A Highly Sensitive and Group-Specific Enzyme-Linked Immunosorbent Assay (ELISA) for the Detection of AFB1 in Agriculture and Aquiculture Products.

Aflatoxins (AFs) including AFB1, AFB2, AFG1 and AFG2 are widely found in agriculture products, and AFB1 is considered one of the most toxic and harmful mycotoxins. Herein, a highly sensitive (at the pg mL-1 level) and group-specific enzyme-linked immunosorbent assay (ELISA) for the detection of AFB1 in agricultural and aquiculture products was developed. The AFB1 derivative containing a carboxylic group was synthesized and covalently linked to bovine serum albumin (BSA). The AFB1-BSA conjugate was used as an immunogen to immunize mice. A high-quality monoclonal antibody (mAb) against AFB1 was produced by hybridoma technology, and the mAb-based ELISA for AFB1 was established. IC50 and limit of detection (LOD) of the ELISA for AFB1 were 90 pg mL-1 and 18 pg mL-1, respectively. The cross-reactivities (CRs) of the assay with AFB2, AFG1, and AFG2 were 23.6%, 42.5%, and 1.9%, respectively, revealing some degree of group specificity. Corn flour, wheat flour, and crab roe samples spiked with different contents of AFB1 were subjected to ELISA procedures. The recoveries and relative standard deviation (RSD) of the ELISA for AFB1 in spiked samples were 78.3-116.6% and 1.49-13.21% (n = 3), respectively. Wheat flour samples spiked with the mixed AF (AFB1, AFB2, AFG1, AFG2) standard solution were measured by ELISA and LC-MS/MS simultaneously. It was demonstrated that the proposed ELISA can be used as a screening method for evaluation of AFs (AFB1, AFB2, AFG1, AFG2) in wheat flour samples.

Potent broadly neutralizing antibody VIR-3434 controls hepatitis B and D virus infection and reduces HBsAg in humanized mice.

BACKGROUND & AIMS: Chronic hepatitis B is a global public health problem, and coinfection with hepatitis delta virus (HDV) worsens disease outcome. Here, we describe a hepatitis B virus (HBV) surface antigen (HBsAg)-targeting monoclonal antibody (mAb) with the potential to treat chronic hepatitis B and chronic hepatitis D. METHODS: HBsAg-specific mAbs were isolated from memory B cells of HBV vaccinated individuals. In vitro neutralization was determined against HBV and HDV enveloped with HBsAg representing eight HBV genotypes. Human liver-chimeric mice were treated twice weekly with a candidate mAb starting 3 weeks post HBV inoculation (spreading phase) or during stable HBV or HBV/HDV coinfection (chronic phase). RESULTS: From a panel of human anti-HBs mAbs, VIR-3434 was selected and engineered for pre-clinical development. VIR-3434 targets a conserved, conformational epitope within the antigenic loop of HBsAg and neutralized HBV and HDV infection with higher potency than hepatitis B immunoglobulins in vitro. Neutralization was pan-genotypic against strains representative of HBV genotypes A-H. In the spreading phase of HBV infection in human liver-chimeric mice, a parental mAb of VIR-3434 (HBC34) prevented HBV dissemination and the increase in intrahepatic HBV RNA and covalently closed circular DNA. In the chronic phase of HBV infection or co-infection with HDV, HBC34 treatment decreased circulating HBsAg by >1 log and HDV RNA by >2 logs. CONCLUSIONS: The potently neutralizing anti-HBs mAb VIR-3434 reduces circulating HBsAg and HBV/HDV viremia in human liver-chimeric mice. VIR-3434 is currently in clinical development for treatment of patients with chronic hepatitis B or D. IMPACT AND IMPLICATIONS: Chronic infection with hepatitis B virus and co-infection with hepatitis D virus place approximately 290 million individuals worldwide at risk of severe liver disease and cancer. Available treatments result in low rates of functional cure or require lifelong therapy that does not eliminate the risk of liver disease. We isolated and characterized a potent human antibody that neutralizes hepatitis B and D viruses and reduces infection in a mouse model. This antibody could provide a new treatment for patients with chronic hepatitis B and D.

A novel plant-made monoclonal antibody enhances the synergetic potency of an antibody cocktail against the SARS-CoV-2 Omicron variant.

This study describes a novel, neutralizing monoclonal antibody (mAb), 11D7, discovered by mouse immunization and hybridoma generation, against the parental Wuhan-Hu-1 RBD of SARS-CoV-2. We further developed this mAb into a chimeric human IgG and recombinantly expressed it in plants to produce a mAb with human-like, highly homogenous N-linked glycans that has potential to impart greater potency and safety as a therapeutic. The epitope of 11D7 was mapped by competitive binding with well-characterized mAbs, suggesting that it is a Class 4 RBD-binding mAb that binds to the RBD outside the ACE2 binding site. Of note, 11D7 maintains recognition against the B.1.1.529 (Omicron) RBD, as well neutralizing activity. We also provide evidence that this novel mAb may be useful in providing additional synergy to established antibody cocktails, such as Evusheld™ containing the antibodies tixagevimab and cilgavimab, against the Omicron variant. Taken together, 11D7 is a unique mAb that neutralizes SARS-CoV-2 through a mechanism that is not typical among developed therapeutic mAbs and by being produced in ΔXFT Nicotiana benthamiana plants, highlights the potential of plants to be an economic and safety-friendly alternative platform for generating mAbs to address the evolving SARS-CoV-2 crisis.

Obtaining acidic and basic charge variants using a twin-column continuous chromatography system.

For recombinantly produced monoclonal antibody (mAb), charge variants including acidic and basic species are common heterogeneities. For characterization purpose, sufficient amount of acidic and basic species with high purity is needed. In this work, we developed an approach that allows for continuous separating and collecting of acidic and basic charge variants. First, with batch-mode cation exchange (CEX) chromatography, the load density and linear salt gradient elution conditions under which good separation of both charge variants can be achieved were determined. Next, a stepwise elution protocol was developed based on the linear gradient elution. Finally, acidic and basic charge variants were persistently produced under stepwise elution using a customized twin-column continuous chromatography system. This approach allows acidic and basic charge variants with high purity (i.e., >90%) to be efficiently generated in sufficient amount, which greatly facilitates the necessary characterization of these mAb variants.

LC-MS Approach to Decipher a Light Chain Chromatographic Peak Splitting of a Monoclonal Antibody.

PURPOSE: Monoclonal antibodies (mAbs), like other protein therapeutics, are prone to various forms of degradation, some of which are difficult to distinguish from the native form yet may alter potency. A generalizable LC-MS approach was developed to enable quantitative analysis of isoAsp. In-depth understanding of product quality attributes (PQAs) enables optimization of the manufacturing process, better formulation selection, and decreases risk associated with product handling in the clinic or during shipment. METHODS: Reversed-phase chromatographic peak splitting was observed when a mAb was exposed to elevated temperatures. Multiple LC-MS based methods were applied to identify the reason for peak splitting. The approach involved the use of complementary HPLC columns, multiple enzymatic digestions and different MS/MS ion dissociation methods. In addition, mAb potency was measured by enzyme-linked immunosorbent assay (ELISA). RESULTS: The split peaks had identical masses, and the root cause of the peak splitting was identified as isomerization of an aspartic acid located in the complementarity-determining region (CDR) of the light chain. And the early eluting and late eluting peaks were collected and performed enzymatic digestion to confirm the isoAsp enrichment in the early eluting peak. In addition, decreased potency was observed in the same heat-stressed sample, and the increased isoAsp levels in the CDR correlate well with a decrease of potency. CONCLUSION: Liquid chromatography-mass spectrometry (LC-MS) has been utilized extensively to assess PQAs of biological therapeutics. In this study, a generalizable LC-MS-based approach was developed to enable identification and quantitation of the isoAsp-containing peptides.

WAVE-based intensified perfusion cell culture for fast process development.

OBJECTIVE: This study was to evaluate the feasibility of using a rocking type bioreactor system, specifically the WAVE 25, in an intensified perfusion culture (IPC) mode for monoclonal antibody (mAb) production in Chinese hamster ovary (CHO) cell line. METHODS: A disposable perfusion bag with floating membrane was used in the IPC process. An automated filter switching system was employed to continuously clarify the harvested post-membrane culture fluid. The overall cell culture performance, product titer, and quality were compared to those of a typical IPC conducted in a bench-top glass bioreactor. RESULTS: The results showed that the overall trends of cell culture performance, product titer (accumulated harvest volumetric titer) were similar to those of the typical IPC conducted in the glass bioreactor, while the purity related quality were slightly better than the typical run. Furthermore, with the automated filter switching system, the harvested post-membrane culture fluid could be continuously clarified, making it suitable for downstream continuous chromatography. CONCLUSION: The study demonstrated the feasibility of using the WAVE-based rocking type bioreactor in the N stage IPC process, which increases the flexibility in adopting IPC process. The results suggest that the rocking type bioreactor system could be a viable alternative to traditional stirred tank bioreactors for perfusion culture in the biopharmaceutical industry.

Treatment of Alzheimer's Disease: Beyond Symptomatic Therapies.

In an ever-increasing aged world, Alzheimer's disease (AD) represents the first cause of dementia and one of the first chronic diseases in elderly people. With 55 million people affected, the WHO considers AD to be a disease with public priority. Unfortunately, there are no final cures for this pathology. Treatment strategies are aimed to mitigate symptoms, i.e., acetylcholinesterase inhibitors (AChEI) and the N-Methyl-D-aspartate (NMDA) antagonist Memantine. At present, the best approaches for managing the disease seem to combine pharmacological and non-pharmacological therapies to stimulate cognitive reserve. Over the last twenty years, a number of drugs have been discovered acting on the well-established biological hallmarks of AD, deposition of ß-amyloid aggregates and accumulation of hyperphosphorylated tau protein in cells. Although previous efforts disappointed expectations, a new era in treating AD has been working its way recently. The Food and Drug Administration (FDA) gave conditional approval of the first disease-modifying therapy (DMT) for the treatment of AD, aducanumab, a monoclonal antibody (mAb) designed against Aß plaques and oligomers in 2021, and in January 2023, the FDA granted accelerated approval for a second monoclonal antibody, Lecanemab. This review describes ongoing clinical trials with DMTs and non-pharmacological therapies. We will also present a future scenario based on new biomarkers that can detect AD in preclinical or prodromal stages, identify people at risk of developing AD, and allow an early and curative treatment.

An Extremely Highly Sensitive ELISA in pg mL-1 Level Based on a Newly Produced Monoclonal Antibody for the Detection of Ochratoxin A in Food Samples.

In this study, an extremely highly sensitive enzyme-linked immunosorbent assay (ELISA) based on a newly produced monoclonal antibody (mAb) for the detection of ochratoxin A (OTA) in food samples was developed. OTA-Bovine serum albumin (BSA) conjugate was prepared and used as the immunogen for the production of the mAb. Among four hybridoma clones (8B10, 5C2, 9B7, and 5E11), the antibody from 8B10 displayed the highest affinity recognition for OTA. Based on the mAb (8B10), the IC50 and LOD of the ELISA for OTA were 34.8 pg mL-1 and 1.5 pg mL-1, respectively, which was 1.53~147 times lower than those in published ELISAs, indicating the ultra-sensitivity of our assay. There was no cross-reactivity of the mAb with the other four mycotoxins (AFB1, ZEN, DON, and T-2). Due to the high similarity in molecular structures among OTA, ochratoxin B (OTB), and ochratoxin C (OTC), the CR values of the mAb with OTB and OTC were 96.67% and 22.02%, respectively. Taking this advantage, the ELISA may be able to evaluate total ochratoxin levels in food samples. The recoveries of the ELISA for OTA in spiked samples (corn, wheat, and feed) were 96.5-110.8%, 89.5-94.4%, and 91.8-113.3%; and the RSDs were 5.2-13.6%, 8.2-13.0%, and 7.7-13.7% (n = 3), respectively. The spiked food samples (corn) were measured by ELISA and HPLC-FLD simultaneously. A good correlation between ELISA (x) and HPLC-FLD (y) with the linear regression equation of y = 0.918x - 0.034 (R2 = 0.985, n = 5) was obtained. These results demonstrated that the newly produced mAb-based ELISA was a feasible and ultra-sensitive analytical method for the detection of OTA in food samples.

ImmunoPET of trophoblast cell-surface antigen 2 (Trop-2) expression in pancreatic cancer.

PURPOSE: Without a standard test for pancreatic carcinomas, this highly lethal disease is normally diagnosed at its advanced stage, leading to a low survival rate of patients. Trophoblast cell-surface antigen 2 (Trop-2), a transmembrane glycoprotein, is associated with cell proliferation and highly expressed in most of solid epithelial tumors, including pancreatic cancer. A non-invasive method of imaging Trop-2 would greatly benefit clinical diagnosis and monitoring of pancreatic cancer. In the current study, 89Zr-labeled anti-Trop-2 antibody (AF650) was recruited for the systemic evaluation of Trop-2 as an immunoPET target for pancreatic cancer imaging. METHODS: AF650 was conjugated with desferrioxamine (DFO) and then radiolabeled with 89Zr. Trop-2 expression levels were determined in three pancreatic cancer cell lines (BxPC-3, MIA PaCa-2, and AsPC-1) via western blot, flow cytometry, saturation binding assay, and immunofluorescence staining. The targeting capacity of 89Zr-DFO-AF650 was evaluated in mouse models with subcutaneous xenograft of pancreatic cancers via PET imaging and bio-distribution studies. In addition, a Trop-2-positive orthotopic cancer model was recruited for further validating the targeting specificity of 89Zr-DFO-AF650. RESULTS: BxPC-3 cells expressed high levels of Trop-2, while AsPC-1 and MIA PaCa-2 cells expressed low levels of Trop-2. Additionally, 89Zr-DFO-AF650 exhibited high specificity to Trop-2 in BxPC-3 cells (Kd = 22.34 ± 2.509 nM). In subcutaneous xenograft models, about 28.8 ± 7.63%ID/g tracer accumulated in the BxPC-3 tumors at 120 h post injection, which was much higher than those reaching MIA PaCa-2 (6.76 ± 2.08%ID/g) and AsPC-1 (3.51 ± 0.69%ID/g) tumors (n = 4). More importantly, 89Zr-DFO-AF650 could efficiently distinguish primary tumors in the orthotopic BxPC-3 cancer model, showing high correlation between PET imaging and bio-distribution and sensitivity. CONCLUSIONS: 89Zr-DFO-AF650 can be effectively used to detect pancreatic cancer via Trop-2-mediated immunoPET in vivo, clearly revealing the great potential of Trop-2-based non-invasive imaging in pancreatic cancer detection and treatment monitoring.

Differential Surface Adsorption Phenomena for Conventional and Novel Surfactants Correlates with Changes in Interfacial mAb Stabilization.

Protein adsorption on surfaces can result in loss of drug product stability and efficacy during the production, storage, and administration of protein-based therapeutics. Surface-active agents (excipients) are typically added in protein formulations to prevent undesired interactions of proteins on surfaces and protein particle formation/aggregation in solution. The objective of this work is to understand the molecular-level competitive adsorption mechanism between the monoclonal antibody (mAb) and a commercially used excipient, polysorbate 80 (PS80), and a novel excipient, N-myristoyl phenylalanine-N-polyetheramine diamide (FM1000). The relative rate of adsorption of PS80 and FM1000 was studied by pendant bubble tensiometry. We find that FM1000 saturates the interface faster than PS80. Additionally, the surface-adsorbed amounts from X-ray reflectivity (XRR) measurements show that FM1000 blocks a larger percentage of interfacial area than PS80, indicating that a lower bulk FM1000 surface concentration is sufficient to prevent protein adsorption onto the air/water interface. XRR models reveal that with an increase in mAb concentration (0.5-2.5 mg/mL: IV based formulations), an increased amount of PS80 concentration (below critical micelle concentration, CMC) is required, whereas a fixed value of FM1000 concentration (above its relatively lower CMC) is sufficient to inhibit mAb adsorption, preventing mAb from co-existing with surfactants on the surface layer. With this observation, we show that the CMC of the surfactant is not the critical factor to indicate its ability to inhibit protein adsorption, especially for chemically different surfactants, PS80 and FM1000. Additionally, interface-induced aggregation studies indicate that at minimum surfactant concentration levels in protein formulations, fewer protein particles form in the presence of FM1000. Our results provide a mechanistic link between the adsorption of mAbs at the air/water interface and the aggregation induced by agitation in the presence of surfactants.

Identification and analysis of B cell epitopes of hemagglutinin of H1N1 influenza virus.

The frequent variation of influenza virus hemagglutinin (HA) antigen is the main cause of influenza pandemic. Therefore, the study of B cell epitopes of HA is of great significance in the prevention and control of influenza virus. In this study, the split vaccine of 2009 H1N1 influenza virus was used as immunogen, and the monoclonal antibodies (mAbs) were prepared by conventional hybridoma fusion and screening techniques. The characteristics of mAbs were identified by ELISA method, Western-blot test and hemagglutination inhibition test (HI). Using the obtained mAbs as a tool, the B cell epitopes of HA were predicted by ELISA blocking test, sandwich ELISA method and computer simulation method. Finally, four mAbs against HA antigen of H1N1 influenza virus were obtained. The results of ELISA and computer prediction showed that there were at least two types of epitopes on HA of influenza virus. The results of this study complemented the existing methods for predicting HA epitopes, and also provided a new method for predicting other pathogenic microorganisms.

Two major mechanisms contributing to copurification of CHO host cell proteins and strategies to minimize their negative impact.

For CHO expressed monoclonal antibodies (mAbs), host cell proteins (HCPs) represent a major class of process-related impurities and their removal is a key focus of downstream process development. HCPs are highly heterogeneous in nature, differing in molecular weight, isoelectric point and hydrophobicity, and some of them can be difficult to remove. Although Protein A affinity chromatography alone can typically remove more than 90% of HCPs in the clarified culture harvest, in many cases reducing HCPs in the final drug product to an acceptable level (e.g., <100 ppm) can still be a challenging task. The relative difficulty of HCP clearance is case dependent and in certain cases a small population of HCPs can persist throughout the downstream process. This article reviews the two major mechanisms that contribute to copurification of CHO HCPs, namely leaching from chromatin heteroaggregates and nonspecific HCP-mAb association. In addition, strategies that can minimize the impact of these two factors are briefly discussed.

Viral removal by column chromatography in downstream processing of monoclonal antibodies.

For monoclonal antibodies (mAbs) produced in mammalian cells, viral safety is a critical concern. The downstream process, in addition to removing other impurities, needs to ensure robust clearance (removal or inactivation) of potential endogenous and adventitious viruses. In general, Protein A and polishing chromatography steps all can provide certain level of virus removal. Chromatographic removal combined with virus inactivation and nanofiltration usually provides adequate virus clearance across the overall downstream process. This article reviews the virus clearance capability of commonly used column chromatography, with attention to possible interference of virus-mAb interaction on virus removal. In addition, the potential of using viral surrogate as a safe alternative to live virus for assessing viral clearance is briefly discussed.

Structural variation and spatial polysaccharide profiling of intervessel pit membranes in grapevine.

BACKGROUND AND AIMS: Intervessel pit membranes (PMs) are important cell wall structures in the vessel system that may impact a plant's water transport and its susceptibility to vascular diseases. Functional roles of intervessel PMs largely depend on their structure and polysaccharide composition, which are the targets of this study. METHODS: With grapevine used as a model plant, this study applied an immunogold-scanning electron microscopy technique to simultaneously analyse at high resolution intervessel PM structures and major pectic and hemicellulosic polysaccharides that make up intervessel PMs. KEY RESULTS: Intervessel PMs in functional xylem showed significant structural variation, with about 90 % of them being structurally intact with smooth or relatively smooth surfaces and the remaining 10 % with progressively degraded structures. The results also elucidated details of the removal process of cell wall materials from the intervessel PM surface toward its depth during its natural degradation. Four groups of pectic and hemicellulosic polysaccharides were immunolocalized in intervessel PMs and differed in their spatial distribution and abundance. Weakly methyl-esterified homogalacturonans (WMe-HGs, detected by JIM5) were abundant in the surface layer, heavily methyl-esterified homogalacturonans (HMe-HGs, detected by JIM7) and xylans detected by CCRC-M140 were mostly found in deeper layers, and fucosylated xyloglucans (F-XyGs, detected by CCRC-M1) were more uniformly distributed at different depths of the intervessel PM. CONCLUSIONS: Intervessel PMs displayed diverse structural variations in grapevine. They contained certain major groups of pectic and hemicellulosic polysaccharides with different spatial distributions and abundance. This information is crucial to reveal the polysaccharide profiling of the primary cell wall and to understand the roles of intervessel PMs in the regulation of water transport as well as in a plant's susceptibility to vascular diseases.

Comparison of originator and biosimilar monoclonal antibodies using HRMS, Fc affinity chromatography, and 2D-HPLC.

Due to the complex manufacturing process of therapeutic monoclonal antibodies, it is hardly possible to produce an identical copy of the original product (originator). Consequently, follow-on products (biosimilars) must demonstrate their efficacy being similar to the originator in terms of structure and function. During this process, a variety of analytical methods are required for this purpose. This study focuses on three particularly relevant analytical techniques: high-resolution mass spectrometry, fragment crystallisable (Fc) affinity chromatography, and two-dimensional peptide mapping. Each analytical method proved able to identify specific differences between originator and biosimilar. High-resolution mass spectrometry was used to characterize the glycan pattern. It was shown that a trastuzumab biosimilar did not have the G0:G0F sugar modification identified in the originator. The application of affinity chromatography to rituximab showed that originator and biosimilar interacted differently with the immobilized Fc receptor. Furthermore, 2D-HPLC peptide mapping demonstrated the influence of orthogonality of separation dimensions, leading to differentiation of a rituximab originator and biosimilar.

Evaluation the reactivity of a peptide-based monoclonal antibody derived from OmpA with drug resistant pulsotypes of Acinetobacter baumannii as a potential therapeutic approach.

BACKGROUND: Acinetobacter baumannii is an opportunistic and antibiotic-resistant pathogen that predominantly causes nosocomial infections. There is urgent need for development nonantibiotic-based treatment strategies. We developed a novel monoclonal antibody (mAb) against a peptide of conserved outer membrane protein A (OmpA) and evaluated its reactivity with different pulsotypes of A. baumannii. METHODS: Peptide derived from A. baumannii OmpA was conjugated to keyhole limpet hemocyanin and injected into BALB/c mice. Splenocytes of immunized mice were fused with SP2/0 myeloma cells followed by selection of antibody-producing hybridoma cells. After screening of different hybridoma colonies by ELISA, one monoclone was selected as 3F10-C9 and the antibody was tested for reaction with five different Acinetobacter pulsotypes that were resistant to carbapenem antibiotics. The affinity constant was measured by ELISA. The ELISA, western blotting, indirect immunofluorescence (IFA), and in vitro opsonophagocytosis assays were used to evaluate the reactivity of generated mAb. RESULTS: The anti-OmpA antibody reacted with the immunizing peptide and had a high affinity (1.94 × 10-9 M) for its antigen in the ELISA. Specific binding of mAb to OmpA was confirmed in Western blot. IFA assays revealed that mAb recognized specific OmpA on the pulsotypes. Opsonophagocytosis assays showed that the mAb increased the bactericidal activity of macrophage cells. The antibody function was higher in the presence of serum complement. CONCLUSIONS: The peptide-based mAb demonstrated optimal performance in laboratory experiments which may be appropriate in investigation on OmpA in Acinetobacter pathogenesis and development of passive immunization as a novel therapeutic approach.

Production of single-chain fragment variable (scFv) antibodies specific to plasma membrane epitopes on bull Y-bearing sperm.

Distinguishing between bull Y- and X-bearing sperm populations is advantageous for techniques using sexed bull semen. The aim of this study was to produce a single-chain fragment variable (scFv) antibody against plasma membrane epitopes on bull Y-bearing sperm. Variable heavy (VH)- and variable light (VL)-region genes generated from a hybridoma cell secreting a specific Y-bearing sperm monoclonal antibody (mAb-1F9) were cloned and expressed. The expected sizes of the DNA bands were ∼350 bp for the VH gene and ∼318 bp for the VL gene. The VH and VL genes were generated and used to construct an scFv gene (∼650 bp), which was expressed in E.coli TG1 cells and produced the corresponding soluble scFv antibody. Compared with the parent mAb-1F9, the scFv antibodies presented a high affinity for Y-bearing sperm and low cross-reactivity with X-bearing sperm. An immunofluorescence analysis confirmed that the scFv antibodies and mAb-1F9 recognize epitopes on the Y-bearing sperm surface. The fluorescence signal was strong on the plasma membrane of Y-bearing sperm but very weak for X-bearing sperm. This study aids the application and production of engineered scFv antibodies specific to Y-bearing sperm to distinguish between Y- and X-bearing sperm populations for techniques involving sexed bull semen.

[Development of a monoclonal antibody-based enzyme-linked immunosorbent assay for determination of vomitoxin (DON) in Coicis Semen].

Coicis Semen is a common bulk medicinal material used for both medicine and food, which has the effect of promoting diuresis, draining dampness, invigorating the spleen and checking diarrhea. It is derived from Coix lacryma-jobi var. ma-yuen of the family Poaceae, and is easily contaminated by fungi such as Fusarium graminearum and F. flavum due to climate reasons to produce vomitoxin. The guiding principles for determination of vomitoxin in Chinese medicinal materials in Chinese Pharmacopoeia are mainly HPLC and LC-MS, which have long detection period and are time-consuming and laborious, and thus cannot meet the requirements of on-site quality inspection of drugs. The complete antigen of vomitoxin-protein was obtained by chemical derivatization of vomitoxin. The monoclonal antibody against vomitoxin was prepared by classic monoclonal antibody preparation technology, and enzyme-linked immunosorbent assay(ELISA) method for detection of vomitoxin in Coicis Semen was established through methodological investigation. The IC_(50) based on the ELISA for vomitoxin in Coicis Semen was 3.88 µg·L~(-1), and the average recoveries and the RSD were 77.32%-93.73% and 4.6%-9.7%, respectively. With the established ELISA method, the vomitoxin residue in 14 batches of Coicis Semen samples were determined and validated by LC-MS, and the correlation between the two assays was found to be 0.997 8, indicating that the established ELISA method could be used for quantitative determination of vomitoxin residue in Coicis Semen and could achieve the rapid quantitative determination of the vomitoxin residue.

Altered binding avidities and improved growth inhibitory effects of novel anti-HER3 mAb against human cancers in the presence of HER1-or HER2-targeted drugs.

HER1-and HER2-targeted drugs are effective in cancer therapy, especially against lung, breast and colon malignancies; however, resistance of cancer cells to HER1-and HER2-targeted therapies is becoming a serious problem. The avidity/affinity constant (KA) and growth inhibitory effect of anti-HER3 rat monoclonal antibodies (mAb, Ab1∼Ab6) in the presence of therapeutic mAb or low-molecular-weight inhibitors against HER family proteins were analyzed by flow cytometry-based Scatchard plots (Splot) and cell proliferation assay. The KA of Ab3 and Ab6, but not Ab1 or Ab4, split into dual (high and low) modes of KA, and Ab6 exhibited greater anti-proliferative effects against LS-174T colon cancer cells in the presence of Pertuzumab (anti-HER2 mAb). A high KA by Ab6 and Ab6-mediated increased growth inhibition were observed against NCI-H1838 lung or BT474 breast cancer cells, respectively, in the presence of Panitumumab (anti-HER1 mAb) or Perutuzumab. A high KA by Ab6 and Ab6-mediated increased anti-proliferative effects against NCI-H1838 or BT474 were also respectively observed in the presence of Erlotinib (HER1 inhibitor) or Lapatinib (HER1/HER2 inhibitor). In HER1-knockout (KO) NCI-H1838, the reactivity and KA of Ab4 increased compared with in parent NCI-H1838. In HER1-KO or HER3-KO SW1116 colon cancer cells, dual modes of KA with Pertuzumab were noted, and the combination Ab6 and Pertuzumab promoted growth inhibition of HER1-KO, but not of parent SW1116.

Interlaboratory method validation of capillary electrophoresis sodium dodecyl sulfate (CE-SDS) methodology for analysis of mAbs.

Capillary electrophoresis sodium dodecyl sulfate (CE-SDS) is an analytical method to assess the purity of proteins, commonly applied to monoclonal antibodies (mAbs) in the biopharmaceutical industry. To address the need to standardize the CE-SDS method in the pharmaceutical industry and to enhance the confidence in method transfer between laboratories operating different commercial capillary electrophoresis (CE) instrument platforms, an interlaboratory CE-SDS method validation was organized involving 13 laboratories in 13 companies on four different types of commercial capillary electrophoresis instruments. In the validation, a commercial mAb therapeutic was used as the sample. The validation process followed the analytical guidelines set by the ICH guidelines (International Conference for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use). The method's precision, accuracy, linearity and range, and limit of quantitation (LOQ) were validated in the study. Variations of all the parameters validated in the study passed the pre-set criteria defined at the beginning of the study. The definition was based on previously published works and the intended application purpose of the CE-SDS method for mAbs. The study proved that the CE-SDS method fits its intended application purpose as a size impurity assay and size heterogeneity characterization assay for mAb therapeutic products. This study is the first time a CE-SDS method is validated by multiple laboratories using different commercial CE instrument platforms and on a commercial mAb therapeutic. Its results will enhance the confidence of the biopharmaceutical industry to develop CE-SDS methods and transfer CE-SDS methods between different laboratories.