What is 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	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

Antigen

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.

Pathogen

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.

Read More:

Frequently Asked Questions on Antigen and Pathogen