Semi-Quantitative Detection of Viral Infection Biomarker MxA in Whole Blood — Result in 15 Minutes
MxA (Myxovirus Resistance Protein A) is a 78 kDa dynamin-like GTPase encoded by the MX1 gene. It is induced specifically by type I interferons (IFN-α, IFN-β) and type III interferons (IFN-λ), which are produced by host cells in direct response to viral — but not bacterial — infection. This mechanistic specificity makes MxA one of the most clinically validated single biomarkers for distinguishing viral from bacterial causes of acute febrile illness.
Three properties make MxA diagnostically ideal: (1) a low basal concentration of less than 15 ng/mL in healthy adults, providing a clear normal baseline; (2) rapid induction within 1–2 hours of viral challenge, enabling early detection; (3) a prolonged half-life of approximately 2.3 days, ensuring the signal persists throughout the acute infection phase and remains detectable across clinical presentation windows.
Numerous prospective clinical studies have demonstrated that elevated MxA in peripheral blood leukocytes or whole blood is a sensitive and specific indicator of acute viral infection, with diagnostic performance superior to traditional inflammatory markers such as CRP and ESR for virus–bacteria differentiation in undifferentiated febrile patients.
The Sekbio MxA Rapid Test Kit (SEK-G088) is a semi-quantitative colloidal gold lateral flow immunoassay for the detection of MxA protein in human whole blood. The test uses an anti-MxA capture antibody pre-coated on the test line and a colloidal gold-conjugated anti-MxA detection antibody on the conjugate pad. MxA in the whole blood sample migrates along the nitrocellulose membrane and is captured at the test line, producing a colored band whose intensity is proportional to MxA concentration.
The kit includes a color reference chart for semi-quantitative result estimation — enabling clinical assessment of MxA levels without a dedicated reader, making it suitable for point-of-care use in outpatient clinics, emergency departments, and resource-limited settings.
Understanding how MxA behaves across infection types is essential for correct clinical interpretation.
Bacterial infections trigger innate immune responses through Toll-like receptors (TLRs) and NF-κB pathways — which do not activate the interferon signaling cascade that induces MxA. As a result, MxA remains below the detection threshold in most bacterial infections even when CRP, procalcitonin, and WBC counts are markedly elevated. This negative predictive value for bacterial etiology is one of MxA's most clinically actionable properties.
| Clinical Scenario | MxA Level | CRP | PCT | Clinical Implication |
|---|---|---|---|---|
| Acute viral URTI (influenza, RSV, rhinovirus) | Mildly elevated or normal | Normal | Viral etiology — antibiotics not indicated | |
| Acute bacterial infection (pneumonia, UTI) | Normal (<15 ng/mL) | Markedly elevated | Elevated | Bacterial etiology — antibiotics indicated |
| Febrile child — undifferentiated illness | Variable | Variable | MxA positivity argues against antibiotic use | |
| COVID-19 (SARS-CoV-2) | Elevated | Variable | Supports viral diagnosis; guides antiviral use | |
| Healthy adult / non-infectious illness | <15 ng/mL (baseline) | Normal | Normal | No active viral infection |
Result available in 15 minutes from sample addition. No laboratory equipment required — visual interpretation with the included color reference chart. Suitable for emergency departments, outpatient clinics, and field settings.
Accepts both venipuncture EDTA blood and fingerstick capillary blood directly. No centrifugation or serum separation required. 30 µL sample volume — achievable from a single fingerstick.
T-line intensity correlates with MxA concentration. The included color reference chart provides semi-quantitative estimation across clinically relevant MxA levels — supporting treatment decisions at the bedside.
Stored at 2°C–30°C — no cold-chain requirements. 18-month shelf life supports inventory management in clinics, pharmacies, and distribution networks across tropical and subtropical markets.
Manufactured under ISO 13485-certified quality management. CE marked for IVD use. Full technical documentation available for regulatory registration in EU, Africa, Southeast Asia, and Middle East markets.
Custom branding on cassette and carton. Multilingual IFU printing. Packaging design services. Minimum order quantities negotiable. Contact Sekbio for volume-based OEM pricing.
Equilibrate all reagents and specimen to room temperature (15°C–30°C) before starting.
Remove the test cassette from the sealed foil pouch and place on a clean, flat, horizontal surface. Use within 1 hour of opening. Allow the cassette and sample treatment solution to reach room temperature.
Using the dropper provided, add 30 µL of whole blood to the specimen well (S), followed immediately by 30 µL of sample treatment solution. Start the timer immediately.
Read the result at exactly 15 minutes. Do not interpret after 20 minutes — results may be unreliable. Compare the T-line intensity to the color reference chart for semi-quantitative estimation.
Any visible color in the Test line (T) region is a positive result, regardless of intensity.
Both C and T bands appear. Elevated MxA detected — consistent with acute viral infection. Compare T-line intensity to the color reference chart for semi-quantitative MxA level estimation. Interpret in conjunction with clinical presentation.
Only C band appears. MxA is below the detection threshold. Consistent with absence of acute viral infection. Does not exclude early-stage infection or viral infection in immunocompromised patients.
No C band appears. Test is invalid regardless of T-line status. Discard result. Review the procedure and repeat with a new cassette. If problem persists, contact your local distributor.
Any shade of color in the T line region should be considered a positive result. Results read after 20 minutes may be unreliable.
Materials required but not provided: specimen collection container, timer, disposable gloves.
Rapid differentiation of viral from bacterial febrile illness at initial patient assessment — guides antibiotic prescribing decisions within the first 15 minutes of patient contact, before laboratory results are available.
Children present frequently with undifferentiated febrile illness where clinical exam alone cannot distinguish viral from bacterial cause. A positive MxA result provides objective support for watchful waiting without antibiotics in otherwise well-appearing children.
During influenza season or respiratory virus outbreaks, MxA positivity supports a viral diagnosis and correlates with the presence of influenza A/B, RSV, rhinovirus, and other respiratory pathogens — informing antiviral therapy decisions.
Room-temperature stability, no equipment requirement, and fingerstick whole blood specimen collection make this test practical for primary care clinics, rural health posts, and low-resource settings where laboratory access is limited.
The Sekbio MxA Rapid Test Kit (SEK-G088) is a semi-quantitative colloidal gold lateral flow immunoassay that detects Myxovirus Resistance Protein A (MxA) in human whole blood within 15 minutes. MxA is a 78 kDa GTPase protein specifically induced by type I and III interferons in response to viral infection. Elevated MxA is a highly specific biomarker for acute viral infection, enabling viral vs. bacterial differentiation at the point of care. The included color reference chart provides semi-quantitative MxA level estimation without requiring a dedicated reader.
MxA is a dynamin-like GTPase encoded by the MX1 gene, induced exclusively by type I interferons (IFN-α, IFN-β) and type III interferons (IFN-λ). These interferons are released in direct response to viral RNA or DNA — not in response to bacterial pathogens. Because bacterial infections activate immune pathways (TLR/NF-κB) that do not trigger interferon signaling, MxA remains below the detection threshold in bacterial infections even when inflammatory markers like CRP and WBC are elevated. This mechanistic specificity for the antiviral interferon axis is what makes MxA a clinically reliable viral-specific biomarker. Basal MxA in healthy adults is <15 ng/mL; levels rise within 1–2 hours of viral challenge and persist for approximately 2.3 days (MxA half-life).
POSITIVE: Both C and T bands appear. Any visible T-line color indicates elevated MxA consistent with acute viral infection. Compare T-line intensity to the color reference chart for semi-quantitative concentration estimation.
NEGATIVE: Only C band appears. MxA is below the detection threshold — consistent with no acute viral infection. A negative result does not exclude early-stage infection or infection in immunocompromised patients.
INVALID: No C band appears. Test is invalid regardless of T-line status. Repeat with a new cassette after reviewing procedure. If repeated invalids occur, contact your distributor.
The MxA Rapid Test (SEK-G088) is validated for whole blood only — either venipuncture EDTA-anticoagulated blood or fingerstick capillary blood. Serum and plasma are not validated sample types and may yield unreliable results. Each test requires 30 µL of whole blood mixed with 30 µL of sample treatment solution. Venipuncture blood may be stored at 2°C–8°C for up to 2 days before testing; fingerstick blood must be tested immediately.
Yes. MxA is one of the most validated single biomarkers for viral vs. bacterial differentiation in febrile patients. Clinical studies demonstrate high sensitivity and specificity for acute viral infection (including influenza A/B, RSV, rhinovirus, COVID-19) across adult and pediatric populations, while MxA remains low in confirmed bacterial infections. A negative MxA result in a febrile patient provides supportive evidence for bacterial etiology and the appropriateness of antibiotic therapy. MxA results must always be interpreted in conjunction with clinical presentation, patient history, and other diagnostic assessments — they do not replace clinical judgment.
Store at 2°C–30°C in a dry location, protected from direct sunlight. Shelf life is 18 months from the date of manufacture. No refrigeration required — room-temperature stable storage throughout. Once the foil pouch is opened, use the cassette within 1 hour. Do not freeze test cassettes. Check the kit label for lot-specific expiration date.
Yes. Sekbio offers full OEM and private label services for the MxA Rapid Test Kit: custom branding on cassettes and outer cartons, multilingual IFU printing, and custom packaging design. Technical documentation packages for CE marking or local regulatory registration in target markets (Africa, Southeast Asia, Middle East, Latin America) are available. Contact info@sekbio.com with your target market, annual volume estimate, and brand requirements for a dedicated OEM quotation.
ISO 13485-certified. CE marked. Available in 25-test kits and bulk OEM supply. Contact Sekbio for pricing, samples, and regulatory documentation.
Sekbio also supplies validated anti-MxA monoclonal antibody pairs for CLIA, ELISA, and lateral flow development — including the same recombinant clones used in the SEK-G088 kit, available as bulk raw material for OEM IVD manufacturers.
View MxA Antibody Products →Explore Sekbio's full rapid test portfolio — covering infectious disease, cardiac markers, hormones, and inflammation biomarkers in colloidal gold and fluorescence lateral flow formats. OEM supply with CE marking documentation support.
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