[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"$fxLN3MUwXCdr5RPjwZYIDpOj8CHyjOmngWTgoKXPtZbg":3,"$ffIts7zWdpJ06dZ4QBjKrZLMp-98ZZPVPnMJ8jCfjxMI":32,"$f3Ft0rKFJHppdzE-vuveecxx1BUcg9iOlMLtyzf_MJDg":80},[4,8,12,16,20,24,28],{"title":5,"slug":6,"path":7},"About Microbeonline.com","about-microbeonline-com","\u002Fabout-microbeonline-com\u002F",{"title":9,"slug":10,"path":11},"About Me","about-me","\u002Fabout-microbeonline-com\u002Fabout-me\u002F",{"title":13,"slug":14,"path":15},"Advertise with Us","advertise-us","\u002Fadvertise-us\u002F",{"title":17,"slug":18,"path":19},"Privacy Policy","privacy-policy","\u002Fprivacy-policy\u002F",{"title":21,"slug":22,"path":23},"Abbreviations","abbreviations","\u002Fabbreviations\u002F",{"title":25,"slug":26,"path":27},"Microbes","microbes","\u002Fmicrobes\u002F",{"title":29,"slug":30,"path":31},"Books","recommended-books","\u002Frecommended-books\u002F",{"type":33,"data":34},"blog",{"slug":35,"title":36,"description":36,"seoTitle":37,"seoDescription":37,"author":38,"createdDate":39,"lastUpdatedDate":40,"draft":41,"category":42,"image":37,"body":43,"faq":44,"tags":45,"related":47},"immunochromatography-principle-application","Immunochromatography\u002F Lateral Flow Immunoassay: Principle and Uses",null,"Acharya Tankeshwar","2020-03-25","2026-07-05",false,"lab-equipment","Immunochromatography, also known as lateral flow immunoassay, is a combination of chromatography and immunoassay. This technology is in use for a wide array of tests for clinical, veterinary, and industrial applications.\n\nDepending on the assay, either antigen (for detection of antibody) or antibodies (for detection of antigens) are immobilized on a nitrocellulose membrane in discreet spots in a cartridge device. Following antibody or antigen capture and a flow-through wash step, the sequential addition of an enzyme-labeled conjugate and substrate results in the appearance of a colored reaction product directly on the membrane.\n\nA typical immunochromatographic test strip consists of\n\n1. an **absorbent pad** onto which specimen is applied,\n2. a **conjugate or reagent pad** that contains antibodies specific to the target analyte conjugated to colored particles (i.e., colloidal gold particles or latex microspheres),\n3. a reaction membrane onto which anti target analyte antibodies are immobilized in a line across the membrane as a **capture zone or test line**,\n4. a **control zone** containing antibodies specific for the conjugate antibodies, and\n5. a waste reservoir composed of another **absorbent pad (wick assembly)** designed to draw the sample across the reaction membrane by capillary action.\n\n![Immunochromatographic test strip - Typical configuration of a lateral flow immunoassay test strip](https:\u002F\u002Fassets.microbeonline.com\u002Fblogs\u002FImmunochromatographic-design.png)Figure: Typical configuration of a lateral flow immunoassay test strip\n\nThe components of the strip are fixed to an inert backing material and may be formatted as a simple dipstick or inside a plastic casing with a sample port and a reaction window showing the **capture (test)** and **control zones**.\n\n> Rapid diagnostic tests or RDTs are lateral flow immuno-chromatographic antigen tests, which rely on the capture of dye-labeled antibodies to produce a visible band on a strip of nitrocellulose, often encased in a plastic housing, referred to as cassettes. RDTs are also available for the detection of antibodies.\n\nA number of variations of immunochromatographic or lateral flow immunoassays have been developed into commercial products, but they all operate according to the same basic principles.\n\n### Principle (for the detection of Antigen)\n\nLateral flow immunoassays used in clinical microbiology laboratories are usually double-antibody sandwich assays. For the detection of antigens, the **capture zone** (test line) on the membrane **contains immobilized antibodies**.\n\nThe specimen (e.g., serum, urine) containing the antigen to be detected is placed on the sample pad, which soaks up the specimen fluid. The fluid then migrates to the conjugate pad, which contains conjugated antibodies (conjugated with gold, colored latex, or a chromophore) directed against the antigen. Here, the antigen-antibody-conjugate complex is formed. Ag-Ab complex continues to migrate across the membrane until it reaches the capture zone where the complex will bind to immobilized antibodies. As more and more Ag-Ab complexes are captured at the “test” line, the line becomes visible on the membrane.\n\n![Lateral Flow Immunoassay](https:\u002F\u002Fassets.microbeonline.com\u002Fblogs\u002FLateral-flow-assay-architecture.png)Figure: Lateral Flow Immunoassay\n\nThe sample then migrates further along the strip until it reaches the **control zone** where excess conjugate binds and produces a **second visible line (control line)** on the membrane. This control line indicates that the sample has migrated across the membrane as intended.\n\nAntibodies that are not antigen-specific or conjugated antibodies that are not complexed with antigen are not captured in the test line and continue to migrate toward the **control line**. The control line is composed of immobilized antibodies directed against immunoglobulin. As more and more uncomplexed antibody passes over the “control” line, the uncomplexed antibodies are captured and become visible at the “control” line. The presence of a “control” line only indicates that the test was performed properly.\n\n**Interpretation of test results**\n\n1. **Positive result**: A clear line in the control zone and the test area on the membrane.\n2. **Negative result**: A single line in the control zone.\n3. **Invalid:** A single line in the test area without a corresponding control line\n\n### Applications of Lateral Flow Immunoassay\n\n![](https:\u002F\u002Fassets.microbeonline.com\u002Fblogs\u002Fbinax-now-influenza.jpg)Immunochromatographic methods are widely used in clinical practice for;\n\n1. Detection of toxins\n2. Pregnancy tests- detection of human chorionic gonadotropin (hCG)\n3. Diagnosis of parasitic infections\n   1. Malaria: Malaria- detect specific antigens (Plasmodium lactate dehydrogenase, Plasmodium aldolase, and *P. falciparum* histidine-rich protein-2) produced by malaria parasites in the blood of infected individuals.\n   2. *G. lamblia* and *Cryptosporidium parvum* (ImmunoCardSTAT! *Cryptosporidium\u002FGiardia*)\n   3. *G.lamblia, E. histolytica\u002FE. dispar*, and *C. parvum* on fecal specimen (Triage Micro Parasite Panel)\n4. Diagnosis of bacterial infections\n   1. *Mycoplasma pneumoniae*(ImmunoCard Mycoplasma, which detects *Mycoplasma pneumoniae* specific [IgM](\u002Figm-antibody-structure-properties-functions-clinical-significance\u002F) in serum samples)\n   2. *H. pylori* antigens in stool (ImmunoCardSTAT SpSA)\n   3. *V. cholerae* O1 and O139 from stool specimens\n   4. *Streptococcus p*neumoniae antigen detection in CSF or in urine (Binax NOW *Streptococcus pneumoniae* antigen card)\n5. Diagnosis of viral Infections\n   1. **Antigen detection:** RSV (Binax NOW RSV, Remel Xpect RSV), Rotavirus (ImmunoCardSTAT! Rotavirus), Influenza A\u002FB (BinaxNOW Influenza A & B), Hepatitis B and Hepatitis C infection\n   2. **Antibodies detection:** Detection of HIV-1 and HIV-2 antibodies (OraQuick Advance Rapid HIV-1\u002F2 antibody test, Reveal G4 Rapid HIV-1 antibody test, Multispot HIV-1\u002FHIV-2 Rapid Test, etc)\n\n### Advantages\n\n- Commercially available and low cost (compared with EIA, Immunofluorescence, or [RIA](\u002Fradioimmunoassay-principle-use-limitation\u002F))\n- Comparable or better sensitivity and specificity than other well-established methods\n- Rapid test\n- Requirement of small sample volume\n- Easy to perform (no sample pre-treatment required in most of the cases)\n- Simple and user-friendly (to perform as well as to interpret test results)\n- Can be used in the field or rural settings: stability over a wide range of environmental conditions and a very long shelf life.\n\n### Limitations\n\n- Mostly qualitative or semi-quantitative\n- Most of the devices can detect more than one or two analytes simultaneously\n\n**Reference and further reading**\n\n- Cherian Sebastian et al. Immunochromatography: Formats and Applications.Indo American Journal of Pharmaceutical Research.2016:6(07).\n- [Koneman’s Color Atlas and Textbook of Diagnostic Microbiology](https:\u002F\u002Famzn.to\u002F2vRkUvk)",[],[46],"chromatography",[48,55,61,67,73],{"slug":49,"title":50,"description":50,"seoTitle":37,"seoDescription":37,"author":51,"createdDate":52,"lastUpdatedDate":40,"draft":41,"category":42,"image":37,"faq":53,"tags":54},"hplc-high-performance-liquid-chromatography","High-Performance Liquid Chromatography (HPLC)","Sushmita Baniya","2022-07-01",[],[46],{"slug":56,"title":57,"description":57,"seoTitle":37,"seoDescription":37,"author":51,"createdDate":58,"lastUpdatedDate":40,"draft":41,"category":42,"image":37,"faq":59,"tags":60},"gas-chromatography-gc-principle-parts-and-uses","Gas Chromatography (GC): Principle, Parts and Uses","2022-06-15",[],[46],{"slug":62,"title":63,"description":63,"seoTitle":37,"seoDescription":37,"author":51,"createdDate":64,"lastUpdatedDate":40,"draft":41,"category":42,"image":37,"faq":65,"tags":66},"gel-filtration-chromatography","Gel Filtration Chromatography","2022-05-19",[],[46],{"slug":68,"title":69,"description":69,"seoTitle":37,"seoDescription":37,"author":51,"createdDate":70,"lastUpdatedDate":40,"draft":41,"category":42,"image":37,"faq":71,"tags":72},"thin-layer-chromatography","Thin Layer Chromatography (TLC): Principle, Procedure, and Applications","2022-05-17",[],[46],{"slug":74,"title":75,"description":75,"seoTitle":37,"seoDescription":37,"author":76,"createdDate":77,"lastUpdatedDate":40,"draft":41,"category":42,"image":37,"faq":78,"tags":79},"chromatography-an-overview","Chromatography: An Overview","Ashma Shrestha","2022-05-15",[],[46],[81,87,93,97,101,105,110,115,119,123],{"slug":82,"name":38,"description":83,"image":84,"body":85,"postCount":86},"acharya-tankeshwar","Editor-in-chief","https:\u002F\u002Fassets.microbeonline.com\u002Fauthors\u002Ftankeshwar-acharya-author-microbeonline.jpg","***Tankeshwar Acharya, MSc (Medical Microbiology)***\n\n*Tankeshwar Acharya is an Assistant Professor in the Department of Microbiology at Patan Academy of Health Sciences (PAHS), Nepal, where he has been teaching and practicing clinical microbiology for over 14 years. He is the founder of Microbe Online, one of the leading free microbiology education resources on the web, covering bacteriology, mycology, parasitology, immunology, and clinical laboratory diagnostics written from direct experience in both the classroom and the diagnostic laboratory.*",433,{"slug":88,"name":76,"description":89,"image":90,"body":91,"postCount":92},"ashma-shrestha","SEO Copywriter and Science Communicator\nKathmandu, Nepal","https:\u002F\u002Fassets.microbeonline.com\u002Fauthors\u002Fashma-shrestha.png","Ashma Shrestha holds a Master of Science in Medical Microbiology from the Institute of Science and Technology (IOST), Tribhuvan University, Nepal, where she developed a strong foundation in virology, molecular biology, and diagnostic microbiology.\n\nShe now works as an SEO Copywriter at Resolution Digital, where she combines her scientific training with research-driven content strategy. She is certified in Google Analytics and Google Business Profile (GBP), and brings a data-informed approach to science communication writing content that is not only accurate but structured to reach and serve the students who need it most.\n\nAt microbeonline, Ashma contributes articles primarily in virology and molecular biology, areas she finds most compelling for their mechanistic depth and their growing clinical relevance. Her writing reflects the same standard the site is built on: factual rigor, clear explanation of the *why* behind microbiology concepts, and content that helps students move from memorization to genuine understanding.\n\nShe is passionate about making complex microbiological concepts accessible without sacrificing accuracy; a skill that sits at the intersection of her scientific training and her professional work in content and SEO.",81,{"slug":94,"name":51,"description":95,"image":37,"body":37,"postCount":96},"sushmita-baniya","Author \u002F Contributor",32,{"slug":98,"name":99,"description":95,"image":37,"body":37,"postCount":100},"samikshya-acharya","Samikshya Acharya",20,{"slug":102,"name":103,"description":95,"image":37,"body":37,"postCount":104},"alisha-tripathi","Alisha Tripathi",6,{"slug":106,"name":107,"description":108,"image":37,"body":37,"postCount":109},"aastha-shrestha","Aastha Shrestha"," Author \u002F Contributor",10,{"slug":111,"name":112,"description":113,"image":37,"body":37,"postCount":114},"guest-author","Guest Author","Guest Author \u002F Contributor",2,{"slug":116,"name":117,"description":95,"image":37,"body":37,"postCount":118},"srijana-khanal","Srijana Khanal",18,{"slug":120,"name":121,"description":113,"image":37,"body":37,"postCount":122},"dr-poonam-acharya","Dr. Poonam Acharya",1,{"slug":124,"name":125,"description":95,"image":37,"body":126,"postCount":127},"nisha-rijal","Nisha Rijal","**Nisha Rijal** is a microbiologist and quality assurance specialist. She served for nearly 12 years as a microbiologist at the National Public Health Laboratory (NPHL), Nepal's national reference laboratory, and continues to work as a consultant microbiologist in international public health organization. ",51]