CoV2 Paired Antibody
Description
Definition and Mechanism of CoV2 Paired Antibodies
CoV2 paired antibodies are engineered or naturally isolated mAb pairs that bind to non-overlapping regions of SARS-CoV-2 proteins, such as the spike (S) or nucleocapsid (N). These pairs function synergistically to:
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Improve antigen detection in diagnostic assays by increasing sensitivity and reducing cross-reactivity with related coronaviruses (e.g., SARS-CoV-1) .
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Enhance viral neutralization by blocking multiple entry mechanisms or stabilizing antibody-antigen interactions .
Key Mechanistic Insights:
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Epitope Diversity: Pairs like mAbs 46/349 (anti-S1) and 192/267 (anti-N) bind distinct linear epitopes, preventing steric hindrance and enabling simultaneous detection .
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Structural Stabilization: Heavy-light chain pairing (e.g., public clonotypes targeting the receptor-binding domain (RBD)) improves binding affinity by up to 0.234–0.451 nM .
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Cross-Reactivity Control: Some pairs (e.g., mAbs 124/349) cross-react with SARS-CoV-1, while others (e.g., mAb 46-based pairs) remain SARS-CoV-2-specific due to epitope variations .
Antibody Pair Selection
AI-Driven Design
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PALM-H3 Model: Generated CDRH3 sequences targeting SARS-CoV-2 variants (e.g., XBB) with binding affinities comparable to natural antibodies .
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A2binder Algorithm: Predicted epitope-antibody interactions with 89% accuracy, enabling rapid identification of high-affinity pairs .
Performance in Lateral Flow Assays
| Target Protein | mAb Pair | Cross-Reactivity | Sensitivity vs. RT-PCR Ct <25 | Source |
|---|---|---|---|---|
| SARS-CoV-2 N | 192 + 267 | SARS-CoV-1 N | 98% | |
| SARS-CoV-2 S1 | 46 + 349 | None | 95% |
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Clinical Validation: Nasal swab testing showed inverse correlation between pixel intensity (normalized grey scale <140) and Ct values (R² = 0.82) .
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Storage Stability: Antibody pairs retained functionality in hemaPEN® microsampling devices for 35 weeks at room temperature .
Bispecific Antibodies
Stanford-developed CoV2-biRN bispecific antibodies combine:
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NTD-binding mAb: Targets a conserved, low-mutation region (Spike N-terminal domain).
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RBD-binding mAb: Blocks ACE2 interaction (IC₅₀ = 0.038 µg/mL for pseudovirus) .
Key Outcomes:
Cross-Reactive Public Clonotypes
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Group 1/2 mAbs: Target conserved S2 epitopes (e.g., K814, Y917) with 100% cross-reactivity against SARS-CoV-1 .
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Group 3 mAbs: RBD-specific pairs (e.g., 11-2G/18-4A) achieved IC₅₀ = 0.195 µg/mL against authentic virus .
Challenges and Future Directions
Product Specs
The SARS Coronavirus, an enveloped virus, possesses three key outer structural proteins: membrane (M), envelope (E), and spike (S) proteins. The spike (S) glycoprotein plays a crucial role in virus infection by interacting with a cellular receptor to facilitate membrane fusion, enabling the virus to enter susceptible target cells. Due to its involvement in the viral entry process, the S-protein is a primary target for neutralizing antibodies. Studies have confirmed that SARS is caused by a human coronavirus, a major contributor to upper respiratory tract illnesses like the common cold. These coronaviruses, classified as positive-stranded RNA viruses, possess the largest known viral RNA genomes (27-31 kb). The infection process begins with the binding of the viral spike protein, a 139-kDa protein, to specific receptors on host cells. Being the main surface antigen of the coronavirus, the spike protein is critical for this interaction. Notably, a 46 kDa nucleocapsid protein is prominently observed in culture supernatants infected with the SARS virus, suggesting its potential as a significant immunogen for early diagnostic applications.
This product consists of a pair of SARS CoV2 antibodies: a coating antibody (C865) and a conjugating antibody (C866), both targeting the CoV2 nucleoprotein. Designed specifically for the development of CoV2 antigen rapid tests, these antibodies facilitate the detection of CoV-2 nucleoprotein. Notably, they exhibit high specificity and do not cross-react with CoV nucleoproteins from 229E, HKU1, NL63, or OC43. CoV2 antigen rapid tests prepared using this antibody pair demonstrate a detection sensitivity of 5ng/ml for recombinant SARS-CoV2 nucleoprotein.
It is important to note that when ordering a specific quantity, for instance, 100µg of antibody, the shipment will contain 50µg of each antibody, totaling 100µg.
Greater than 90%.
The product is provided as two vials containing sterile filtered, clear, and colorless solutions.
The antibodies are formulated in phosphate-buffered saline (PBS) at a pH of 7.4.
While the SARS CoV2 antibodies, both coating and conjugating, remain stable at 4°C for up to one week, storage at or below -18°C is recommended. For long-term storage, adding a carrier protein such as 0.1% HSA or BSA is advisable. To maintain optimal antibody performance, avoid repeated freeze-thaw cycles.
These antibodies are specifically developed and validated for use in lateral flow rapid test applications.
Purified monoclonal IgG by protein A chromatography.
Mouse antibody Monoclonal.
Q&A
What are the primary target proteins for SARS-CoV-2 antibody detection in paired studies?
SARS-CoV-2 antibody research primarily focuses on the receptor-binding domain (RBD) and S1 subunit of the spike protein, as well as the nucleocapsid (N) protein. These targets differ in their utility for various research applications:
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Spike protein components: RBD and S1 antibodies correlate better with neutralizing activity and potential protection
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Nucleocapsid protein: N-specific antibodies typically show greater sensitivity for detecting prior infection
Research demonstrates that monoclonal antibody pairs targeting the N protein achieve lower limits of detection (0.76–6.95 ng/ml) compared to S1-targeting pairs (4.89–9.06 ng/ml), making N-directed antibodies potentially more sensitive for diagnostic applications .
How do antibody responses to different SARS-CoV-2 proteins evolve over time in paired sera?
Longitudinal studies using paired samples reveal distinct evolution patterns for different antibody isotypes and antigen targets:
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Anti-RBD IgM shows the greatest decrease (53%) between 1.3 and 6.2 months post-infection
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Anti-RBD IgG decreases by approximately 32% during the same period
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Anti-RBD IgA shows the smallest decrease (15%)
Importantly, the magnitude of decrease is inversely proportional to initial antibody levels, with individuals having higher initial levels showing greater relative changes . Researchers should consider these differential decay rates when designing longitudinal studies or interpreting serological data from different timepoints.
What methodological approaches are recommended for paired antibody sample collection?
Recent research validates several approaches for paired antibody sample collection:
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Traditional venipuncture: The gold standard for serum antibody analysis
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Dried blood spot (DBS) microsampling: The hemaPEN® device shows high correlation with venipuncture samples (r = 0.9472, p < 0.0001 for RBD-specific IgG; r = 0.6892, p < 0.0001 for S1-specific IgG)
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Paired fingerprick sampling: Particularly valuable for pediatric studies and remote settings
For longitudinal studies, the stability of antibodies in different storage conditions is essential. Research demonstrates that S1-specific IgG levels remain stable in hemaPEN DBS samples stored at room temperature for up to 35 weeks, offering practical advantages for field research .
How can researchers develop and select optimal monoclonal antibody pairs for SARS-CoV-2 antigen detection?
Developing effective monoclonal antibody pairs requires systematic immunization, screening, and validation approaches:
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Immunization protocol: Immunize BALB/c mice with purified SARS-CoV-2 S1 and N proteins expressed in eukaryotic cells to ensure proper protein folding and post-translational modifications
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Hybridoma generation: From seroconverted animals with high antibody titers, generate hybridomas through cell fusion
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Cross-reactivity screening: Test candidates against related coronaviruses (MERS, NL63, 229E, HKU1, and OC43) to ensure specificity
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Pairwise evaluation: Test purified mAbs in complementary combinations to identify pairs with optimal binding characteristics
Selection criteria should include:
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Low limits of detection (ideally <1 ng/ml for N protein targets)
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High specificity (minimal binding to other coronaviruses)
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Binding to conserved epitopes that remain consistent across variants
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Spatial compatibility of paired antibodies (non-competing epitopes)
What factors influence the sensitivity and specificity of paired antibody diagnostic approaches?
Several critical factors determine the performance of paired antibody diagnostics:
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Target protein selection: N protein-directed tests generally achieve lower detection limits than S1-directed tests
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Viral load correlation: Test sensitivity correlates with sample Ct values; tests typically detect samples with Ct values below 31.2, corresponding to the acute infectious phase
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Epitope conservation: Antibodies targeting conserved regions remain effective against emerging variants
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Spatial arrangement: Optimal antibody pairs bind to distinct, non-competing epitopes
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Sample processing: Standardized protocols for sample collection, storage, and processing are essential
For example, a rapid antigen test composed of mAbs 1 and 453 targeting the N protein demonstrated 84.6% sensitivity (11/13) and 100% specificity (10/10) in clinical evaluation .
How can researchers map and characterize antibody binding to SARS-CoV-2 spike protein?
Advanced characterization of antibody binding involves multiple complementary approaches:
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Competition-based mapping: Identify antibodies that compete for binding, suggesting overlapping epitopes
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Community classification: Group antibodies into "communities" based on competition patterns
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Electron microscopy: Determine the precise binding "footprint" of each antibody community on the spike protein surface
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Neutralization correlation: Assess how binding to specific epitopes correlates with neutralizing activity
The Coronavirus Immunotherapeutic Consortium (CoVIC) has mapped 370 antibodies against the spike protein, categorizing them into seven distinct "communities" based on binding patterns. This mapping helps predict how mutations might affect antibody binding and informs the design of complementary antibody pairs that target non-overlapping epitopes .
How should researchers interpret paired antibody test results in relation to SARS-CoV-2 immunity?
Interpretation of paired antibody results requires careful consideration of multiple factors:
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Temporal dynamics: Antibody levels typically increase within the first week of hospital admission, even in PCR-negative patients with clinical COVID-19
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Isotype patterns: Different isotypes (IgG, IgM, IgA) follow distinct kinetics, with IgG to S-protein showing strong correlation (rs = 0.75) with RBD antibody levels
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Disease severity correlation: More pronounced decreases in IgA levels occur in severe COVID-19 patients compared to moderate cases
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Protection indicators: While antibody presence correlates with protection, other factors including T-cell immunity play important roles
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Reinfection risk: Individuals with positive antibody tests show declining risk of subsequent positive PCR tests beyond 30 days, suggesting protective immunity
Researchers should note that vaccination is recommended regardless of antibody status due to the standardized immune response it provides .
How do paired antibody responses differ between patient populations?
Studies comparing paired samples reveal important differences in antibody responses:
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Age-related differences: Both adult and pediatric populations show similar correlations between serum and DBS antibody measurements, but absolute levels may differ
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Disease severity impact: Individuals with persistent post-acute symptoms show significantly higher levels of anti-RBD IgG and anti-N total antibody at both early and late timepoints
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PCR status correlation: Antibody conversion can confirm SARS-CoV-2 infection in PCR-negative patients with clinical symptoms
For comprehensive population studies, researchers should consider both demographic factors and clinical characteristics when analyzing paired antibody responses.
What approaches exist for studying paired antibody responses to SARS-CoV-2 variants?
As variants of concern (VOCs) continue to emerge, researchers need robust approaches to assess cross-reactivity:
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Rationally designed antibody pairs: Select antibodies targeting conserved epitopes that maintain binding across variants
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Comparative binding assays: Test antibody pairs against recombinant proteins from multiple variants
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Neutralization comparisons: Assess functional neutralization against pseudotyped or live virus representing different variants
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Epitope mapping: Characterize how specific mutations affect antibody binding sites
Research has identified antibody pairs like 6H7–6G3 that effectively bind to multiple SARS-CoV-2 variants and even cross-react with SARS-CoV, making them promising candidates for broad-spectrum diagnostic applications .
What standardization approaches are recommended for paired antibody studies?
To ensure reproducibility and comparability across studies, researchers should implement these standardization practices:
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Reference materials: Use international standards for antibody quantification
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Consistent timing: Standardize sampling timepoints (e.g., days from symptom onset or PCR positivity)
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Uniform reporting: Report antibody levels in binding antibody units (BAU) rather than arbitrary units
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Method validation: Validate assay performance using well-characterized reference panels
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Cross-platform calibration: Include calibration controls when comparing results across different platforms or laboratories
Standardized approaches allow for meaningful data integration across studies and facilitate meta-analyses of antibody responses.
How can researchers optimize paired antibody assays for detecting SARS-CoV-2 in complex samples?
Optimization strategies for complex biological samples include:
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Sample preparation protocols: Standardize extraction methods for different sample types
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Buffer optimization: Adjust buffer compositions to minimize non-specific binding
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Signal amplification: Implement enzymatic or nanoparticle-based signal enhancement
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Multiplexing: Develop assays that simultaneously detect multiple antibody isotypes and/or antigens
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Validation with clinical specimens: Test performance using contrived samples that mimic clinical specimens
Laboratory testing shows that gold nanoparticle-based rapid tests can achieve detection limits in the nanogram/milliliter range when optimized properly .
What are the most promising future directions for SARS-CoV-2 paired antibody research?
Several emerging areas show particular promise:
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Long-term immunity tracking: Extended longitudinal studies to assess antibody persistence and memory B cell evolution beyond 6 months
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Mucosal immunity assessment: Development of paired sampling approaches for mucosal antibodies (particularly IgA)
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Artificial intelligence integration: Machine learning algorithms to predict antibody function from binding characteristics
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Integrated B and T cell immunity: Combined approaches to assess both humoral and cellular immune responses
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Next-generation diagnostics: Ultrasensitive detection platforms leveraging optimized antibody pairs
The evolution of memory B cell responses to SARS-CoV-2 continues beyond 6 months post-infection in a manner consistent with antigen persistence, suggesting ongoing germinal center activity . This observation opens new research questions about long-term immunity dynamics.
Product Science Overview
The COVID-19 pandemic, caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has led to a global health crisis. The development of effective therapeutics and vaccines has been a priority. Among the various strategies, monoclonal antibodies (mAbs) have shown promise in neutralizing the virus and preventing infection. Mouse anti-SARS-CoV-2 paired antibodies are a significant area of research in this context.
Mouse anti-SARS-CoV-2 antibodies are typically generated by immunizing mice with SARS-CoV-2 antigens, such as the spike protein or its receptor-binding domain (RBD). The immune response in mice leads to the production of antibodies that can specifically bind to these antigens. Hybridoma technology is often used to produce monoclonal antibodies from the immunized mice. This involves fusing antibody-producing B cells from the mice with myeloma cells to create hybrid cells that can be cultured to produce large quantities of the desired antibodies .
The generated antibodies are then characterized for their binding affinity, specificity, and neutralizing capability. One study described the generation of a panel of murine mAbs directed against the RBD of SARS-CoV-2. Among these, one antibody, 2B04, demonstrated remarkable potency in neutralizing the virus in vitro with a half-maximal inhibitory concentration (IC50) of less than 2 ng/ml . In a murine model of SARS-CoV-2 infection, 2B04 protected the challenged animals from weight loss, reduced lung viral load, and blocked systemic dissemination .
Mouse anti-SARS-CoV-2 paired antibodies are valuable tools in both research and therapeutic applications. In research, they are used to study the virus’s mechanisms of infection and to develop diagnostic assays. In therapeutics, these antibodies can be used as a form of passive immunization to provide immediate protection against the virus. They are also being explored as potential treatments for COVID-19, either alone or in combination with other antiviral agents .
While mouse anti-SARS-CoV-2 antibodies have shown promise, there are challenges associated with their use. One major challenge is the potential for immunogenicity when used in humans, as mouse antibodies can be recognized as foreign by the human immune system. To address this, humanization techniques are employed to modify the mouse antibodies to be more similar to human antibodies. Additionally, ongoing research is focused on improving the efficacy and stability of these antibodies to enhance their therapeutic potential .
In conclusion, mouse anti-SARS-CoV-2 paired antibodies represent a crucial area of research in the fight against COVID-19. Their ability to neutralize the virus and provide protection in animal models highlights their potential as both research tools and therapeutic agents. Continued advancements in this field will be essential for developing effective interventions against SARS-CoV-2 and future emerging pathogens.
