The Evolutionary Origins of the Adaptive Immune System of Jawed Vertebrates

摘要: This chapter focuses on how the essential components of adaptive immune system-Ab, TcR, and MHC molecules-arose began to interact. The major histocompatibility complex (MHC) molecules are loaded with their antigens by sophisticated pathways composed various kinds molecules, some which encoded genes located in MHC. In all jawed vertebrates examined thus far, elements system present. Despite years functional experiments invertebrates pointing recognition allo- xenoantigens, none genetic were found first complete genomic sequences invertebrates: an insect (the fruit fly Drosophila melanogaster) a nematode worm (Caenorhabditis elegans). Therefore, notion that lack was strengthened, question became managed survive without is vertebrates. A key concept has relevance no matter what defense might be pathogens overcome hosts may face bleak evolutionary future, so, general, virulence constrained guided particular defenses host(s) evolve. Although there little scope observe evolution through fossils, it seems likely also evolved steps, separated between those organisms still living.