The key difference between antigen and pathogen is that antigen is a foreign substance, toxin or a molecule that can stimulate an immune response in order to produce antibodies against it while pathogen is an organism, especially a microbe, that infects our body and causes diseases.
Pathogens are any foreign organisms that cause diseases in host plants and animals. An antigen is a molecule located in the cell wall of bacteria or the coating of organisms. Antigen causes our immune system to produce antibodies against it and protect our body from harmful foreign organisms.
CONTENTS
1. Overview and Key Difference
2. What is an Antigen
3. What is a Pathogen
4. Similarities Between Antigen and Pathogen
5. Side by Side Comparison – Antigen vs Pathogen in Tabular Form
6. Summary
What is an Antigen?
An antigen is a molecule, especially a foreign molecule, that is capable of stimulating an immune response in our body. As a result, our body produces a specific type of antibody against it. Generally, antigens are proteins and polysaccharides located in the cell walls of bacteria or in the coating of other organisms. They may be present in the capsule and flagella of bacteria as well. Once an antigen enters our body, the immune system is stimulated and produces antibodies in order to identify it. Then antibodies bind with antigens and neutralize them, reducing the risk of causing diseases. At the molecular level, an antibody has an antigen-binding site. An antigen binds with its specific antibody, like a lock and key. This antigen-antibody interaction triggers an immune response.
Figure 01: Antigens
Basically, antigens have two categories: self-antigen and non-self-antigen. Our immune system is able to tolerate self-antigens. However, it identifies non-self antigens as invaders and attacks them and destroys.
What is a Pathogen?
A pathogen is an infectious agent that causes a disease in plants and animals. Generally, pathogens are microorganisms such as virus, bacteria and fungi. We contact pathogens daily in our lives. It is important to remember that very few types of microorganisms are disease-causing. Therefore, not all microbes are harmful. The term pathogen refers specifically to the ones that cause diseases in the host. Our body also contains different types of microbes. Many are helpful bacteria. These useful microbes can be destroyed by chemotherapy or HIV infections.
Figure 02: Pathogen
Pathogen transmission occurs in many ways such as faecal-oral route, body fluid, through blood, breast milk, direct or indirect contact. In order to prevent transmission and diseases, there are different types of medications are available including vaccination, antibiotics, and fungicide, etc.
What are the Similarities Between Antigen and Pathogen?
- An antigen is a part of a pathogen that stimulates an immune response.
- Moreover, antigen and pathogen can trigger immune responses.
- Both of them are capable of causing diseases.
What is the Difference Between Antigen and Pathogen?
An antigen is a molecule that can stimulate immune responses in our body and can bind with a specific antibody while a pathogen is a harmful organism that causes disease in its host. Thus, this is the key difference between antigen and pathogen. Furthermore, a pathogen is an organism, but antigen is not an organism; it is a molecule located in the cell wall of bacteria or the coating of other microorganisms.
Summary – Antigen vs Pathogen
A pathogen is a microbe that makes us sick. In contrast, an antigen is a part of a pathogen that is capable of stimulating an immune response in our body. Thus, this is the key difference between antigen and pathogen. Furthermore, antigens are proteins, peptides, polysaccharides, lipids, etc. while pathogens can be viruses, bacteria, fungi, protozoans, etc.
Reference:
1. “Boundless Anatomy and Physiology.” Lumen, Available here.
Image Courtesy:
1. “Antibody” By Fvasconcellos 19:03, 6 May 2007 (UTC) – Color version of Image:Antibody.png, originally a Work of the United States Government (Public Domain) via Commons Wikimedia
2. “3758726” (CC0) via Pixabay