Vertebrates adaptive immune system, development

Higher vertebrates have developed an innate or natural immune response, as well as an adaptive response, to fight off microbial invasions. The innate immune response is triggered immediately after microbes attack the organism. The immune system targets common structures conserved in many micro-organisms to fend them off, and antimicrobial peptides -which are produced in large quantities at sites of infection and inflammation - are ancient weapons in these defense mechanisms [24]. 

---