Questions tagged [antigen]

An antigen is a substance which causes the the body to produce a reaction of the adaptive immune system. Contact of the immune system to antigens results in the production of highly specific (antigen specific) antibodies.

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Why can't SARS-CoV2 antigen lateral flow tests be used for testing animals?

Real use case: Two male neutered Felis catus individuals live in a household where up to three humans live of which all were infected with SARS-CoV2 at the same time, proven by antigen and PCR tests. ...
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Antigen transfer from baby to mother

When considering immunity in babies, the main mechanism that supports their undeveloped immune system is the transfer of antibodies from mother to baby via breastfeeding. Case #1: both baby and mother ...
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What is the significance of an adjuvant to traffic vaccine antigen directly to draining lymph nodes without diffusing into the systemic circulation?

I found the following sentence in the this paper- Safety and immunogenicity of an inactivated SARS-CoV-2 vaccine, BBV152: a double-blind, randomised, phase 1 trial An imidazoquinoline molecule, which ...
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Why are O-antigens and H-antigens on (certain) bacteria called O and H?

Somehow, despite extensive searching, I cannot find an answer.... Does O stand for oxygen and H signify hydrogen?
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Do people with type O- blood have a higher risk for autoimmune diseases?

Recently in my Physiology class, I learned that antigens help the immune system differentiate between the body's own cells and foreign cells. This led me to this question: If people with type O- blood,...
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Boost of Janssen COVID-19 Vaccine increasing Immune Response to Vector

I have been looking for published, or even pre-print, data that evaluates the serological response to a boost of the Janssen COVID-19 Vaccine against the adenoviral vector Ad26 rather than the ...
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Detecting multiple compounds on a lateral flow immunoassay – is this a case of monoclonal vs polyclonal antibodies?

I am working on developing lateral flow immunoassays for drugs of abuse and needed some advice on detecting multiple drug compounds in one immunoassay. As an example, an existing LFIA on the market ...
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Why do T cells have MHC II receptors?

I have seen the answer to this question which says that T cells do not express MHC II proteins which would make sense. However, my textbook "The immune system" by Peter Parham disagrees. It ...
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Are antibodies removed before blood transfusion

I am an O blood group person meaning, I can donate my blood to all as I don't have any Antigen A and B. But my body does contain antibodies A and B right? If they were along with the donor blood, ...
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Sensitivity vs. Limit of Detection of rapid antigen tests

I'm comparing a bunch of SARS-CoV2 rapid antigen tests: Source Columns 4 and 6 list the values for sensitivity and limit of detection (LOD). How come that a test with a several times lower limit of ...
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What is a function-triggering antibody?

I am reading a journal paper on the effect of a neural cell adhesion molecule on neuronal development and in the abstract of this paper I have come across the following: The autophosphorylation and ...
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Can any molecule become a hapten?

Hapten are small-molecules, that can only become immunogenic when conjugated with a carrier protein. I was wondering if all small-molecules can become haptens (eg. by synthetic conjugation). Given ...
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With the 5$ covid19 test - an antigen test - , would trials (most likely) be independent?

Actual question What would typically cause antigen tests to give a false positive or false negative and would these causes be typically independent (if we run the test twice it won't automatically ...
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Easy and cheap antigen/antibody couple

For an application I need to find a cheap antigen and cheap correspondent antibody. The antigen can be literally any molecule that is cheap and potentially easy to produce and with a correspondent ...
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Could there be a pathogen which does not activate an immune response?

In order for the immune system to be stimulated to produce antibodies, there must be a surface protein of the invading pathogen which binds to a receptor on B cell surface somewhat loosely. We need ...
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Are all antibodies against a common antigen identical? [duplicate]

I understand that when some antigen (e.g., virus, bacteria, etc.) is recognized in the body, antibodies specific to this antigen are produced that, in turn, bind to the antigen and effectively ...
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Reasons why this protein is not suitable as an immunogen?

In a paper entitled "Progress and Prospects on Vaccine Development against SARS-CoV-2", the authors write the following in section 2.5: "Compared with S, N, and M protein, E protein is not suitable ...
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Is it possible for virus infected cells to continue to present a self-antigen on the MHC1?

Forgive my ignorance, as I'm new to immunology, however it seems like there would be some amount of positive selective pressure for viruses to develop the ability to continue to present the host's ...
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How are antibodies specific for a disease detected in the blood if everybody produces a different antibody for the same antigen?

To break the title down into parts: There exist serology tests that detect the amount of an antibody (Ab) against a specific pathogen/antigen. Every human produces their own Ab for a specific ...
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How does the immune system find the DNA code for antibodies

There are millions of possible antigens. To respond to each antigen, the immune system must quickly produce an antibody by modifying the DNA of a B cell. I have no idea how this process works, but ...
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Are hormones antigenic?

I have been asked whether hormones are antigenic. I would have to think that the answer is no because they are used as various drugs such as FSH in infertility treatments without the need of ...
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What happens to the molecules of the pathogens after phagocytosis?

For example, what happens when a bacterium gets digested by a macrophage? I suppose that the macrophage produces the presented antigen from leftovers from the digested bacterial particles. What ...
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Are tumor-associated antigens unique to cancerous cells?

Are tumor-associated antigens found only on the membrane of cancerous cells or just over-expressed on the membrane of carcinogenic cells? In other words, are these antigens also found on healthy ...
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What is meant by 'fixing' of an antigen presenting cell?

Can someone please explain what does 'fixing' of an antigen presenting cell mean?
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Can MHC class I be used for presenting peptides of extracellular origin by non-professional APCs?

Wikipedia says that: "The antigens presented by MHC class II are derived from extracellular proteins (not cytosolic as in MHC class I)." So does this mean that MHC class I cannot be used for ...
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Choosing viruses for influenza vaccine

When scientists choose viruses for the influenza vaccine based on biological and clinical data, what indicates that a certain strain will circulate and likely be dominant in a certain season? Does a ...
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How does one predict how large of an effect on antigenic drift a substitution in the amino acid sequence of a surface protein of influenza has?

I know that some amino acid substitutions are more effective in causing antigenic drift than other substitutions based on their location in the 3d structure of the HA protein (proximity to the ...
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Can multiple antibodies bind the same antigen?

Given the size difference between small molecule antigens and antibodies is it ever possible for multiple antibodies to bind to the same antigen if they recognize different domains on that antigen? ...
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Why are vaccines a successful treatment of allergy?

As I understand the answer to Allergic rhinitis vaccine, the vaccine facilitates immune response against the antigen. Given that allergy is an overreaction of the immune system against harmless ...
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CD4 Proteins & Antigen presenting cells

If Helper T-Cells express CD4+ proteins on their surface to bind to MHC Class ll proteins on antigen presenting cells, why do antigen presenting cells also have CD4+ Proteins?
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Vaccines against bacterial endotoxins

Today in class, there was a discussion going on about what part of pathogens(which can act as an antigen) can be used to make vaccines. There was this point where our teacher said that bacterial ...
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Will a sandwich assay work with a GST 26 antibody/protein?

I have a GST 26 kda antibody, and want to use it in a sandwich lateral flow assay. Are there enough epitope regions for both antibodies to bind to the protein?
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Autoimmunity - negative selection of T-cells - APC

Through negative selection of T-cell in the thymus T-cells lose the possibility to react to antigens which are "body own" -> self antigens. Though there are more than just this negative selection for ...
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How does adjuvant enhance the immunogenicity of antigen? [closed]

My question is, How does adjuvant enhance immunogenicity of antigen? I just want to know deeply about it , Any suggestions will be helpful!
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How do scientists discover a new antigen and its epitope?

I've found some database on the internet that list all discovered antigens and their epitopes. So how do scientists discover a new antigen? Do they try to inject them into the body to see if it ...
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Detect which antigen binds to IgE

Assume that a patient has chronic hives (itchy) on the skin. I understand that he has an antigen, which binds to IgE and eventually triggers histamine release, causing an allergic reaction. So is ...
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Are antibodies and hepatitis viruses of similar adaptability?

Antibodies and Hepatitis viruses both have hypervariable regions. Is one more adaptable than the other? Precisely how adaptable are they? I have read that antibodies can be trained to bind to ...
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Do allergens have structural similarities to pathogens?

The conventional popular explanation of allergies is that the immune system confuses allergens with pathogens and reacts to them as such. Is there any merit to this explanation? If so, I would ...
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O-Group names of Salmonella serotypes?

What liposaccharides are represented by the O-group designations of Salmonalla serovars in the Kauffman-White classification scheme? I mean to ask, how do the numbers in a Sal serovar (1, 9, & 12 ...
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How is a T lymphocyte specific to an antigen but not specific to an epitope?

In my immunology notes, it states that B lymphocytes (and other APCs) capture and present antigens to T lymphocytes that is specific for an antigen, but that the T cells do not necessarily recognise ...
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Why does the blood not clump and result in death?

In this question's accepted answer, it is said that the blood type will slowly change to that of the donor's. When the blood in the person is about 50% his own and 50% that of the donor's. i.e, 50% A ...
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Minimum size for a peptide/protein to be immunogenic in human?

What is the minimum size for an (injected) peptide/protein to cause immunogenic response in human? A reference is very helpful, as well. Thanks in advance
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What are blood group determinants? [closed]

I am trying to understand if they are the same as the blood antigens. The books I have tried to read say something about them being the antigens on the surface of the red blood cell.
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Can you Transfer Cancer Between People via Saliva or other Bodily Fluids?

This may sound like a strange question. But could a Cancerous cell be transferred from one person to another from Oral contact e.g. Through Saliva, or other exchange of bodily fluids? I know that ...
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What is cross-immunoreactivity, and how does it impact vaccine development?

What I understand about cross-immunoreactivity is that the antibody induced by one specific antigen is also fairly effective against another antigen. How would this be used for vaccine development? ...
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6 votes
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Can we produce synthetic red blood cells lacking antigens?

I had an idea come to me during Biology class and I immediately asked my teacher, but she couldn't really answer the question, so I'll ask it here. What are the limiting factors in the production of ...
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7 votes
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What is a positive epitope fragment

What is a positive epitope fragment? I found one paper on the subject: COBEpro: a novel system for predicting continuous B-cell epitopes by Michael J. Sweredoski and Pierre Baldi
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How to inhibit formation of specific antibodies (to antisera)?

Is there a way to inhibit an antibody response to a specific antigen using immunosupression? I am interested in reducing the anti-antibody formation to animal antibodies such as murine antibodies in ...
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human anti-mouse antibody

I have heard about human anti-mouse antibodies (HAMAs) and read that HAMAs neutralize murine antibodies, therefore decreasing the effectiveness of those murine antibodies. Is this true that HAMAs ...
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Synthesis of immunoglobulin Fab fragments: Where can I learn about Fab?

I wanted to know the chemical reaction involved in Fab synthesis. I looked everywhere for it. No luck. I know I will find it here. All I know for now is: Fab is a monovalent fragment that is ...
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