Pathogens that live outside the cells.
Sustancia que al introducirse en el organismo induce en este una respuesta inmunitaria, provocando la formación de anticuerpos.
These are part of the second barrier
We are born with this type of inmunologycal defense.
This are pathogens that need to live inside a cell.
They are the first barrier
These are part of the Third barrier
We acquired this type of inmunologycal defense along aour lives.
Any external biological agent that can harm the host
