Recombinant Viral Antigens for Lateral-Flow Assay Development

Sep 04, 2026

Selecting recombinant viral antigens for lateral-flow assay development starts with the test format and intended analyte. In an antigen-detection sandwich assay, recombinant antigen can support antibody-pair screening, calibration and analytical controls. In an antibody-detection or serology assay, the viral antigen may be immobilized at the test line or coupled to a reporter particle to capture sample antibodies. Strain, sequence boundaries, folding, glycosylation, tag and purification can change epitope presentation and conjugation behavior. Match the antigen to the assay architecture, antibody pair, specimen and development stage.

Quick answer: Choose the exact viral target, strain or serotype and construct before ordering. For antibody-detection LFAs, preserve the epitopes recognized by the intended immune response. For antigen-detection development, use recombinant antigen as a characterized screening or control reagent and confirm that selected antibodies also recognize the native antigen in representative specimens. Beta LifeScience offers catalog viral antigens across coronavirus, influenza, dengue, HIV, Zika, Ebola and other infectious-disease targets. When a standard product does not match the assay, Beta LifeScience can review the requested construct, expression system, quantity and QC requirements and confirm the feasible production route in the quotation.

Catalog Viral Antigen Examples for Lateral-Flow Development

These products are individual examples rather than a preconfigured LFA panel. Review the current product page, available sizes and lot documentation before ordering.

Viral antigen	CAT	Format	Potential use	Key purchasing check	Action
SARS-CoV-2 Spike glycoprotein (S), mFc	BLC-01264P	Mammalian-cell-derived protein fragment; C-terminal mouse Fc	Antibody-binding, serology-antigen comparison or capture feasibility	Sequence boundaries, variant, Fc compatibility and native epitope presentation	View SARS-CoV-2 Spike, BLC-01264P
Biotinylated SARS-CoV-2 Spike RBD, Active	BLK-02327P	HEK293; Arg319–Asn532; C-terminal His/Avi tags	Oriented streptavidin capture, antibody screening or binding studies	Biotin accessibility, ACE2-binding evidence and compatibility with the planned particle or membrane	View Biotinylated Spike RBD, BLK-02327P
Influenza B HA1, B/Athens/97/2012	BLIT-0216	HEK293; amino acids 16–357; C-terminal His tag	Antibody-detection feasibility and strain-reactivity studies	Exact strain, HA1 boundaries, folding and cross-reactivity panel	View Influenza B HA1, BLIT-0216
Dengue NS1, serotype 3	BLIT-0699	E. coli; full-length type-3 immunodominant regions; C-terminal 6×His; listed migration 45 kDa	NS1 antibody-pair screening, analytical controls or serotype comparison	Serotype, assembly state, formulation and recognition by the selected antibody pair	View Dengue NS1 ST3, BLIT-0699
Dengue subtype-2 Envelope, 32 kDa	BLIT-0678	E. coli; amino acids 45–297; domains I and II; 6×His fusion	Serology, antibody screening or flavivirus cross-reactivity studies	Fragment boundaries and conserved versus type-specific epitopes	View Dengue Envelope-2, BLIT-0678
HIV-1 p24, 24 kDa	BLIT-0890	E. coli-derived full-length recombinant p24; 24 kDa	p24 antibody-pair screening, analytical controls or serology development	Sequence or clade relevance, aggregation and recognition by the intended antibody pair	View HIV-1 p24, BLIT-0890
Zika NS1, strain MR-766	BLIT-0991	HEK293; C-terminal His tag	NS1 binding, serology or flavivirus cross-reactivity evaluation	Strain, host-derived processing, NS1 format and dengue cross-reactivity controls	View Zika NS1, BLIT-0991

Product titles and public specifications help narrow the shortlist, but the development team should test each antigen in the final conjugation, membrane, buffer and sample-matrix conditions.

Need a strain-specific viral antigen?

Share your target, accession, construct, expression host, tag, quantity and QC requirements. Beta LifeScience can evaluate catalog, semi-custom and full-custom production options.

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Catalog or Custom Viral Antigen Support

A catalog antigen is an efficient starting point when its strain, sequence, host, tag and formulation align with the prototype. It can support antibody-pair ranking, conjugation trials and analytical controls. For a different construct or larger supply, Beta LifeScience can evaluate custom viral-antigen production from sequence review through expression, purification and an assay-aligned QC plan. Project planning may include:

strain, serotype, variant and sequence review;
full-length protein, domain or fragment design;
bacterial, yeast, insect or mammalian expression evaluation;
His, Fc, Avi or other tag-position planning;
optional biotinylation or another requested labeling route;
formulation and concentration review for conjugation or strip use;
purity, identity, aggregation and endotoxin requirements;
pilot production followed by bulk scale-up; and
antibody-binding or application-specific testing where feasible.

Available formats, QC methods, quantities, lead times and functional tests are defined during technical review and confirmed in the quotation.

Need a strain-specific viral antigen?

Share your target, accession, construct, expression host, tag, quantity and QC requirements. Beta LifeScience can evaluate catalog, semi-custom and full-custom production options.

Request a Feasibility Review

Decide Whether the Antigen Is the Analyte or the Capture Reagent

Antigen-detection sandwich LFA

In a sandwich design, the sample’s viral antigen is captured between two antibodies recognizing compatible epitopes. Recombinant antigen supports pair ranking, dose-response work, controls and high-concentration testing. Confirm promising pairs against native viral antigen in representative negative and positive matrices before fixing the strip design.

Antibody-detection or serology LFA

In serology formats, recombinant antigen binds specimen antibodies. It may be placed on the test line, coupled to particles or used in a double-antigen format; density, orientation and conjugation affect epitope access. A conserved antigen may support broad detection, while a strain- or serotype-specific region may improve discrimination. Test related antigens early for cross-reactivity. The strip architecture, sample pad, conjugate pad, nitrocellulose membrane, test and control lines work as one system. Recognition reagents, reporter labels, membrane properties and fluid movement collectively influence lateral-flow performance (Koczula and Gallot ta, 2016).

Antigen Is the Analyte or the Capture Reagent

Choose the Viral Target, Strain and Construct

Target protein

Choose a target with the required abundance, accessibility and immune recognition. Nucleocapsid or capsid proteins may offer abundant internal targets for antigen detection. Surface glycoproteins can present conformational and glycan-dependent epitopes useful for serology or neutralizing-antibody research. Nonstructural proteins such as NS1 can provide secreted or circulating targets in selected infections.

Strain, serotype and variant

State the reference accession, strain, clade, serotype or variant rather than only the virus name. For influenza, define HA subtype and strain; for dengue, define desired serotype coverage; for SARS-CoV-2, specify the sequence and whether conserved or variant-sensitive binding is required.

Full length, domain or fragment

Fragments can focus recognition on a selected region. Full-length constructs can preserve more conformational epitopes but add folding, glycosylation or oligomerization requirements.

Match the Expression Host to Epitope Requirements

Expression host	Potential advantage	LFA-specific consideration
E. coli	Efficient production of many soluble, non-glycosylated antigens	Confirm folding, solubility, endotoxin and whether glycosylation-dependent epitopes are required
Yeast	Scalable secretion and eukaryotic folding for suitable proteins	Glycosylation can differ from mammalian patterns
Insect cells	Useful for many viral glycoproteins and larger constructs	Verify glycan, cleavage and oligomeric requirements
Mammalian cells	Supports mammalian-type folding, disulfides and processing	Higher complexity may affect yield, price and timeline

Host choice should be evaluated experimentally. An E. coli-derived capsid antigen may perform well in a linear-epitope assay, while a spike or envelope protein may need a eukaryotic system to preserve conformation.

Evaluate Tags, Labeling and Conjugation Compatibility

Affinity tags help purification and oriented capture. Confirm that antibodies do not recognize the tag or fusion partner, and align tags across comparison antigens where feasible. Gold nanoparticles, colored latex, fluorescent particles and other reporters can respond differently to protein charge, hydrophobicity and aggregation. Before committing to bulk antigen, test:

passive adsorption versus covalent or affinity-based coupling;
protein-to-particle ratio;
conjugate stability and release from the pad;
signal intensity and background on the selected membrane;
buffer pH, salt, blockers, surfactants and preservatives; and
accelerated and real-time stability under the intended storage format.

Evaluate Tags, Labeling and Conjugation Compatibility

Build a Cross-Reactivity Panel Early

Build a cross-reactivity panel before fixing antibody pairs and constructs. Include:

related viruses within the same family or genus;
multiple strains, clades or serotypes of the target virus;
conserved and variable antigen regions;
common specimen components and potentially interfering proteins; and
the same affinity tag on unrelated proteins to detect tag-directed binding.

For dengue and Zika projects, include both viruses when the selected antigen contains conserved flavivirus epitopes. For influenza, compare relevant A and B strains. Cross-reactivity observed with purified proteins should be followed by testing in representative specimen matrices. This article remains focused on nitrocellulose strips, test-line immobilization, reporter-particle coupling, conjugate-pad release, flow time, hook effect and strip stability. For bead-based or multi-analyte antibody profiling, see Recombinant Viral Antigens for Multiplex Serology Assays.

Define QC for Lateral-Flow Antigen Selection

QC item	Question it answers	Buying guidance
Sequence and intact identity	Is the supplied construct the requested antigen?	Confirm accession, strain, boundaries and tag
SDS-PAGE or HPLC purity	Is the preparation sufficiently pure for the intended stage?	Request the method and lot-specific result
SEC or another aggregation assessment	Is the antigen predominantly monomeric or in the intended assembly state?	Align the acceptance criterion with conjugation behavior
Antibody-binding test	Do the selected antibodies recognize the antigen?	Test both capture and detection reagents where feasible
Protein concentration	Is loading comparable across candidates and lots?	Confirm method and whether the value represents total or active protein
Endotoxin	Is the material compatible with cell-based follow-up work?	Set an application-appropriate specification
Formulation	Will buffer components interfere with labeling or flow?	Review carrier protein, glycerol, detergent, reductant and preservatives

An ELISA-positive antigen is not automatically optimized for a lateral-flow strip. Membrane adsorption, capillary flow, drying, conjugate release and short reaction time create a different environment. Evaluate the material on the intended platform before defining final acceptance criteria.

Optimize Analytical Controls and Prototype Performance

Use an antigen dilution series to compare pairs and define the working range. Include blank matrix, unrelated and related viral antigens, plus a formulation control. Interpret test-line signal with background, control-line performance and flow time. Evaluate high concentrations for prozone or hook behavior, where excess analyte can weaken a sandwich signal. Assess repeatability across strips, days, operators and antigen lots. Recombinant antigen supports controlled analytical studies but does not establish clinical sensitivity or specificity by itself. Those claims require appropriately designed studies using the intended specimen population, reference method and applicable regulatory framework.

Should You Choose Catalog, Semi-Custom or Full-Custom Production?

Choose a catalog product when its strain, construct, tag and host fit the experiment. The viral antigen collection provides a starting point for comparing available targets. Consider semi-custom protein production when an existing antigen or validated platform needs a different tag, buffer, concentration, packaging, quantity or QC package. Use full-custom protein expression for a new viral sequence, construct, host, purification route or application-specific requirement.

What Determines Pricing and Timeline?

Pricing depends on construct size, expression host, folding and glycosylation, target yield, purification difficulty, labeling, formulation, analytical testing, number of variants and final quantity. A simple bacterial fragment may require a different workflow from a mammalian-expressed oligomeric glycoprotein. Project-specific evaluation allows the pilot scope, production route, QC package, deliverables and scale-up plan to be defined before quotation. For long-term LFA development, state any single-production-lot, reserved material or future bridging need for written feasibility confirmation.

Information to Include in a Quote Request

Virus: target, strain, clade, serotype, variant and reference accession.
Construct: full length or residue boundaries, mutations, oligomerization and processing requirements.
Assay: antigen-detection or antibody-detection LFA, antibody pair, specimen type and reporter.
Format: expression host, tag, tag position, labeling, formulation and concentration.
Quantity: pilot amount, final scale, number of variants and expected repeat orders.
QC: purity, identity, aggregation, endotoxin, antibody binding and predefined acceptance criteria.

FAQs

Which viral antigen is best for a lateral-flow assay?

The best antigen matches the intended analyte, strain coverage and assay format. Compare target abundance, epitope conservation, construct boundaries, folding and recognition by the selected antibodies.

Can recombinant antigen be used as a positive control?

Yes, it can support analytical development when concentration, formulation and traceability are defined. A recombinant control does not replace representative clinical or field specimens for performance evaluation.

Do viral glycoproteins require mammalian expression?

Mammalian expression should be prioritized for evaluation when mammalian-type folding or glycosylation is important to antibody recognition. Other hosts may be suitable for linear epitopes or less complex constructs.

Should I choose full-length antigen or a fragment?

A fragment can focus the assay on selected epitopes and simplify production. Full-length material may preserve a broader epitope set; compare both when the recognition requirement is uncertain.

Why test more than one antigen lot?

Lot bridging helps confirm that purity, aggregation, concentration and antibody recognition remain within the assay’s acceptance criteria before extended production.

How can I order a custom recombinant viral antigen?

Submit the sequence, strain, construct, host, tag, LFA format, quantity and QC expectations through the project evaluation form. Feasibility, deliverables, pricing and lead time can then be defined in a customized quotation.

Conclusion:

Share the viral target, strain or serotype, sequence boundaries, expression preference, lateral-flow format, antibody pair, quantity and QC needs. Beta LifeScience can evaluate catalog, semi-custom and full-custom routes and prepare a customized antigen-production proposal.

Submit Your Viral Antigen Project