Additionally, a mixture of antibodies from the five host species was prepared to assess if coverage and ELISA performance can be improved by a multispecies approach. Comparable results were obtained for the single- and multispecies ELISAs in different in-process samples, indicating no substantial improvement for the latter in ELISA performance while raising ethical and financial concerns.

Rapid-format recombinant antibody-based methods for the diagnosis of Clostridioides difficile infection: Recent advances and perspectives

Clostridioides difficile, the most common cause of nosocomial diarrhea, has been continuously reported as a worldwide problem in healthcare settings. Additionally, the emergence of hypervirulent strains of C. difficile has always been a critical concern and led to continuous efforts to develop more accurate diagnostic methods for detection of this recalcitrant pathogen. Currently, the diagnosis of C. difficile infection (CDI) is based on clinical manifestations and laboratory tests for detecting the bacterium and/or its toxins, which exhibit varied sensitivity and specificity. In this regard, development of rapid diagnostic techniques based on antibodies has demonstrated promising results in both research and clinical environments. Recently, application of recombinant antibody (rAb) technologies like phage display has provided a faster and more cost-effective approach for antibody production. The application of rAbs for developing ultrasensitive diagnostic tools ranging from immunoassays to immunosensors, has allowed the researchers to introduce new platforms with high sensitivity and specificity. Additionally, DNA encoding antibodies are directly accessible in these approaches, which enables the application of antibody engineering to increase their sensitivity and specificity. Here, we review the latest studies about the antibody-based ultrasensitive diagnostic platforms for detection of C. difficile bacteria, with an emphasis on rAb technologies.

Importance of CAR-T cell therapy monitoring using high-throughput assays

Advances in the development of chimeric antigen receptor (CAR)-T cells have undermined the paramount importance of this technology for the success of adoptive T-cell immunotherapy. The bespoke production of autologous CAR-T cells is a lengthy and costly process. Thus, the development of more cost-effective allogeneic 'off-the-shelf' CAR-T cells provides a more readily available treatment option. The exploration of methods to reduce costs and to determine which CAR-T cells are the most effective is key for providing this breakthrough treatment to most patients. The process from the design and development of CAR-T cells, through pre-clinical and clinical testing and manufacturing, to patient monitoring involves a variety of high-throughput tools that enable the monitoring of all processes to ensure the safety and efficacy of the treatment.

Transchromosomic bovines-derived broadly neutralizing antibodies as potent biotherapeutics to counter important emerging viral pathogens with a special focus on SARS-CoV-2, MERS-CoV, Ebola, Zika, HIV-1, and influenza A virus

Historically, passive immunotherapy is an approved approach for protecting and treating humans against various diseases when other alternative therapeutic options are unavailable. Human polyclonal antibodies (hpAbs) can be made from convalescent human donor serum, although it is considered limited due to pandemics and the urgent requirement. Additionally, polyclonal antibodies (pAbs) could be generated from animals, but they may cause severe immunoreactivity and, once "humanized," may have lower neutralization efficiency. Transchromosomic bovines (TcBs) have been developed to address these concerns by creating robust neutralizing hpAbs, which are useful in preventing and/or curing human infections in response to hyperimmunization with vaccines holding adjuvants and/or immune stimulators over an extensive period. Unlike other animal-derived pAbs, potent hpAbs could be promptly produced from TcB in large amounts to assist against an outbreak scenario. Some of these highly efficacious TcB-derived antibodies have already neutralized and blocked diseases in clinical studies. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has numerous variants classified into variants of concern (VOCs), variants of interest (VOIs), and variants under monitoring. Although these variants possess different mutations, such as N501Y, E484K, K417N, K417T, L452R, T478K, and P681R, SAB-185 has shown broad neutralizing activity against VOCs, such as Alpha, Beta, Gamma, Delta, and Omicron variants, and VOIs, such as Epsilon, Iota, Kappa, and Lambda variants. This article highlights recent developments in the field of bovine-derived biotherapeutics, which are seen as a practical platform for developing safe and effective antivirals with broad activity, particularly considering emerging viral infections such as SARS-CoV-2, Ebola, Middle East respiratory syndrome coronavirus, Zika, human immunodeficiency virus type 1, and influenza A virus. Antibodies in the bovine serum or colostrum, which have been proved to be more protective than their human counterparts, are also reviewed.

Effective blocking of neuropilin-1activity using oligoclonal nanobodies targeting different epitopes

Neuropilin-1 (NRP-1) is a non-tyrosine kinase receptor and when overexpressed, leads to angiogenesis. High expression of NRP-1 has been observed in various cancers. Unique characteristic of nanobodies (small size, high affinity and stability, and ease production) make them potential therapeutic tools. Oligoclonal nanobodies which detect multiple functional epitopes on the target antigen could be potential tools for inhibition of cancer resistance problems due to escape variant of tumor cells. In this study, oligoclonal anti-NRP-1 nanobodies were selected from camel immune library and their binding activities as well as in vitro functionality were evaluated. Anti-NRP-1 nanobodies were expressed in an Escherichia coli host, and purified using nickel affinity chromatography. The effect of each individual and oligoclonal nanobodies on human endothelial cells were evaluated by MTT, Tube formation, and migration assay as well. Results showed that oligoclonal anti-NRP-1 nanobodies detected different epitopes of NRP-1 antigen and inhibited in vitro angiogenesis of human endothelial cells better than each individual nanobody. Results indicate promising oligoclonal anti-NRP-1 nanobodies for inhibition of angiogenesis.

Detergent micelle conjugates containing amino acid monomers allow purification of human IgG near neutral pH

Industrial scale production of therapeutic monoclonal antibodies (mAbs) is commonly achieved with Protein A chromatography, a process that requires exposure of the antibody to strongly acidic conditions during the eluting step. Exposure to acid inactivates virus contaminants but may, in parallel, lead to antibody aggregation that must be eliminated or kept at acceptably low levels. This report seeks to provide a practical method for overcoming a long-standing problem. We show how Brij-O20 detergent micelles, conjugated by the amphiphilic [(bathophenanthroline)₃:Fe²⁺] complex in the presence of amino acid monomers: phenylalanine (Phe), tyrosine (Tyr), tryptophan (Trp), isoleucine (Ile) or valine (Val), efficiently capture polyclonal human IgG (hIgG) at neutral pH and allow its recovery by extraction either at pH 4 (85-97% yield) or at pH 6.3 (72-84% yield). Of the five amino acid monomers surveyed, Phe or Tyr produced the highest overall process yield at both pH 4 and 6.3. The monomeric state of the purified hIgG's was confirmed by dynamic light scattering (DLS). Potential advantages of the purification method are discussed.

Evaluation of New Polyclonal Antibody Developed for Serological Diagnostics of Tomato Mosaic Virus

Plant viruses threaten agricultural production by reducing the yield, quality, and economical benefits. Tomato mosaic virus (ToMV) from the genus Tobamovirus causes serious losses in the quantity and quality of tomato production. The management of plant protection is very difficult, mainly due to the vector-less transmission of ToMV. Resistant breeding generally has low effectiveness. The most practical approach is the use of a rapid diagnostic assay of the virus' presence before the symptoms occur in plants, followed by the eradication of virus-infected plants. Such approaches also include serological detection methods (ELISA and Western immunoblotting), where antibodies need to be developed for an immunochemical reaction. The development and characterization of polyclonal antibodies for the detection of ToMV with appropriate parameters (sensitivity, specificity, and cross-reactivity) were the subjects of this study. A new polyclonal antibody, AB-1, was developed in immunized rabbits using the modified oligopeptides with antigenic potential (sequences are revealed) derived from the coat protein of ToMV SL-1. the developed polyclonal antibody. AB-1, showed higher sensitivity when compared with commercially available analogs. It also detected ToMV in infected pepper and eggplant plants, and detected another two tobamoviruses (TMV and PMMoV) and ToMV in soil rhizosphere samples and root residues, even two years after the cultivation of the infected tomato plant.

Immunohistochemical detection of enteroviruses in pancreatic tissues of patients with type 1 diabetes using a polyclonal antibody against 2A protease of Coxsackievirus

AIMS/INTRODUCTION

The need for antiserum for immunohistochemical (IHC) detection of enterovirus (EV) in formaldehyde-fixed and paraffin-embedded samples is increasing. The gold standard monoclonal antibody (clone 5D8/1) against EV-envelope protein (VP1) was proven to cross-react with other proteins. Another candidate marker of EV proteins is 2A protease (2Apro ), which is encoded by the EV gene and translated by the host cells during EV replication, and participates processing proproteins to viral capsid proteins.

MATERIALS AND METHODS

We raised polyclonal antiserum by immunizing a rabbit with an 18-mer peptide of Coxsackievirus B1 (CVB1)-2Apro , and examined the specificity and sensitivity for EV on formaldehyde-fixed and paraffin-embedded tissue samples.

RESULTS

Enzyme-linked immunosorbent assay study showed a high titer of antibody for 18-mer peptide of CVB1-2Apro , cross-reacting with CVB3-2Apro peptide. IHC showed that antiserum against 2Apro reacted with CVB1-infected and VP1-positive Vero cells. Confocal laser scanning microscopy showed that antigen stained by the 2Apro antibody located in the same cell with VP1 stained by 5D8/1. IHC using 2Apro antiserum showed dense staining in the islets of EV-associated fulminant type 1 diabetes pancreas and that located in the same cell stained positive for VP1 (5D8/1). Specificity of 2Apro antiserum by IHC staining was confirmed by negative 2Apro in 14 VP1-negative non-diabetes control pancreases.

CONCLUSIONS

Our study provides a new polyclonal antiserum against CVB1-2Apro , which might be useful for IHC of EV-infected human tissues stored as archive of formaldehyde-fixed and paraffin-embedded tissue samples.

Immunohistochemistry as a detection tool for ion channels involved in dental pain signaling

Background

Despite advances in pain detection, diagnosis, and management, the prevalence of dental pain is still on the rise. Although dental pain is not directly related to fatal outcomes, the two most common types of dental pain—dental caries and dentin hypersensitivity—have a significant impact on an individual’s quality of life. Understanding the mechanism of the pain pathway is one of the crucial steps in providing better treatment for these patients. Ion channels are critical biomolecules that have been the subject of dental study owing to their roles in the transmission and transduction of external stimuli, as well as in the control and perception of pain. Numerous immunohistochemical (IHC) staining approaches have also been used to identify the many ion channels implicated in peripheral pain signaling in dental pulp.

Highlight

This review highlights the critical steps in IHC and its role in the detection of ion channels involved in the dental pain signaling pathway.

Conclusion

The key ion channels identified using IHC and whose functions have been widely researched in dental tissues are addressed in this review article.

Genetic drift in the genome of SARS COV-2 and its global health concern

The outbreak of the current coronavirus disease (COVID-19) occurred in late 2019 and quickly spread all over the world. The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) belongs to a genetically diverse group that mutates continuously leading to the emergence of multiple variants. Although a few antiviral agents and anti-inflammatory medicines are available, thousands of individuals have passed away due to emergence of new viral variants. Thus, proper surveillance of the SARS-CoV-2 genome is needed for the rapid identification of developing mutations over time, which are of the major concern if they occur specifically in the surface spike proteins of the virus (neutralizing analyte). This article reviews the potential mutations acquired by the SARS-CoV2 since the pandemic began and their significant impact on the neutralizing efficiency of vaccines and validity of the diagnostic assays.

Potential Therapeutic Targets for Combination Antibody Therapy against Pseudomonas aeruginosa Infections

Despite advances in antimicrobial therapy and even the advent of some effective vaccines, Pseudomonas aeruginosa (P. aeruginosa) remains a significant cause of infectious disease, primarily due to antibiotic resistance. Although P. aeruginosa is commonly treatable with readily available therapeutics, these therapies are not always efficacious, particularly for certain classes of patients (e.g., cystic fibrosis (CF)) and for drug-resistant strains. Multi-drug resistant P. aeruginosa infections are listed on both the CDC’s and WHO’s list of serious worldwide threats. This increasing emergence of drug resistance and prevalence of P. aeruginosa highlights the need to identify new therapeutic strategies. Combinations of monoclonal antibodies against different targets and epitopes have demonstrated synergistic efficacy with each other as well as in combination with antimicrobial agents typically used to treat these infections. Such a strategy has reduced the ability of infectious agents to develop resistance. This manuscript details the development of potential therapeutic targets for polyclonal antibody therapies to combat the emergence of multidrug-resistant P. aeruginosa infections. In particular, potential drug targets for combinational immunotherapy against P. aeruginosa are identified to combat current and future drug resistance.

In-House Immunofluorescence Assay for Detection of SARS-CoV-2 Antigens in Cells from Nasopharyngeal Swabs as a Diagnostic Method for COVID-19

Immunofluorescence is a traditional diagnostic method for respiratory viruses, allowing rapid, simple and accurate diagnosis, with specific benefits of direct visualization of antigens-of-interest and quality assessment. This study aims to evaluate the potential of indirect immunofluorescence as an in-house diagnostic method for SARS-CoV-2 antigens from nasopharyngeal swabs (NPS). Three primary antibodies raised from mice were used for immunofluorescence staining, including monoclonal antibody against SARS-CoV nucleocapsid protein, and polyclonal antibodies against SARS-CoV-2 nucleocapsid protein and receptor-binding domain of SARS-CoV-2 spike protein. Smears of cells from NPS of 29 COVID-19 patients and 20 non-infected individuals, and cells from viral culture were stained by the three antibodies. Immunofluorescence microscopy was used to identify respiratory epithelial cells with positive signals. Polyclonal antibody against SARS-CoV-2 N protein had the highest sensitivity and specificity among the three antibodies tested, detecting 17 out of 29 RT-PCR-confirmed COVID-19 cases and demonstrating no cross-reactivity with other tested viruses except SARS-CoV. Detection of virus-infected cells targeting SARS-CoV-2 N protein allow identification of infected individuals, although accuracy is limited by sample quality and number of respiratory epithelial cells. The potential of immunofluorescence as a simple diagnostic method was demonstrated, which could be applied by incorporating antibodies targeting SARS-CoV-2 into multiplex immunofluorescence panels used clinically, such as for respiratory viruses, thus allowing additional routine testing for diagnosis and surveillance of SARS-CoV-2 even after the epidemic has ended with low prevalence of COVID-19.

Structure-Based Epitope Design: Toward a Greater Antibody-SARS-CoV-2 RBD Affinity

Efficient COVID-19 vaccines are widely acknowledged as the best way to end the global pandemic. SARS-CoV-2 receptor-binding domain (RBD) plays fundamental roles related to cell infection. Antibodies could be developed to target RBD and represent a potential approach for the neutralization of the virus. Epitopes used to produce antibodies are generally linear peptides and thus possess multiple confirmations that do not reflect the actual topology of the targeted part in the native protein. On the other hand, macrocyclic epitopes could constitute closer mimics of the native protein topology and, as such, could generate superior antibodies. In this study, we demonstrated the vital effect of the size and the three-dimensional shape of epitopes on the activity of the developed antibodies against the RBD of SARS-CoV-2. The molecular dynamics studies showed the greater stability of the cyclic epitopes compared with the linear counterparts, which was reflected in the affinity of the produced antibodies. The antibodies developed using macrocyclic epitopes showed superiority with respect to binding to RBD compared to antibodies formed from linear peptides. This study constitutes a roadmap for developing superior antibodies that could be used to inhibit the activity of SARS-CoV-2.

Toward the Development of Rapid, Specific, and Sensitive Microfluidic Sensors: A Comprehensive Device Blueprint

Recent advances in nano/microfluidics have led to the miniaturization of surface-based chemical and biochemical sensors, with applications ranging from environmental monitoring to disease diagnostics. These systems rely on the detection of analytes flowing in a liquid sample, by exploiting their innate nature to react with specific receptors immobilized on the microchannel walls. The efficiency of these systems is defined by the cumulative effect of analyte detection speed, sensitivity, and specificity. In this perspective, we provide a fresh outlook on the use of important parameters obtained from well-characterized analytical models, by connecting the mass transport and reaction limits with the experimentally attainable limits of analyte detection efficiency. Specifically, we breakdown when and how the operational (e.g., flow rates, channel geometries, mode of detection, etc.) and molecular (e.g., receptor affinity and functionality) variables can be tailored to enhance the analyte detection time, analytical specificity, and sensitivity of the system (i.e., limit of detection). Finally, we present a simple yet cohesive blueprint for the development of high-efficiency surface-based microfluidic sensors for rapid, sensitive, and specific detection of chemical and biochemical analytes, pertinent to a variety of applications.

Validation of antibodies: Lessons learned from the Common Fund Protein Capture Reagents Program

Large-scale generation of protein capture reagents remains a technical challenge, but their generation is just the beginning. Validation is a critical, iterative process that yields different results for different uses. Independent, community-based validation offers the possibility of transparent data sharing, with use case–specific results made broadly available. This type of resource, which can grow as new validation data are obtained for an expanding group of reagents, provides a community resource that should accompany future reagent-generating efforts. To address a pressing need for antibodies or other reagents that recognize human proteins, the National Institutes of Health Common Fund launched the Protein Capture Reagents Program in 2010 as a pilot to target human transcription factors. Here, we describe lessons learned from this program concerning generation and validation of research reagents, which we believe are generally applicable for future research endeavors working in a similar space.

ELISA-Based Method for Variant-Independent Detection of Total Microcystins and Nodularins via a Multi-immunogen Approach

Required routine monitoring of microcystins (MCs) and nodularins (NODs) in water samples, as posed by U.S. EPA Unregulated Contaminant Monitoring Rule 4, demands cost-effective, reliable, and sensitive detection methods. To target as many MC and NOD variants as possible, we developed an indirect competitive enzyme-linked immunosorbent assay (ELISA) with group-specific monoclonal antibodies for variant-independent detection of total MCs and NODs. In this ELISA method, the mice monoclonal antibodies presenting both high affinities and broad-spectrum recognition capabilities against MCs and NODs were self-produced by designing MC hapten-based multi-immunogens to minimize specificity for the particular variant. Their high affinities and variant-independent binding capabilities against MCs and NODs were validated by both wet lab and in silico methods. The developed ELISA method achieved a limit of detection of below 0.3 μg/L for 13 MC/NOD variants, well with the reported best cross-reactivities of 60-127% relative to MC-LR. As a case study, this ELISA method was used to map the variations of intracellular and extracellular total MCs/NODs in the Luoma Lake drinking water source, China, in July, 2020. Its capability to measure total MCs/NODs with high sensitivity and high throughput in a simple and affordable way would truly be a disruptive technology capable of changing our understanding of bloom/toxin dynamics and having obvious implications for monitoring efforts.

IgY technology: Methods for developing and evaluating avian immunoglobulins for the in vitro detection of biomolecules

The term “IgY technology” was introduced in the literature in the mid 1990s to describe a procedure involving immunization of avian species, mainly laying hens and consequent isolation of the polyclonal IgYs from the “immune” egg yolk (thus avoiding bleeding and animal stress). IgYs have been applied to various fields of medicine and biotechnology. The present article will deal with specific aspects of IgY technology, focusing on the currently reported methods for developing, isolating, evaluating and storing polyclonal IgYs. Other topics such as current information on isolation protocols or evaluation of IgYs from different avian species are also discussed. Specific advantages of IgY technology (e.g., novel antibody specificities that may emerge via the avian immune system) will also be discussed. Recent in vitro applications of polyclonal egg yolk-derived IgYs to the field of disease diagnosis in human and veterinary medicine through in vitro immunodetection of target biomolecules will be presented. Moreover, ethical aspects associated with animal well-being as well as new promising approaches that are relevant to the original IgY technology (e.g., development of monoclonal IgYs and IgY-like antibodies through the phage display technique or in transgenic chickens) and future prospects in the area will also be mentioned.

Proteomes Are of Proteoforms: Embracing the Complexity

Proteomes are complex-much more so than genomes or transcriptomes. Thus, simplifying their analysis does not simplify the issue. Proteomes are of proteoforms, not canonical proteins. While having a catalogue of amino acid sequences provides invaluable information, this is the Proteome-lite. To dissect biological mechanisms and identify critical biomarkers/drug targets, we must assess the myriad of proteoforms that arise at any point before, after, and between translation and transcription (e.g., isoforms, splice variants, and post-translational modifications [PTM]), as well as newly defined species. There are numerous analytical methods currently used to address proteome depth and here we critically evaluate these in terms of the current 'state-of-the-field'. We thus discuss both pros and cons of available approaches and where improvements or refinements are needed to quantitatively characterize proteomes. To enable a next-generation approach, we suggest that advances lie in transdisciplinarity via integration of current proteomic methods to yield a unified discipline that capitalizes on the strongest qualities of each. Such a necessary (if not revolutionary) shift cannot be accomplished by a continued primary focus on proteo-genomics/-transcriptomics. We must embrace the complexity. Yes, these are the hard questions, and this will not be easy…but where is the fun in easy?

Intact Protein Mass Spectrometry for Therapeutic Protein Quantitation, Pharmacokinetics, and Biotransformation in Preclinical and Clinical Studies: An Industry Perspective

Recent advancements in immunocapture methods and mass spectrometer technology have enabled intact protein mass spectrometry to be applied for the characterization of antibodies and other large biotherapeutics from in-life studies. Protein molecules have not been traditionally studied by intact mass or screened for catabolites in the same manner as small molecules, but the landscape has changed. Researchers have presented methods that can be applied to the drug discovery and development stages, and others are exploring the possibilities of the new approaches. However, a wide variety of options for assay development exists without clear recommendation on best practice, and data processing workflows may have limitations depending on the vendor. In this perspective, we share experiences and recommendations for current and future application of mass spectrometry for biotherapeutic molecule monitoring from preclinical and clinical studies.

Plant-based vaccines and cancer therapy: Where are we now and where are we going?

Therapeutic vaccines are an effective approach in cancer therapy for treating the disease at later stages. The Food and Drug Administration (FDA) recently approved the first therapeutic cancer vaccine, and further studies are ongoing in clinical trials. These are expected to result in the future development of vaccines with relatively improved efficacy. Several vaccination approaches are being studied in pre-clinical and clinical trials, including the generation of anti-cancer vaccines by plant expression systems.This approach has advantages, such as high safety and low costs, especially for the synthesis of recombinant proteins. Nevertheless, the development of anti-cancer vaccines in plants is faced with some technical obstacles.Herein, we summarize some vaccines that have been used in cancer therapy, with an emphasis on plant-based vaccines.

Animal Immunization, in Vitro Display Technologies, and Machine Learning for Antibody Discovery

For years, a discussion has persevered on the benefits and drawbacks of antibody discovery using animal immunization versus in vitro selection from non-animal-derived recombinant repertoires using display technologies. While it has been argued that using recombinant display libraries can reduce animal consumption, we hold that the number of animals used in immunization campaigns is dwarfed by the number sacrificed during preclinical studies. Thus, improving quality control of antibodies before entering in vivo studies will have a larger impact on animal consumption. Both animal immunization and recombinant repertoires present unique advantages for discovering antibodies that are fit for purpose. Furthermore, we anticipate that machine learning will play a significant role within discovery workflows, refining current antibody discovery practices.

Location of OprD porin in Pseudomonas aeruginosa clinical isolates

Multidrug-resistant Pseudomonas aeruginosa is one of the main opportunistic pathogens causing severe infection. One of the mechanisms involved in the resistance to imipenem in clinical isolates is the loss of the OprD porin. Changes like substitutions, deletions, insertions, or mutations in the oprD gene can modify the conformation of OprD porin or inhibit its presence and generate resistance to carbapenems. The aim of this work was to obtain anti-OprD polyclonal antibodies and to determine by both immunofluorescence microscopy (IFI) and Western blot assays, the presence of the OprD porin in resistant-carbapenem P. aeruginosa strains with different changes in the oprD gene. Changes in the gene oprD were identified in clinical isolates of P. aeruginosa. When proteins were translated, several polymorphisms were found; however, these did not affect the presence of OprD porin (PCM25, PCM36, and PCM78). Also it was detected an insertion sequence ISPa1328 (PCM52) and a premature stop codon (PCM91), which inhibited the presence of the OprD porin. This study shows how changes in the oprD gene of P. aeruginosa clinical isolates affect the presence of the OprD porin detected by Western blot and indirect immunofluorescence assays using specific polyclonal anti-OprD antibodies generated in this work.

Recent advances in dual recognition based surface enhanced Raman scattering for pathogenic bacteria detection: A review

Rapid and reliable detection of pathogenic bacteria at the early stage represents a highly topical research area for food safety and public health. Although culture based method is the gold standard method for bacteria detection, recent techniques have promoted the development of alternative methods, such as surface enhanced Raman scattering (SERS). SERS provides additional advantages of high speed, simultaneous detection and characterization, multiplex analysis, and comparatively low cost. However, conventional SERS methods for bacteria detection are facing limitations of low sensitivity, susceptible to matrix interference, and poor accuracy. In recent years, specific detection of pathogenic bacteria with dual recognition based SERS methods has attracted increasing attentions. These methods include two steps recognition of target bacteria, and integrate the functions of target separation and detection. Considering their merits of excellent specificity, ultrahigh sensitivity, multiplex detection capability, and potential for on-site applications, these methods are promising alternatives for rapid and reliable detection of pathogenic bacteria. Herein, this review aims to summarize the recent advances in dual recognition based SERS methods for specific detection of pathogenic bacteria. Their advantages and limitations are discussed, and further perspectives are tentatively given. This review provides new insights into the application of SERS as a reliable tool for pathogenic bacteria detection.

Design and Fabrication of Silicon Nanowire-Based Biosensors with Integration of Critical Factors: Toward Ultrasensitive Specific Detection of Biomolecules

As critical factors affecting the sensing performance of silicon nanowire (SiNW) biosensors, the structure, functional interface, and detection target were analyzed and designed to improve sensing performance. For an improved understanding of the dependence of sensor structure on sensitivity, a simple theoretical analysis was proposed to predict the sensitivity of biosensors with different SiNW types, widths, and doping concentrations. Based on the theoretical analysis, a biosensor integrating optimized critical factors was designed and fabricated. Optimizations focusing on the following aspects are considered: (1) employing n-type SiNW and controlling the impurity doping concentration of SiNW at approximately 2 × 10¹⁶-6 × 10¹⁶ atoms/cm³ to obtain a suitable charge density, (2) minimizing the SiNW width to 16.0 nm to increase the surface area-to-volume ratio, (3) using a native oxide layer on SiNW as a gate insulator to transport the captured charge molecules closer to the SiNW surface, (4) modifying the SiNW surface by 2-aminoethylphosphonic acid coupling to form a high-density self-assembled monolayer for enhancing the stability bound molecules, and (5) functionalizing the SiNW with ovalbumin molecules for specifically capturing the target immunoglobulin G (IgG) molecules. The sensing performance was evaluated by detecting IgG with concentrations ranging from 6 aM to 600 nM and control experiments. The SiNW biosensor revealed ultrahigh sensitivity and specific detection of target IgG with a measured limit of detection of 6 aM. The integration of the critical SiNW biosensor factors provides a significant possibility of a rapid and ultrasensitive diagnosis of diseases at their early stages.

Development and Application of Novel Chemiluminescence Immunoassays for Highly Sensitive Detection of Anisakis simplex Proteins in Thermally Processed Seafood

The third-stage larvae (L3) of Anisakis simplex are the most important source of hidden allergens in seafood products. However, there exist no commercial methods for detecting Anisakis proteins in food. Furthermore, only a few methods have been validated for the detection of A. simplex in thermally processed food. The aims of our study are (i) the development and validation of high-sensitivity chemiluminescent (CL) immunoassays for the detection of A. simplex proteins in processed seafood, (ii) and A. simplex antigen detection in common seafood products from Polish markets. We developed and validated CL sandwich ELISA (S-ELISA) and CL competitive ELISA (C-ELISA) methods for A. simplex proteins detection in food, with respective detection limits of 0.5 and 5 ng/mL. The usefulness of the assays for detecting A. simplex proteins in highly processed food was evaluated by examination of autoclaved canned fish spiked with A. simplex larvae (1–8 larvae/200 g). Commercial real-time PCR was unable to detect A. simplex in autoclaved samples at all levels of enrichment with Anisakis larvae. CL-S-ELISA was used to test various types of seafood products from Polish markets. Among all tested products (n = 259), 28% were positive. A. simplex antigens were found mostly (n = 39) in smoked fish products: mackerel, herring, cod, and hake. Other positive samples were found in marinated herrings, canned cod livers, canned mackerels, and surimi sticks. In tuna, Atlantic argentine, anchovy, sardine, sprat, and squid products, A. simplex antigens were not detected. This study provides novel effective tools for the detection of A. simplex proteins in processed food and highlights the potential allergic hazards for Anisakis-sensitized Polish consumers of seafood.