Explore the Difference Between Antigen and Pathogen

The difference between antigen and pathogen is easy to understand:

  • Antigen is the protein that is found on the surface of a pathogen
  • Pathogens are harmful microorganisms that can cause diseases.

As you can see, the two terms are related to one-another. In this article, we shall explore more similarities and the differences between the two in detail:

Difference Between Antigen and Pathogen



Antigen is a molecule

Pathogen is an infectious agent

Antigens are usually lipids, peptides or polysaccharides

Viruses, fungi, bacteria and other disease-causing microorganisms

Sources of antigen can include biological and non-biological origins.

Pathogens generally have biological origins – such as bacteria and fungi. It also includes non-living entities such as virus and prions


As stated above, antigens are molecules which are present on the surface of a pathogen. Their primary role is to elicit the response of the immune system. This in turn stimulates the production of antibodies, which are Y-shaped proteins that help fight off the infection. Antigens are usually present on the microorganisms, however, other substances such as chemicals, pollens or even autoimmune diseases can form antigens in the body.


Pathogens are essentially microorganisms that have the potential to cause diseases. Most pathogens have a biological origin – such as bacteria, protozoans and fungi. Non-living entities such as viruses and prions are also considered as pathogens as these cause diseases in their hosts. Each pathogen has a unique antigen that binds to special receptors in the host’s body. This antigen is regarded as a threat by the immune system and it starts producing antibodies in response.

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Frequently Asked Questions on Antigen and Pathogen

What is the difference between antigen and pathogen?

Antigen is the protein that is found on the surface of a pathogen. Pathogens are harmful microorganisms that can cause diseases in their host.

Explore more about antigens, pathogens or other related topics by registering with BYJU’S Biology.

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