[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"$fxLN3MUwXCdr5RPjwZYIDpOj8CHyjOmngWTgoKXPtZbg":3,"$f1jJUpR8FfPVPBp2wMBrePfTIb4r9F9NVmbTfteTZxbo":32,"$f3Ft0rKFJHppdzE-vuveecxx1BUcg9iOlMLtyzf_MJDg":47},[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":46},"antibody-affinity-vs-antibody-avidity","Antibody Affinity vs. Antibody Avidity",null,"Acharya Tankeshwar","2022-05-21","2025-12-29",false,"immunology","Antigens and antibodies bind by weak forces such as hydrogen bonds, ionic bonds, hydrophobic interactions, and van der Waal’s forces rather than covalent bonds. The strength of this noncovalent interaction between a single antigen-binding site on an antibody and the single epitope is the **affinity** of this antibody for that epitope.\n\n![Binding of epitope of an antigen with antigen binding site of an antibody - Interaction between antibody and antigen (Image source-Ref-2)](https:\u002F\u002Fassets.microbeonline.com\u002Fblogs\u002FBinding-of-antibody-with-antigen.png)Figure: Interaction between antibody and antigen (Image source-Ref-2)\n\n**Antibody affinity** is proportionate to the fit of the antigen with its antibody-combining site. Low-affinity antibodies bind antigen weakly and tend to dissociate readily, whereas high-affinity antibodies bind antigen more tightly and remain bound longer.\n\n> One crucial effect of booster doses of vaccines is to improve antibody binding by enhancing the affinity maturation process.\n\nThe affinity of [antibodies](\u002Fimmunoglobulin-e-ige-antibodies\u002F) for the [antigen ](\u002Fantigen-structure-types-factors-affecting-immunogenicity\u002F)increases with each successive exposure, known as **affinity maturation**. Antibody binding improves because mutations occur in the hypervariable region of the DNA that encodes the antigen-binding site (a process called **somatic hypermutation**). Some of those [mutations](\u002Fmutation\u002F) result in the formation of plasma cells with better antigen-binding sites. Follicular dendritic cells and follicular helper T cells select only those plasma cells with improved antigen-binding sites for clonal expansion.\n\nSecreted [pentameric IgM](\u002Figm-antibody-structure-properties-functions-clinical-significance\u002F) has the highest avidity of the immunoglobulins as its interaction with antigen can involve all 10 of its antigen-binding sites. Because of this reason, despite having a lower affinity than [IgG](\u002Figg-antibody-structure-subclasses-functions-and-clinical-significance\u002F), IgM can bind antigens effectively.\n\n> Antibody avidity incorporates the affinity of multiple antigen-binding sites.\n\nThe affinity at one binding site does not always reflect the true strength of the [antigen-antibody interaction](\u002Fantigen-antibody-reactions\u002F). The avidity of an antibody is a better measure of its binding capacity within biological systems than the affinity of its binding sites.\n\nWhen complex antigens containing multiple, repeating [epitopes](\u002Fepitope\u002F) are mixed with antibodies containing multiple binding sites, the interaction of an antibody molecule with an antigen molecule at one site will increase the probability of reaction between those two molecules at a second site. The combined binding strength of such multiple interactions between a multivalent antibody and antigen is called the avidity.\n\n![IgG has higher affinity but IgM has higher avidity because of its pentameric nature. - Each IgG antigen-binding site typically has a high affinity for its target. IgM typically has low-affinity antigen-binding sites, but the combined strength of all 10 sites (avidity) is high. Imagesource](https:\u002F\u002Fassets.microbeonline.com\u002Fblogs\u002FAntibody-affinity-vs-antibody-avidity.jpg)Figure: Each IgG antigen-binding site typically has a high affinity for its target. IgM typically has low-affinity antigen-binding sites, but the combined strength of all 10 sites (avidity) is high. Imagesource\n\nIgM often has a lower affinity than IgG, but the high avidity of IgM, resulting from its higher valence, enables it to bind antigens effectively. High avidity compensates for its low affinity.\n\n**References and further readings**\n\n1. [Cellular and Molecular Immunology, 9th Edition](https:\u002F\u002Famzn.to\u002F2Ofk9Rv)\n2. [Kuby Immunology, 8th Edition](https:\u002F\u002Famzn.to\u002F2TXGUOX)\n3. [Roitt’s Essential Immunology, 13th Edition](https:\u002F\u002Famzn.to\u002F2OdRNal)",[],[],[],[48,54,61,66,70,74,79,84,88,92],{"slug":49,"name":38,"description":50,"image":51,"body":52,"postCount":53},"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":55,"name":56,"description":57,"image":58,"body":59,"postCount":60},"ashma-shrestha","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":62,"name":63,"description":64,"image":37,"body":37,"postCount":65},"sushmita-baniya","Sushmita Baniya","Author \u002F Contributor",32,{"slug":67,"name":68,"description":64,"image":37,"body":37,"postCount":69},"samikshya-acharya","Samikshya Acharya",20,{"slug":71,"name":72,"description":64,"image":37,"body":37,"postCount":73},"alisha-tripathi","Alisha Tripathi",6,{"slug":75,"name":76,"description":77,"image":37,"body":37,"postCount":78},"aastha-shrestha","Aastha Shrestha"," Author \u002F Contributor",10,{"slug":80,"name":81,"description":82,"image":37,"body":37,"postCount":83},"guest-author","Guest Author","Guest Author \u002F Contributor",2,{"slug":85,"name":86,"description":64,"image":37,"body":37,"postCount":87},"srijana-khanal","Srijana Khanal",18,{"slug":89,"name":90,"description":82,"image":37,"body":37,"postCount":91},"dr-poonam-acharya","Dr. Poonam Acharya",1,{"slug":93,"name":94,"description":64,"image":37,"body":95,"postCount":96},"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]