Qualitative Detection of HIV-1/HIV-2 Antibodies and p24 Antigen in 15 Minutes
A 4th generation HIV Ag/Ab combo test is a rapid diagnostic device that detects two different HIV biomarkers in a single cassette: antibodies to HIV-1 and HIV-2, and the HIV p24 core antigen. Detection of antibodies to HIV-1, HIV-2, and p24 antigen in serum, plasma, or whole blood is the most efficient and common way to determine whether an individual has been exposed to HIV and to screen blood and blood products.
Earlier-generation antibody-only rapid tests can miss recently infected individuals during the window period — the interval after exposure but before the immune system has produced detectable antibodies, typically 3 to 12 weeks. The p24 core antigen becomes detectable in blood earlier than antibodies during acute infection, so combining antigen and antibody detection on separate test lines narrows this diagnostic gap compared to antibody-only formats.
HIV-1 and HIV-2 are genetically distinct but show strong antigenic cross-reactivity, and most HIV-2 positive sera can be identified using HIV-1-based serological tests. The Sekbio HIV Ag/Ab Combo Rapid Test Device (REF SEK-G102) is a membrane-based immunoassay pre-coated with recombinant HIV-1/HIV-2 antigens and anti-p24 antibody in two separate test line regions, allowing a single 15-minute test to screen for both markers.
The Sekbio HIV Ag/Ab Combo Human Immunodeficiency Virus Rapid Test Device (REF SEK-G102) is a single-use, qualitative, membrane-based colloidal gold lateral flow immunoassay for the detection of antibodies to HIV-1, HIV-2, and HIV p24 antigen in whole blood, serum, or plasma specimens.
The membrane is pre-coated with recombinant HIV antigen and anti-p24 antibody in two separate test line regions, T1 and T2. The T1 line is coated with HIV-1 and HIV-2 recombinant antigen and captures anti-HIV antibodies present in the specimen. The T2 line is coated with anti-p24 monoclonal antibody and captures p24 antigen present in the specimen. If the specimen contains antibodies to HIV-1 or HIV-2, a colored line appears at T1; if the specimen contains p24 antigen, colored lines appear at both T1 and T2. Either outcome indicates a positive result. A colored control line (C) always appears in a valid test, confirming that the proper specimen volume was added and membrane wicking occurred.
Results are read visually at 15 minutes. No laboratory equipment, reader, cold chain, or electrical supply is required during testing.
Suitable for VCT clinics, blood screening laboratories, and mobile/community testing programs.
Allow all kit components and the specimen to reach room temperature (18–26 °C). Remove the test device from the foil pouch and place it on a clean, dry, level surface.
Hold the dropper vertically and transfer 1 drop of specimen (~30 µL) to the sample well (S), then add 1 drop of sample diluent (~30 µL). Start the timer immediately.
Wait for the colored line(s) to appear and read results at exactly 15 minutes. Do not read results after 20 minutes.
Once the foil pouch is opened, the single-use test should be used within 1 hour under low environmental humidity (RH ≤ 70%).
The cassette has three possible line positions: Control (C), Test 1 (T1, antibody), and Test 2 (T2, antigen). The Control line must always appear for a valid test.
Only the Control line (C) is visible. Neither HIV-1/HIV-2 antibodies nor p24 antigen were detected at or above the assay's detection threshold.
Control (C) and Test 1 (T1) lines visible. Antibodies to HIV-1 and/or HIV-2 detected. Confirmatory testing per local testing algorithm is recommended.
Control (C), Test 1 (T1), and Test 2 (T2) lines all visible. HIV p24 antigen detected, alongside HIV-1/HIV-2 antibody reactivity. Confirmatory testing per local testing algorithm is recommended.
Control line (C) absent. The result is invalid regardless of the test line pattern. Review the procedure and repeat with a new device. If the problem persists, contact your distributor.
Important: This device is a screening test intended for professional in vitro diagnostic use only. A reactive (positive) result does not confirm HIV infection — it must be followed by confirmatory testing according to the applicable national HIV testing algorithm. Do not use the device after its expiration date, and do not use if the foil pouch is damaged.
Separate T1 and T2 test lines allow the assay to distinguish, in a single cassette, whether a reactive result is driven by antibody seroconversion, active p24 antigenemia, or both.
| Test Line | Coating Reagent | Detects | Clinical Significance |
|---|---|---|---|
| T1 | Recombinant HIV-1 & HIV-2 antigen | ✓ Anti-HIV Antibodies | Marks seroconversion; typically detectable 3–12 weeks post-exposure |
| T2 | Anti-p24 monoclonal antibody | ✓ HIV p24 Core Antigen | Marks active viral replication; detectable earlier than antibodies during acute infection |
| C (Control) | Procedural control reagent | N/A | Confirms adequate specimen volume and correct membrane wicking |
| HIV-1 and HIV-2 show strong antigenic cross-reactivity; most HIV-2 positive sera are identified by HIV-1-based serological assays. The device does not distinguish HIV-1 from HIV-2 reactivity at T1. | |||
Independent T1 (antibody) and T2 (p24 antigen) test lines in one cassette narrow the diagnostic window period compared with antibody-only 3rd generation rapid tests.
705 of 705 reactive specimens correctly identified across HIV-1 plasma, serum, whole blood, finger-prick blood, p24 antigen-positive plasma, and HIV-2 plasma on the CHINA NMPA reference panel.
From whole blood, serum, or plasma to visual result in 15 minutes. No laboratory equipment, electricity, or specialist technician required.
No interference from ascorbic acid, hemoglobin, bilirubin, acetaminophen, aspirin, caffeine, or methanol at tested concentrations, and no cross-reactivity with HCV, syphilis, HBsAg, or rheumatoid factor-positive specimens.
Accepts whole blood (including finger-prick capillary blood), serum, or plasma — supporting both laboratory-based screening and decentralized community/mobile testing.
Available for OEM and private label supply. Custom branding, multilingual IFU, and packaging design supported. Contact info@sekbio.com for a quotation.
Data summarized from the product package insert, evaluated across three independent production lots against the CHINA NMPA reference panel.
Reactive specimens were collected from CDC-affiliated centers and hospitals (HIV-1) and sourced from SeraCare US and Biomex GmbH (HIV-2), then tested against the CHINA NMPA reference panel.
| Specimen Type | Positive Result | Total Specimens | Sensitivity |
|---|---|---|---|
| HIV-1 positive plasma | 483 | 483 | 100% |
| HIV-1 positive serum | 64 | 64 | 100% |
| HIV-1 positive whole blood | 100 | 100 | 100% |
| HIV p24 antigen positive plasma | 13 | 13 | 100% |
| HIV-1 positive finger blood | 25 | 25 | 100% |
| HIV-2 positive plasma | 20 | 20 | 100% |
| Total | 705 | 705 | 100% |
Specimens confirmed negative for HIV but positive for potentially interfering conditions or analytes were tested to evaluate specificity.
| Specimen Category | Negative Result | Total Specimens | Specificity |
|---|---|---|---|
| Bilirubin < 146.7 µmol/L | 10 | 10 | 100% |
| Triglyceride < 8.74 mmol/L | 10 | 10 | 100% |
| Hemolysis, Hb > 6.5 g/L | 19 | 20 | 95% |
| Anti-HCV positive | 20 | 20 | 100% |
| Anti-HAV positive | 10 | 10 | 100% |
| HBsAg positive | 20 | 20 | 100% |
| Anti-HEV positive | 20 | 20 | 100% |
| Anti-HTLV I/II positive | 20 | 20 | 100% |
| Anti-CMV IgM positive | 5 | 5 | 100% |
| Rheumatoid factor positive | 20 | 20 | 100% |
| Total | 154 | 155 | 99.35% |
| The single discordant result occurred in a grossly hemolyzed specimen (Hb > 6.5 g/L); an alternative detection method is recommended for such samples. | |||
Analytes were spiked into negative and low-positive plasma/serum pools at the listed concentrations and tested in triplicate across three lots. Visual interpretation was made at 10 and 20 minutes.
| Analyte | Concentration | Negative Pool Result | Positive Pool Result |
|---|---|---|---|
| Ascorbic acid | 20 mg/dL | Non-reactive | Reactive, unaffected |
| Hemoglobin | 1000 mg/dL | Non-reactive | Reactive, unaffected |
| Bilirubin | 1000 mg/dL | Non-reactive | Reactive, unaffected |
| Gentisic acid | 20 mg/dL | Non-reactive | Reactive, unaffected |
| Acetaminophen | 20 mg/dL | Non-reactive | Reactive, unaffected |
| Acetylsalicylic acid (aspirin) | 20 mg/dL | Non-reactive | Reactive, unaffected |
| Caffeine | 20 mg/dL | Non-reactive | Reactive, unaffected |
| Oxalic acid | 60 mg/dL | Non-reactive | Reactive, unaffected |
| Uric acid | 20 mg/dL | Non-reactive | Reactive, unaffected |
| Methanol | 10% | Non-reactive | Reactive, unaffected |
| No substances showed interference with the test. No difference was observed between results read at 10 minutes and at 20 minutes. | |||
Specimens confirmed by ELISA and clinical diagnosis for the following conditions were tested to evaluate non-specific cross-reactivity, read at 10 and 20 minutes.
| Specimen Category | 10 min | 20 min |
|---|---|---|
| Pregnancy (HCG) samples | Non-reactive | Non-reactive |
| HCV positive samples | Non-reactive | Non-reactive |
| Syphilis positive samples | Non-reactive | Non-reactive |
| HBsAg positive samples | Non-reactive | Non-reactive |
| Mono positive samples | Non-reactive | Non-reactive |
| Lipemic samples | Non-reactive | Non-reactive |
| Icteric samples | Non-reactive | Non-reactive |
| Hemolysis samples | Non-reactive | Non-reactive |
| Rheumatoid factor positive samples | Non-reactive | Non-reactive |
| No cross-reaction was observed with any of the tested conditions at either read time. | ||
High positive (SIH92), medium positive (WB-M), low positive (WB-L1), and negative (041064) specimens were run in 10 replicates across three independent production lots, read visually against a color reference card at 10 and 20 minutes.
| Precision Metric | Plasma | Whole Blood | Conclusion |
|---|---|---|---|
| Intra-lot repeatability (10 reps) | Consistent color grade | Consistent color grade | PASS ✓ |
| Inter-lot reproducibility (3 lots) | Consistent color grade | Consistent color grade | PASS ✓ |
REF SEK-G102 — 25 Tests / Kit
| Component | Quantity | Description |
|---|---|---|
| Test Device | 25 pcs | Colloidal gold LFA cassette, individually sealed in foil pouch with desiccant |
| Sample Diluent | 1 vial | Buffer added after specimen to initiate chromatographic migration |
| Disposable Dropper | 25 pcs | For transferring ~30 µL specimen and ~30 µL diluent to the sample well |
| Package Insert (IFU) | 1 pc | Instructions for Use — multilingual available for OEM orders |
Not included: lancets or venipuncture supplies, gloves, timer, biohazard waste container.
Screen donated whole blood, serum, or plasma for HIV-1/HIV-2 antibodies and p24 antigen prior to transfusion or further processing, as part of a broader blood safety testing algorithm.
Point-of-care format with a 15-minute result and finger-prick whole blood compatibility supports same-visit HIV testing and counseling in clinical and community settings.
No laboratory equipment, electricity, or cold chain required during testing — supporting mobile outreach units, community health workers, and primary care facilities in high HIV-burden regions.
Available for private label and OEM supply with custom branding, IFU localization, and packaging. Competitive MOQ for established IVD distributors and brands.
Export-ready components for IVD distributors and kit assemblers across Sub-Saharan Africa, where HIV testing volume remains among the highest globally.
Certificate of Analysis (CoA), MSDS, and lot traceability records are provided with every OEM shipment to support customs clearance and local registration filings.
Ambient storage (2–30 °C) simplifies logistics to mobile testing units and primary care facilities outside major urban centers.
Instructions for Use and packaging available in English, French, and Arabic, supporting Anglophone, Francophone, and North African distributor markets.
OEM order quantities scaled for regional distributors and kit assemblers building out a local rapid test portfolio, rather than requiring institutional-tender volumes.
Local regulatory registration (e.g., NAFDAC, SAHPRA) remains the responsibility of the importing distributor. Sekbio provides the underlying technical file, panel evaluation data, and manufacturing documentation to support that process.
Active OEM and export supply capability for distributors and kit assemblers across the region. See our full rapid test portfolio for Africa.
IFU, panel evaluation report, quality documentation, and OEM pricing available on request.