Antigen vs Pathogen
In
 our daily life, we are exposed to different substances. Even though 
most of the people, most of the time, are healthy and have the ability 
to do their daily activities, sometimes, some of them fall sick or get 
illness, which is caused by pathogens.
Pathogens
 are any foreign organisms that cause diseases in host plants and 
animals; e.g. virus and bacteria. Antigen is a molecule located in the 
cell wall of bacteria or the coating of organisms. Antigen causes our 
immune system to produce the antibody against it and protect our body 
from harmful foreign organisms.
What is Antigen?
Originally
 the term Antigen came from Antibody generator. It may be any substance,
 which comes from the environment or forms within the body. Generally, 
antigens are protein and polysaccharide (capsule, coats, cell wall, and 
flagella) located in the cell walls of bacteria or in the coating of 
other organisms. It causes our immune system to produce the antibody 
against it. Antibody is used by the immune system to identify and 
neutralize the foreign particles like bacteria and viruses. Basically, 
antigens are categorized as self-antigen and non-self-antigen. 
Self-antigens are tolerated by the immune system while the 
non-self-antigens are identified as invaders and can be attacked by the 
immune system. Non self-antigens include egg white, pollen from the 
organs, and transplanted tissues.
At 
the molecular level, an antibody has the antigen binding site, in which,
 the antigen has the ability to bind. These triggers the response of 
different antibodies based on its match like a lock and key. An 
Immunogenic is an example for a specific type of antigen which is able 
to induce the immune response. The two types of antigens are exogenous 
and endogenous. Exogenous antigens enter the body from outside. E.g. by 
ingestion or inhalation. These are taken into the antigen present cells 
by endocytosis and then exocytosis process it into fragments. Endogenous
 forms within the normal cells by cell metabolism or viral intracellular
 bacterial infection.
What is Pathogen?
Pathogens are easily called as 
infectious agents. We contact pathogens in our daily life. These are 
microorganisms that cause diseases in host plants and animals; e.g. 
virus, bacteria, and fungi. Not all microbes are harmful; pathogens 
refer specifically to the ones that can cause disease in the host. The 
human body also contains helpful bacteria, which is called good 
bacteria. It may be destroyed by chemotherapy or HIV.
Pathogen transmission occurs in many 
ways such as fecal-oral route, body fluid, through blood, breast milk, 
direct or indirect contact.
Nowadays, there are many medical 
advances available against infection by pathogens like use of 
vaccination, antibiotics, and fungicide. Mostly Pathogens are negative 
but not all. Pathogens serve as natural or biological control, to 
suppress the arthropod pest populations.
The types of pathogens are viral, 
bacterial, fungal, other parasites, and prionic; e.g. Mycobacterium 
tuberculosi (a causative agent for most tuberculosis) and Fungs (affect 
athlete’s feet).
 
What is the difference between Antigen and Pathogen?
• 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 microorganism.
• Pathogen is a harmful organism that causes disease in its host.
• Antigen triggers the response of difference kind of antibodies based on its match like a lock and key hypothesis.
• Pathogen refers to any foreign 
organism, which is not part of the body, and presents inside the body, 
mainly in the blood stream, but antigen is a part of the body.
• Pathogens serve as biological controller but antigen doesn’t.
 
 



